Ecologist's Notebook

Raised garden beds in Colorado. Photo by D. Sillman

(To listen to an audio version of this blog, please click on the following link …Robin Nestlings in the Yard

A few weeks ago Deborah, Ari and I were out in our backyard. I was watering the garden and Deborah and Ari were playing in the sandbox. While I was watering, two robins kept fussing at me from the top of the fence and the edge of the gutter on my bordering neighbor’s garage. Their behavior was quite strange.

Earlier, I had seen robins (possibly these two who were harassing me) diving into the very cherry tomato patch that I was currently watering. I had wondered if they were plucking off the little, ripening tomatoes? I had never seen robins eating tomatoes, but thought that it was something worth watching more closely. Could the robins have been defending a newly discovered food source?

Robin fledge. Photo by D. Rosser. Flickr

I finished up my watering by emptying the hose on the Rocky Mountain juniper bush growing in the flower bed next to the edge of the patio. That’s when I found out why the robins were being so loud and aggressive. The spray from the hose startled two robin nestlings out from under the juniper. They ran from the water spray over into the shelter of a nearby sumac and rustled around in the weed cover peeping their heads off. The adult robins were perched nearby, giving me quite a severe talking to.

I called Ari and Deborah over to the sumac and we watched the baby robins run back and forth in the cover of the bushes and weeds. At one point one of the adult robins dropped down into the flower bed and stuffed some food (Worms? Caterpillars? I was too far away to see.) into the nestling’s mouth. The nestling then settled down to swallow and digest and was quite quiet for several minutes.

Photo by D. Sillman

Every one of us has either found a baby bird hopping around on the ground making loud, “I-don’t-know-how-to-fly” noises, or we have received such a bird from some well-meaning relative, friend, or acquaintance. This is a situation that pits our emotional selves (“the poor little bird!”) against our scientific selves (“he’s fine, or if he isn’t, that’s fine, too!”).

The best thing for a bird lover to do when they see baby birds on the ground is to leave them alone! The parents know what they are doing and are working hard to get their progeny through their last big, developmental hurdle!

And, the experts agree with this “hands-off” approach. The United States Fish and Wildlife Service (US-FWS) has an excellent web page about what to do when you find a baby bird. They categorically state that the best thing you can do for the bird is to leave it alone. Its chances for survival are much higher if you don’t interfere with whatever is going on (and this is very important: you don’t know what’s going on when you see this little bird trundling around on the ground! Maybe there are reasons (and benefits) for his being there, maybe it’s just some random mishap. Knowing that you don’t know what is going on may be the first step toward some type of ecological, Socratic wisdom!).

Baby robins, Free Image, Pixabay

Another expert on baby birds is “Sialis.” Sialis is an organization named after the genus (and also the species) of the eastern bluebird (Sialis sialis). Sialis’ website has a wonderful set of pages loaded with a great deal of practical information about bluebirds and many other small types of birds. I recommend you go there and browse around its pages. Anyway, Sialis has the same basic philosophy as the US-FWS: if you find a bird, leave it alone! Although, the site does then goes into a detailed set of possible contingencies, exceptions and scenarios.

Over the years of our Harrison Hills Park bluebird study, we regularly came across pre-fledgling bluebird nestlings running around in the vegetation under their nesting boxes. None of us ever tried to catch the baby birds and put them back in their boxes! The parents knew where they were and were feeding and caring for them as intently as they had been for the weeks the little birds had been living and growing in their nests!

First and foremost you should know that it is illegal to possess a wild bird or any other wild animal. The laws that govern this are extremely logical and are designed to let wild animals live as freely as possible away from human interference. Also, an untrained person trying to raise, say, a wild baby bird almost certainly guarantees that that baby bird is going to die.

Photo by R. Bushby, Wikimedia Commons

So, what if there are dogs and cats around in the yard where the baby bird is chirping about? Best thing to do is to put the dogs and cats somewhere else and let the bird follow its destiny. If that’s not possible, gently remove the bird from the ground level (picking it up in a pillow case or t-shirt is best so that you don’t snag its toenails or feathers) and place it up somewhere out of reach of muzzles and claws (in a bush or up on a tree branch, or back in its nest if the nest is visible and accessible). Your scent will not affect the treatment of the baby bird by its parents (that’s an old Mother’s Tale designed to keep children from handling baby birds). You might even make an artificial nest or protective enclosure for the bird to help to keep it safe (check out the Sialis description of these kinds of nests and enclosures!). If none of these options are possible, then you might have a reason to take the bird out of its yard. This removal should only be done with great caution and reluctance, though. The baby bird’s parents are probably lurking nearby with beaks full of mushed crickets and caterpillars. The web sites say you watch the bird for at least two hours before presuming that it is abandoned.

Why would the baby bird be on the ground in the first place? Maybe the nest got too crowded, and the bird and possibly several or all of its clutch-mates had to abandon their cozy egg-home. Getting out of the nest, in fact, may help to reduce predation on the nestlings! Nest predators (like possums, raccoons, hawks, jays, crows, and maybe even snakes) eventually will cue in on the constant in’s and out’s of the parental birds carrying their phenomenal load of nestling food into the nest. Getting out of the nest as early as possible might just be a very solid survival strategy! Also, many bird species have several days of almost-flying fledging in which the nestlings exercise their growing wings to get to the point of being able to fly. These grounded fledges make up a significant proportion of the “saved” baby birds, but they really don’t need to be saved: their moms and dads are close by and are both watching and feeding them continuously.

Photo by D. Sillman

Now, that baby bird might be on the ground by accident and for no good reason or for any benefit to themselves is also a possibility. Maybe their nest fell apart, maybe there was a wind storm, maybe the branch the nest was placed was rotten. Equally possible, though, is that the parental birds screwed up. They didn’t display the optimal behaviors in nest site selection or building or in their nestling rearing practices. If so, Natural Selection might be best served if those parental genes were not continued in the population. Richard Dawkins might have been thinking about baby birds out of their nests when he said: Nature is not cruel or kind, it is just indifferent to suffering.

The next day I saw one of the baby robins up in the branches of a small, blue spruce tree growing just inside my north-side fence. One the parent robins was flying in and out of the spruce, probably delivering food. I am sure that the other baby robin was still out in the backyard, too.

When Ari went home the evening after we first found the baby robins, he talked and talked about the baby birds and their parents. He has since made up a new imagination game in which he is a baby pterodactyl and we are his parents (and grandparents) bringing him food. Good fusion of modern and paleo-ecology!

Photo by D. Sillman

(Click on the following link to listen to an audio version of this blog … Our Yard part 4

When we moved into our Greeley house in late July, 2020 there were several tiny flowering plants primarily growing out from the thin spaces in between the sidewalk and driveway concrete pieces on the southwest corner of the front yard. The flowers were small (about a half an inch in diameter) but stunningly beautiful. Their delicate beauty seemed to contradict their apparent “weed-like” locations and growth habits!

The flowers each had five petals (two purple, two white and one yellow) that sat atop six-inch-tall stalks that were loaded with dark green, lanceolate leaves. We had seen these flowers before in our front yard back in Pennsylvania. In fact, we had watched them, over the years, steadily spread across our yard and on out into the neighboring  field. They were “Johnny Jump Ups,” or “wild pansies” (Scientific name: Viola tricolor).

Wild pansies are native to Europe but have been in North America ever since European colonization. Some, undoubtedly, were imported purposefully to plant in flower gardens for their beauty or in herb gardens for their use in a variety of folk-medicine cures (they were traditionally used to treat a wide range of maladies including eczema, bronchitis and asthma). Thomas Jefferson grew wild pansies in his garden at Monticello and wrote about them in his notebooks. Today, most major seed companies sell wild pansy seeds, and many garden websites extoll their beauty and vigor. However, many states have listed V. tricolor as an invasive species whose rapid rate of reproduction and extremely robust rate of proliferation and spread can negatively impact a long list of native species.

Photo by D.Sillman

In short, these wild pansies are exotic, invasive weeds, but to their credit they are beautiful! Their presence gave our sunbaked, flower-starved yard of summer 2020 a very nice splash of color! We decided, in spite of their aggressive nature, to let them grow!

Wild pansies bloom from late spring to the end of summer with a significant burst of mass flowering in the month of June. Their name “Johnny Jump Up” refers to their remarkable ability to send their seeds across broad areas of lawn or field where they germinate and “jump up” in the next growing season. This “jumping” potential is due to two factors: 1. The oval seed pods of the plants, as they dry, become tense, tightly coiled, spring-like structures. When these pods are excessively heated (as on a very hot,

Johnny Jump Up seed pods. Photo by D. Sillman

sunny day) or if they are mechanically disturbed (as by a passing animal or even a strong wind gust or a striking raindrop), they burst open and fling their seeds out into the air. Some viola species, using these “ballistic dispersal” mechanisms, can send their seeds up to 16 feet away from the parent plant! And, 2. Once the seeds hit the ground, they attract the attention of ants! The ants pick up the seeds and carry them off to their underground nests. Although the ants undoubtedly consume some of the seeds, more than a few survive and, after being transported significant distances from their parental sources, germinate and then “jump up” the next spring!

Here in Greeley, we have watched our wild pansies march across the front yard. At first (summer 2020) they were confined to the southwest edge of our property, but by 2021 they had reached halfway across the mulched section of the yard. By this spring (2022) they had reached all the way to the sidewalk at the edge of the mulched areas. They lined the edges of the gravel walkways and rock “dry creek beds” and grew straight up out of the shredded cedar mulch. They were beautiful but were beginning to make us a bit uneasy!

We have decided that they have spread far enough and have started to collect the drying plants. Hopefully, we’ll be able to gather them with their as yet unexploded seed pods (although this seems unlikely based on our most recent examination of the plants). We would like to keep them from entering the north part of the front yard where the buffalo grass is growing. We’ll see if we can control the spread of this feral flower or if we have to add them to our “bad weed list” next spring!

Photo by D. Sillman

Our second, “unintended” yard component came in from nearby roadsides and field edges: wild, common sunflowers (Helianthus annuus).  In summer 2021, we had four, robust patches of these volunteer sunflowers out in our front yard. They self-seeded (probably via bird transport in the previous summer or fall). Seeds from these 2021 sunflowers, then germinated all across the yard in spring 2022 and we then had hundreds of wild sunflowers growing all across the front of our house.

The rate of growth of these plants was astonishing! I have photographs of the front yard in mid-June 2022 in which there are no sunflowers in sight and then, three weeks later, the same view was dominated by a dense, three-foot tall, sunflower jungle! We were forced to thin the sunflower plants very aggressively in order to have room for our other front yard plants to grow!

Photo by D. Sillman

When these sunflowers were young and growing so rapidly, we watched them exhibit the property of “heliotropism.” At dawn, the entire yard of sunflowers were positioned so that their developing flower heads faced the east and the rising sun. They then, through the day, slowly turned their flower heads to follow the sun across the sky until at sunset, they were all facing to the west and the setting sun. Only the young sunflowers exhibited this behavior, though. The older, mature sunflowers positioned their flower heads toward the east and kept them there.

One explanation of this interesting behavior is based on the previously mentioned rapid growth rate of the sunflower stems. Apparently, during the day, the cells and tissues on the east side of the stem grow more rapidly than those on the west side, thus turning the sunflower head to the west. At night, the cells and tissues on the west side of the side of the stem grow more rapidly, thus turning the sunflower head back to face the east. By the time the sunflower is fully grown, though, these stem cells and tissues have stopped growing and the heliotropic behavior ceases to occur!

Photo by D. Sillman

The pollinators love the sunflowers! There have been clouds of buzzing insects around the flower heads from the end of June well into August! The sunflowers are an important source of nectar and pollen for these insects and help to sustain these vital organisms through the summer season.  Deborah did a visual census of these sunflower pollinators and observed honeybees, bumblebees, several species of solitary ground bees,  vespid wasps (yellowjackets, paper wasps and pollen wasps), several species of mud daubers (including the black and yellow mud dauber (who were there hunting spiders to provision their nests!)), several kinds of beetles and homopterans, damselflies and more! Talk about a keystone species!!

Common sunflowers are one of five native, sunflower species found here in Colorado. The other four native species include the Maximillian sunflower (H. maximilanii) which grows all over the Americas in dense clumps of ten foot-tall stalks (we planted Maximillian sunflowers in one of our “intended” garden planting rings, and I wrote about them last week!), the Nuttalls sunflower (H. nuttalii) which grows primarily in the damper regions of the nearby foothills of the Rocky Mountains, prairie sunflowers (H. petiolaris) which make relatively low, branching sunflower-bushes especially along roadsides that cut through the Colorado plains, and bush sunflowers (H. pumilus) which primary grow on dry hillsides.

Public Domain

The common sunflowers (H. annuus) are the wild stock from which Native Americans some 3000 years ago derived the larger seeded common sunflower which they then grew extensively across North America as a food plant. Some scientists think that these cultivated sunflowers were actually developed for human food even before corn! These native American sunflower varieties were exported to Europe in the 1500’s (in that great, post-Columbian shift of plant species back and forth across the Atlantic Ocean!) and then were further developed into the very large flower/very large seed varieties that are currently grown around the world for human consumption, oil, and livestock and wild bird feed.

Last year, starting in late September, birds (house finches, chickadees and house sparrows) swarmed the flower heads and gobbled down the tiny seeds. Several fox squirrels also climbed up the two and a half inch thick sunflower stems and pulled whole flowers off of the plant to eat the seeds. Then one day in early October, a flock of goldfinches (a bird I had not seen all summer) descended on one of the sunflower patches. The adult finches pulled seeds out of the dry flower heads while a large number of their recent fledglings peeped and fluttered at them demanding to be fed. One reference that I consulted stated that the late summer reproduction timing of goldfinches is primarily driven by the late summer abundance of wild sunflower seeds!

This year, the goldfinches showed up in our sunflower jungle in July! They have been feasting on the maturing seeds along with flocks of house finches for the past month!

In 2021, the plants quickly lost their summer luster and turned brown with the coming fall. They were not very attractive out in the front yard but were feeding so many animals in the yard that we decided to leave them in place until they have been stripped bare of seeds. A prodigious number of seeds fell off of these 2021 plants and caused the sunflower explosion of 2022! Left alone, it seems that the whole world would soon be completely covered with sunflowers! I hope that we have room for a few other, “non-sunflower” plants next summer!

Photo by D. Sillman

(Click on the following link to listen to an audio version of this blog … My yard part 3

Continuing with the ”intended components” of our yard. These are the plants we purchased from the High Plains Environmental Center (Loveland, Colorado) and ones that we grew from seed that we obtained through the Audubon Society of the Rocky’s “Habitat Hero” program. All of these plants are growing in our “planting rings” and all of them are drought-resistant, Colorado-native species that are important in the dryland ecosystems around us!

Butterfly weed and black-eyed Susans. Photo by D. Sillman

Butterfly Weed (Asclepias tuberosa): Butterfly weed is type of milkweed. Its bright orange flowers produce large amounts of nectar which in turn attract large numbers of butterflies. The primary pollinators of this plant, though, are bees and wasps which are also seen in great swarms around the flowers. Butterfly weed grows in prairies, open woodlands, rocky canyons and hillsides. Like all of the plants listed here, it is extremely drought tolerant and requires little care or watering to grow and thrive.

Photo by E. Hunt, Wikimedia Commons

Blue Wild Indigo (Baptisia australis): Blue wild indigo, according to most references, is found in prairies, woodlands and stream sides all across the eastern portion of North America up to western sections of Oklahoma, Kansas and Nebraska. The High Plains Environmental Center in Loveland, Colorado (where we purchased our blue wild indigo plants), though, includes it in its local “native plants” inventory, so its western boundary must have stretched out into Northern Colorado in recent years.  It is a perennial that reproduces by seed and via sprouting from its extensive rhizome. Seed production in the wild is quite compromised because of the impact of a seed-eating, parasitic weevil. It is a bushy, robust perennial that makes abundant, blue-purple, pea-like flowers on vertical spikes. The flowers are a rich nectar source for a wide array of bumblebees, butterflies, and many other pollinators. As its flowers indicate, it is a member of the pea family and, so, is capable of symbiotic nitrogen fixation via its root nodular bacteria. Its dense root system off of its extensive underground rhizome helps to make it extremely drought tolerant. Many caterpillars feed on the leaves and stems of blue wild indigo including the clouded sulphur, orange sulphur, eastern tailed-blue, and the wild indigo duskywing.

Photo by D. Sillman

Blue Flax (Linum lewisii): Blue flax is also called “prairie flax” and it is a common component of prairies and steppes all across the western two-thirds of North America (from subarctic Canada down into northern Mexico). It is an extremely drought resistant, shrub-like perennial whose two foot tall stems are covered with needle-shaped leaves and abundant one inch, pale, five petaled, blue flowers. The plant drops its mature flowers each day by early afternoon and then unfolds a new set of flowers at sunrise the next day. Native bees are especially attracted to these flowers for their nectar and pollen along with a wide variety of other pollinators (especially flies). The entire plant can be eaten by grazing/browsing animals (especially deer, proghorns and elk) in spite of the presence of compounds that

Close up of blue flax. Photo by D. Sillman

can be converted into cyanides by rumen and gut microorganisms.  Seeds produced by blue flax are eaten, especially in the winter, by a variety of birds (including sage grouse). Ground squirrels and chipmunks, however, seem to avoid eating flax seeds while deer mice readily consume them (it makes up to 16% of their ingested food).

Black-Eyed Susans (Rudbeckia hirta):  Black-eyed Susans are native to the eastern and central portions of North America but have been extensively naturalized all across the continent. They are found in all of the lower 48 states and in 10 provinces of Canada. Growing primarily in meadows and prairies. This bi-annual plant (it flowers in its second year of growth) forms its distinctive yellow-petaled/black to brown centered flowers on top of stems that grow one to three feet high. The flowers last a very long time and are an important nectar source for butterflies and other pollinators. A number of lepidopteran caterpillars develop on the foliage of black-eyed Susans (including the bordered patch, the gorgone checkerspot and the silvery checkerspot). Seeds in the old flowerheads are an important fall food source for birds.

Prickly pear and yucca. Photo by D. Sillman

Plains Prickly Pear Cactus (Opuntia polycanthus): I felt that it was essential to have a patch of prickly pear cactuses growing in our dry-steppe front yard! They are one of the truly emblematic plants of the dry ecosystems of the West! Plains prickly pear is the most widely distributed cactus in North America. It is found in the deserts of West Texas all the way over to the Pacific Ocean and northward into the central and western Canadian provinces of Alberta, British Columbia and Saskatchewan. One of the reasons that plains prickly pear is so widespread is its ability to tolerate freezing temperatures and prolonged winters. In the winter the aboveground paddles dehydrate in order to protect the plant’s tissues from freeze damage. They then lay flattened, discolored and deflated on the ground (see Signs of Winter 9, February 17, 2022 for a discussion on the overwintering physiology of prickly pear cactuses).

Prickly pear in flower, June 2022. Photo by D. Sillman

Prickly pear cactuses grow in clumps of spiny, six-inch-long pads and may form a paddle mass that stands up to two feet tall. The pads are actually flattened, expanded stems that are designed to store moisture and the covering cactus spines arise from structures that in other plants make leaves. A pad may last for up to ten years and a stem may make a new pad every year, so there is a significant rate of growth in these prickly pear patches. New pads are able to grow roots down into the soil and thus stabilize the expanding cactus patch. Flowers form at the top of the paddles in early summer and produce abundant nectar for a variety of pollinating insects. The actual pollination of the prickly pear flowers, though, is mostly carried out by beetles. The fruit formed from these pollinated flowers are eaten by many animals. Coyotes (which, unfortunately, we don’t have in our front yard ecosystem!) are said to be extremely fond of these sweet cactus fruits.

Photo by D. Sillman

Yucca (Yucca species):There are 49 species (and 24 subspecies) within the genus Yucca. One of the great, and historically evocative common names that actually appended to several of these species is “Spanish bayonet.” Yuccas are shrub to tree-sized, evergreen perennials that have a rosette (“circle”) of tough, sword-shaped leaves growing up from its base and tall, branching white flowers masses that then project up out of the rosette mass. They are found throughout Mexico and up into the southwestern and dry central states of the United States all the way to southern Alberta (Canada). They also extend along the coastal woodlands and beaches of the Gulf Coast states up around Florida to the dry, coastal habitats of the southern Atlantic states.

The pollination of yucca flowers is carried out by specialized lepidopterans called “yucca moths.” (a species of either a  Tegeticula or Parategeticula moth). The female yucca moth when it transfers pollen to the yucca flower also lays one of its eggs in the flower. The developing larvae then eats most (but not all!) of the yucca seeds leaving sufficient seeds for the perpetuation of the yucca plant. Yucca plants also serve as a food and development site for several other types of lepidopteran species.

In the dry prairies and steppes of Colorado, yucca is often one of the only green plants see on a winter hike! Its evergreen nature really stands out against the overwhelming browns and grays of the High Plains winter!

(Next week: the unintended plants of our yard!)

our house in Greeley when we moved in (July 2020)

(Click on the following link to listen to an audio version of this blog … My yard part 2

Deborah and I wanted the yard of our new house to support three things: 1. a place for our grandson, Ari, to play, 2. an area of native grasses that would resemble a mini-shortgrass prairie and, 3. a place where we could grow as many species of native, dry-steppe plants as we could. Our guiding themes in all of this were minimizing water usage and using native plants that would support pollinators and as many other insects (and their larvae) as possible!

As I wrote last week, we dedicated the back yard to be the Ari-play-area and covered it with playground mulch, a climbing dome and a swing set. We had a landscape contractor remove the front yard turf and left about a third of it of it (about 1300 square feet) to be converted into prairie. The other two-thirds (about 3000 square feet) we bordered with rock “dry creek beds,” crisscrossed with a compacted gravel pathway and then constructed a set of brick-lined planting circles from one end to the other. That fall (2020) we heavily mulched (finely shredded cedar (“gorilla”) mulch) around the planting circles.

Front yard planting ring. Photo by D. Sillman

In spring 2021 we tilled up the very compacted soil within the planting rings and enriched it with compost. We then planted an array of native, flowering perennials, yuccas and cactuses in the rings. These plants are what I would like to call the “intended components” of our yard. There were also “unintended components” in the form of wild and feral plants that began to grow in the protected spaces of the yard (but I am going to talk about those the week after next!).

The ”intended components” of our yard consisted of plants we purchased from the High Plains Environmental Center (Loveland, Colorado) and ones that we grew from seed that we obtained through the Audubon Society of the Rocky’s “Habitat Hero” program. We put the plants and/or their seeds out in the planting rings of our front yard in the spring of 2021 and replanted (when necessary) in the spring of 2022. Many of the plants we selected were listed in D. Hazlett’s comprehensive description of the 521 plants growing in the nearby Pawnee National Grassland (USDA publication: “Vascular Plants of the Pawnee National Grasslands”), and all were native to Colorado and all had characteristics that were favorable to pollinators and other types of insects (as described by D. Tallamy in his “suburbitat” publications).

Tallamy has looked  deeply into the human-created habitats in our cities and suburbs and has some important insights about the quality of these ecosystems. It is not enough, he states, to just make green, leafy spaces around our homes. Those spaces have to be conducive to the growth and survival of native insects in order to be considered a fully functional component of the biosphere. We need to think about trees and about all of the plants growing next to and under and on top of those trees in order to really develop functioning ecosystems!

Photo by D. Sillman

Tallamy proposes that we “re-wild” the America landscape by shrinking our lawns (a very unproductive and lifeless expanse of alien plant species (the “Kill Your Lawn” program recently featured in the New York Times (June 15, 2022) is even more adamant about the need to get rid of that patch of alien grasses that sits in front of your house!). He also proposes that we remove those exotic plant species that have been favored by ornamental gardening and landscaping practices since so many of these species are not palatable to our local vertebrate or invertebrate consumers. We need to create no-mow zones (to stop from grinding up billions and billions of grass-dwelling organisms), reduce outdoor lighting (which disrupts local invertebrate and vertebrate activity patterns and also long distance migration pathways), plant keystone species (those plants that are shown to be , region by region, critical to the life cycles of our pollinating and decomposing insects), welcome pollinators, and avoid chemical herbicides and pesticides. The resulting, complex suburban and urban vegetative habitats would be full of munching caterpillars, hunting spiders and a glorious diversity of beetles and other insects than would, in turn, support and sustain a myriad of birds and other vertebrates that feed on them.

So what all did we plant in our yard?

Photo by D. Sillman

Rocky Mountain Blazing Star (Liatris ligulistylis): a spectacular and extremely long-lived, flowering perennial with tall, spiky, purple flowers and dense, grass-like leaves. The flowers attract a large number of pollinators including many lepidopterans. It has a very deep root system which makes it extremely drought-resistant. Blazing star leaves are eaten by the caterpillars of a number of flower moth species (like Schinia gloriosa and S. sanquinea). The plants overwinter as underground tubers called “corms.”

Public Domain

Coneflowers (Echinacea purpurea and E. angustifolia): purple cornflowers (E. purpurea) grow throughout the eastern and central regions of North America. The can be found in moist and dry prairies and woodlands and are important nectar sources for a wide range of bees, butterflies, wasps, beetles and flies. Most of the pollination of these flowers is carried out by bees and butterflies. Coneflowers also produce abundant “thistle-like” seeds in the late summer and early fall that are avidly consumed by a wide range of birds (including goldfinches, cardinals and blue jays). Purple cornflowers differ from other coneflower species in that they do not have deep taproots. The basal stem of the purple cornflower (its “caudex”) is densely covered with abundant, but shallow fibrous roots. Although this plant is very drought resistant, its lack of a tap root may limit its ability to survive long periods of extremely dry conditions. The very similar narrow leaved coneflower (E. angustifolia), however, does have a very long, delicate taproot that enables it to reach down into the subsoil for its moisture requirements. The narrow leaved coneflower is found primarily in western and central dry prairies and is highly valued for its use in traditional, folk medicine (to treat snake bites, sore throats, toothaches and headaches)

Photo by D. Sillman

Maximilian sunflower (Helianthus maximilianii): Maximilian sunflowers are one of the five sunflower species that are native to Colorado. It is found extensively across the Great Plains and also across most of North America. Maximilian sunflowers grow from a thick (and edible!) underground rhizome and form a dense mass of thin, tall (1 ½ to 10 feet) long-leafed stems with bright yellow flowers (2 to 3 ½ inches across) at their tips. The flowers attract a wide range of pollinators and nectar feeders (including many wild and domesticated bees, butterflies and beetles). The stems and leaves support numerous caterpillars of moths and butterflies, and the seeds produced by the flowers are consumed by a wide range of birds and mammals. At all stages of its life, this plant supports other living organisms! It is, clearly, a keystone species in any dryland ecosystem!

Photo by D. Sillman

Blanket Flower (Gaillardia aristate): Common blanket flower is said to have gotten its name from the similarity of its flower colorations to the colors of traditional blankets made by Native Americans and also from its tendency to grow into a dense “blanket-covering” of flowers across an area. It is a very short-lived perennial (2 or 3 years) but extremely drought-resistant and especially found in dry prairie habitats east of the Rocky Mountains and on up into the mountains themselves. It is a frequent food plant for a variety of lepidopteran larvae. Many types of bees (both wild and domesticated) and butterflies come to blanket flowers for nectar.  Species of blanket flower are found all across North and South America.

Photo by T. Tuason, Wikimedia Commons

Western White Clematis (Clematis ligusticifolia): Western clematis is also called “virgin’s bower” or “pepper vine.” It’s natural range covers most of western North America, and it grows in a wide range of habitats (from streamside riparian forests, to ponderosa pine stands, to dry sagebrush deserts). It is very drought tolerant and generates a dense covering of delicate, white, extremely fragrant flowers that attract large numbers of insects (including many types of bees and butterflies) and also hummingbirds. Birds frequently make their nests in the protected spaces enclosed by the clematis vines. The flowers after pollination form plume-like seed heads which further contribute to the concealing and protective nature of the vines. The common name “pepper vine” comes from a Native American practice to chew clematis stems and leaves for their refreshing, pepper-like taste. Native Americans also used these leaves to revive tired horses! Great caution should be taken when eating these leaves, though, because clematis contains significant levels of very poisonous chemicals.

(Continued next week!)

our house in Greeley when we moved in (July 2020)

(To listen to an audio version of this blog, please click on the following link … My yard part 1 )

When we moved to Greeley in July 2020, the yard of our new house looked like most of the yards in our neighborhood. With the exception of some small, ornamental spruce trees that were planted in the middle of four stone rings, and a narrow, surrounding border of cobble-sized stones, the broad, front yard was a dense, thick mat of bluegrass and fescue, and the backyard, with a slightly wider, stone border, was the same. There was an automatic, underground sprinkler system located in the garage controlled by a bewilderingly complicated control box  that somehow my daughter figured out how to use (those millennials, is there anything they can’t do?). She programmed the system to soak the 6,000 square feet or so of lawn with water several times a week.

When we moved in, I was faced with a densely packed lawn that was six or seven inches high. My little electric mower struggled to get though the grass, and I ended up have to cut it back with my string trimmer. LOTS of grass!!! Amazing production!!

Photo by D. Sillman

According to the extension office at Colorado State University most lawns in Colorado are a mix of Kentucky bluegrass, tall fescue and perennial rye. The “Kentucky bluegrass” is not actually from Kentucky, by the way. It is an introduced plant native to Europe, Asia, and northern Africa! It is incredibly common in lawns all across the United States and Canada but is classified as an invasive and destructive species in most natural grasslands. Tall fescue is also an introduced grass species that thrives in marginal environments primarily because of a endo-symbiotic fungus. That fungal symbiont, however, has toxic effects on horses or cattle that might graze on it. Perennial rye grass is also an exotic, introduced plant species that is native to Europe, Asia and northern Africa.

So the lawns all around us are green swaths of exotic and, potentially, invasive and toxic plant species! Add to these disturbing features that fact that a bluegrass lawn, according to the Colorado State Extension service, requires 2.5 inches of water a week in order to survive! Over the five, “Colorado summer” months (May through September) that would mean that a bluegrass lawn will consume 55 inches of water! That represents almost 400% of the average annual rainfall here in northern Colorado!

I could not be a part of this immoral use of water, so I turned my sprinkler system off and, over the next few weeks, watched the thick, ecologically sterile grass ecosystem of my yard slowly turn brown and crispy. My neighbors commented that my sprinkler system must be broken! The people who previously lived in this house, they said, had had such a lush lawn! They had also had summer, monthly water bills that ranged between $300 and $400 dollars!

Once the grass was dead I contracted with a local landscaping company to come out and remove the sod. For a very reasonable price, they came in with their scraping machines and in a few hours had peeled way the front yard sod layer and piled it into several of their trucks (to take to a composting site). They left behind a smooth expanse of grassless, sandy soil.  We wanted our yard to support three things: 1. (in the back yard) a place for our grandson, Ari, to play, 2. (in the front yard) an area of native grasses that would resemble a mini-shortgrass prairie, and 3. (also in the front yard) a place where we could have planting areas to grow as many of the native, dry steppe plants as we could. Our guiding themes in all of this were limiting the amount of water requird to sustain the systems and using only native plants which would, inturn, support pollinators and as many other insects (and their larvae) as possible!

Photo by D. Sillman

The back yard was easy. We shut off the sprinklers and let the grass die. The next summer we raked up the dead grass and covered the area with landscape cloth. We then spread five cubic yards of playground mulch (a very soft mix of shredded wood chips) and put up the swing set, slide and climbing dome and were done! Nothing but fun!!

Early growth buffalo grass. Summer 2021. Photo by D. Sillman

The spring after we had had the sod removed from the front yard, we rototilled the prairie area and spread a good layer of compost over it. There are two dominant grasses that make up between 70 and 90% of the plants in a shortgrass prairie: buffalo grass (Boutelouia dadyloides) and blue grama (Boutelouia gracilis). So we seeded our area first with buffalo grass (in May) and then over-seeded it with a mix of buffalo grass and blue grama (in mid-June). The new seed required watering, so every morning and every evening we watered the area for 20 minutes. Our water bills stayed just under $100 a month during this period, so we were using considerably less water than the previous home owner to support our developing grassland. The May seeding germinated slowly but, eventually grew into a 30 or 40% surface cover of buffalo grass along with a 60 to 70% cover of some remarkably hearty and tenacious weeds!

Close-up of buffalo grass runners. Photo by D. Sillman

Before we could do the June over-seeding of our prairie-to-be, we had to remove those weeds. The list of species that were growing in this limited area is impressive as were the weight and volume of pulled weeds. We filled a wheelbarrow every morning (we could only work out in the yard until about 11 am because of the heat) and packed  large trashcans full of weeds every week for much of the summer!  Some of the most abundant weeds in the yard were field bindweed, Canada thistle, buffalo bur, lambs quarters, kochia, spurge (both spotted and prostrate), common purslane and storksbill.  You can read about these “good” and “bad” weeds in Signs of Summer 9 and signs of Summer 10,  August 5 and 12, 2021.

Buffalo grass over the winter (2021-2022). Photo by D. Sillman

In the fall (2021) we stopped watering the prairie and the grasses got dry and crispy and turned a tawny, golden brown. They stayed like that all through the winter. We anxiously waited for the spring rains to come to wake up plants and bring back the green.

Unfortunately, instead of the almost 10 inches of precipitation (snow and rain) that the U. S. Climate Data website predicts as the average for Greeley, Colorado from January to July, we only received 3 ½

Buffalo grass starting to green up, early June 2022

inches. The May/June short burst of rain started the greening of the buffalo grass, but then it began to slip back into its dry, dormant state.

What to do? I could start up the sprinklers and drive the prairie into a lush green state, or I could rely on the inherent resilience of these dryland grasses to remain alive and healthy in their dry, quiescence forms and wait for rain to come to re-awaken them,

I chose to wait.

My front yard prairie looks like the dry, rolling grasslands out on the nearby Pawnee Grasslands. You can feel the ecological anticipation and the built-up need for the arrival of precipitation! The summer monsoon, the long fall rains, the steady winter snows: anything! Very few weeds are growing in our prairie this year (the grasses are too dense and the weeds can’t grow without water). The grasses, though, can wait out dry spells of considerable lengths. They have evolved in our on-and-off, fluctuating climate and are able to abide. It would be so easy to flip on the sprinkler, though! Patience is a very hard thing to practice!

(Next week: the rest of the front yard!)

Spotted lanternfly. Photo by J. F. Orth, FLickr

(To listen to an audio version of this blog, please click on the following link ….. Pythons, mosquitoes and leeches

I have written about invasive species many times before. I have done blogs about invasive insects like gypsy moths, Asian tiger mosquitoes, brown-marmorated stink bugs,  spotted lanternflies and Asian lady beetles. I have done blogs about invasive birds like house sparrows and European starlings. I have also written extensively about exotic, invasive plants both back in Pennsylvania (where they have increasingly come to dominated our woodland trails, roadside ditches and old fields) and here in Colorado (where our “natural” grasslands now contain almost 30% invasive species and our riparian woodlands are increasingly overwhelmed by exotic species like Russian olive).

I even did a blog about the exotic, invasive species that was described in a New York Times article as “the most dangerous and destructive exotic, invasive species affecting our aquatic ecosystems today.” This deadly beast was, quite surprisingly, the common goldfish (Carassius auratus) ( see Signs of Fall 7, October 20, 2016). The impact of the rapidly growing and even more rapidly reproducing  goldfish on natural freshwater streams, pond and lakes, though, is devastating!

In the goldfish blog (entitled “The Anthropocene R Us” (one of my best titles ever!)) I listed some other more obviously damaging exotic, invasive species that were affecting aquatic and semi-aquatic  ecosystems all across North America. One of these species gets a lot of press coverage in part because of a widespread bias and fear that is shared by many humans (some say that it is a fear that s written into our primate DNA), and also because of its charismatic presence and almost supernaturally, monstrously, large size. This is species, of course, the Burmese python (Python bivittatus).

Photo by NPS, Public Domain

Burmese pythons were very popular pets in the last decade of the 20^th Century and the first decade of the 21^st. Between 1996 and 2006 over 90,000 Burmese pythons were imported into the United States as part of this pet trade. Breeding centers for Burmese pythons were also established primarily in warm, tropical to semi-tropical areas of the United States in order to satisfy the demand for these very large snakes (they can reach lengths of 23 feet and can weigh up to 200 pounds!).

One of these breeding centers, in Florida, was destroyed by Hurricane Andrew in 1992 and an unknown number of pythons escaped into the wilds of the Everglades and began to feed (they are stealthy, ambush predators that often hide in shallow water and strike and constrict their prey when they come to the water’s edge to drink) and breed (a Burmese python nest typically contains between 50 and 100 eggs).  Pretty soon there were A LOT of gigantic, Burmese pythons in the woods and wetlands of south Florida.

The impact of these invasive snakes on the biotic communities of the South Florida ecosystems has been severe. They have eaten large numbers of birds, mammals and other reptiles. They consume anything from small song birds to adult deer and alligators! A 2012 report on the wildlife of the southern regions of Everglades National Park indicated that since 1997 racoon populations have declined 99.3%, opossum populations have declined 98.9%, white-tailed deer populations have declined 94.6%, bobcats have declined 82.5%, and marsh rabbits, cottontails, and foxes have been completely wiped out.

Burmese python nest, Photo by NPS, Public Domain

Recently, though, a team of ecologists from the U. S. Geological Survey, the National Park Service and the University of Florida made some hopeful observations on a possible example of biological control of Burmese pythons. Using motion sensitive cameras positioned around a python’s nest in the Big Cypress National Preserve in Florida, the scientists watched a 20 pound bobcat repeatedly visit the nest while the female python was away and eat 42 of the eggs in the python’s clutch. The bobcat also damaged (rendering them inviable) 22 other eggs in the nest! After several successful nest visits, the bobcat then encountered the female python and quickly departed only to return later to have a direct interaction with the 115 pound snake. The python lunged at the bobcat (and missed) and the bobcat struck at the snake’s head with his claws (and also missed).

This python/bobcat encounter was described in a February 19, 2022 article in the journal, Ecology and Evolution.

Amazingly, these huge Burmese pythons are very difficult to find in the field. They have excellent camouflaging coloration and tend to remain quite motionless as they wait, concealed in murky water or in thick vegetation, for potential prey to come within their strike ranges. One very common, natural resident of the Everglades, though, can quite easily find these large snakes and can use them as a food source to drive their reproductive biology. Anyone who has ever been to the Everglades is very familiar with the abundance and aggressiveness of these blood seeking creatures: mosquitoes!

Using simple mosquito funnel traps ,entomologists can collect samples of mosquito populations across very broad areas. Female mosquitoes after taking a blood meal, retain that blood in their digestive tracts for a significant amount of time, and this blood can be analyzed for the presence of python DNA. If this DNA is detected, then, there must be a python within the hunting area of those mosquitoes and snake hunters can go out with a significant edge in their search for these invasive reptiles!

Previously, we have talked about “environmental DNA” (“eDNA”). This is DNA from plants, animals and fungi that has been shed from the body of one of these organisms and is then present in water, air or on some environmental surface (see  Signs of Spring 3, March 24, 2022). The eDNA that is accumulated in, and then recovered from some blood feeding invertebrate is referred to as “invertebrate DNA” or, iDNA).   This type of DNA is not only useful in hunting for Burmese pythons, but it is may also be used to answer much more complex, ecological questions.

Tiger leech. Photo by D. Culbert, Wikimedia Commons

In the March 23, 2022 issue of Nature Communications, a group of scientists from the Kunming Institute of Zoology teamed up with park rangers in China’s Ailaoshan Nature Reserve and collected leeches throughout the reserve. Over the three month sampling period, 30,468 leeches were collected. The blood inside the collected leeches was sampled for iDNA, and a total of 86 different animal species were identified. These species ranged from domestic livestock (cattle, sheep and goats), humans, Asiatic brown bears and endangered, Yunnan spiny frogs!

Analysis of the abundance and distribution of this iDNA enabled the Kunming Institute scientists to construct models of animal distribution, movement and interactions throughout the reserve. Of particular note was the observed antagonism between both livestock and humans and wild species. Any area that was used for livestock grazing or frequented by people, had very low numbers and diversities of wild animals.

The low cost of this type of collection system and its ease of application coupled with the richness and detail of the data generated, makes iDNA sampling a valuable tool in both the detection of feral, exotic species and also in the study of native, wild animal populations!

Mus muscularis. Photo by G. Shutlin, Wikimedia Commons

(To listen to an audio version of this blog, click on the following link….Mouse hairs, octopus brains and talking mushrooms

Recent articles in The New York Times and The Scientist described a paper written by a British defense industry physicist, Ian Baker, whose research area is infrared sensors. The paper (published in the December 8, 2021 issue of the Royal Society Open Science) described the extensive infra-red observations Baker made on the nighttime behaviors and activities of animals living in the diverse field and wooded habitats near his home. Using his highly advanced infra-red cameras, he observed numerous small mammals (including a number of species of mice, shrews, voles, squirrels, hares and rabbits) and also several of their predators (specifically, domestic cats and barn owls).

Figure by I. M. Baker. R. Soc. Open Sci. 8, 210740

Baker noted that the cats and barn owls seem to assume quite exaggerated body positions when hunting for and lunging at their prey. These body positions (the cats hunched back behind their cold noses and the owls twisted and folded up to hide their faces and legs) seem, on Baker’s outstanding thermal photographs, to function to conceal the heat signature features of the predator’s body from their prospective prey. Baker wondered why they would be doing this?

Infrared sensor-like hairs of the common shrew. Figure by I. M. Baker. R. Soc. Open Sci. 8, 210740

Baker then examined the microscopic structure of the guard hairs on the backs of diverse group of potential prey species and found a curious, but very consistent feature: the hairs all had regular arrangements of bands of pigments along the length of their shafts. Further, this band pattern was quite familiar to Baker: it was the same banded pattern found in his own thermal sensors that were tuned to specific wavelengths of electromagnetic (EM) radiation! Specifically, the band pattern in these guard hairs were identical to those in thermal sensors designed to detect EM radiation with wavelengths of 10 microns. This wavelength is in the mid-infrared region and is also the most typical infrared heat signature of a mammalian or avian body.

Baker hypothesizes that the banded guard hairs on his mice, voles etc. are in fact sensory receptors designed to detect the infrared body signature of an approaching predator. If this hypothesis is correct, then these prey species have a “360 degree sensory shield” that helps to protect them from predators. More research is called for to examine the neural connections of these guard hairs to determine if, indeed, they transduce heat signals into sensory nerve impulses.

Day octopus, Photo by M. Tattersail. Flickr

I have written about the intelligence of octopuses and other members of Class Cephalopoda before (see Signs of Summer 1, June 3, 2021). Many lists of the “most  intelligent animals” put octopuses among the top ten most intelligent organisms in all of Nature! They are typically ranked as being more intelligent than dogs or cats, but slightly less intelligent than chimpanzees, orangutans, elephants or dolphins! They are, without question, however, the most intelligent, group of invertebrates on Earth! Octopus brains, though, have not been extensively studied using some of the newest tools of neurobiology.

On average, octopus brains contain a little over 500 million neurons! That’s comparable to the number of neurons found in a dog’s brain. It is possible, though, as I mentioned in my June 3, 2021 blog, that due to the incredible diversity of types of cellular junctions seen in octopus neurons, that the octopus neuron-network is more both more efficiently and more complexly interconnected than those found in mammalian species with comparable numbers of neurons.

Vampire squid, Photo by MBAR, Wikimedia Commons

A research team at the University of Queensland (Australia) Brain Institute explored the brain anatomy of four cephalopod species using advanced Magnetic Resonance Imaging (MRI) technology. Their results were published in the November 18, 2021 issue of Current Biology. The selected cephalopod species were from a broad range of habitats and exhibited a number of different behaviors and ecological roles. The organisms in the study included the vampire squid (Vampyropteuthis infernalis) (a deep ocean species), the blue lined octopus (Hapalochlaena fasciata) (a solitary, nocturnal species), the algal octopus (Abdopus capricornicus)  and the day octopus (Octopus cyanea) which are both diurnal species found in complex, species-rich reef ecosystems.

The findings of this study were quite logical, but also quite elegant. The optic lobes of the brains in the vampire squid and the blue lined octopus were much smaller and less complex than the optic lobes in the algal and day octopuses. The importance of vision and visual memory in these two diurnal predators was clearly correlated with their MRI’s. Also, the vertical lobes of the algal and day octopuses were larger and more complexly folded than either the vampire squid or the blue lined octopuses. The vertical lobe is involved with memory and learning and undoubtedly helps these two, diurnal octopuses develop and carry out complex tasks both in hunting for prey and avoiding becoming prey for other, larger predators.

This study clearly correlated the ecological roles and requirements of these cephalopod species with the development and evolution of their complex brains. There are about 800 living cephalopod species doing all sorts of activities in their very diverse environments. Let’s hope that neurobiologists continue to explore these as yet unexamined brains in order to generate a more complete picture of the evolution of invertebrate intelligence!

Forest mushroom, Public Domain

I have written about fungi before (Signs of Spring 10, May 3, 2018). I have looked at fungi from an ecological point of view discussing their ability in soil ecosystems to form mycorrhizal, symbiotic networks with plant roots that enable plants to more efficiently gather nutrients and the fungi to gather energy molecules from the plants. I have also talked about the chemical diversity of fungi (and especially their mushrooms) and some of the research exploring the use of these chemicals as medicinal drugs to benefit human health. I have also talked about gathering wild mushrooms for food (and fun!). A recent research paper, though, in the Royal Society Open Science (April 6, 2020) explored a feature of fungi that I didn’t have any idea existed: how they “talk” to each other!

Fungal hyphae mass. Photo by S. Thimmiah, Wikimedia Commons

Fungal hyphae (the long, thin, cellular “threads” that a fungus forms as it grows through its environment) make interconnections with other fungi and also with plant roots. The Fungus/plant interconnections are the mutualistic mycorrhizae mentioned above. Hyphae are capable of generating electrical impulses similar to the action potentials seen in nerve fibers. Researchers at the Unconventional Computing Laboratory at the University of the West of England used micro-electrodes to monitor the hyphal electrical impulses of four common mushrooms (enoki, split gill, ghost and caterpillar fungi). Their observations suggest that the electrical impulses being produced by these fungi are not random by-products of some other metabolic processes. Instead, there were distinct patterns to the impulses that suggested an organized “vocabulary” of some 50 “words!”

If these electrical impulses are, indeed, words, what could these fungi be talking about? What information would be so valuable to a community of fungi that could account for the large metabolic expense required to both run and recover from these electrical cascades? What natural selection system could explain the elaborate, evolutionary steps and sequences required to construct these electrical generating systems?

Can we expect to be able to translate these fungal “words” into a human language?  Would they make any sense to us at all? Probably not. As the philosopher Ludwig Wittgenstein put it, “If a lion could speak, we could not understand him.” And, a fungus is much more alien to us than a lion!

Utah juniper tree. Photo by A. Levine, Wikimedia Commons

(Click on the following link to listen to an audio version of this blog … Junipers and potholes )

Edward Abby had more than a couple of things to say about juniper trees in his book Desert Solitaire:

“The essence of the juniper continues to elude me unless, as I presently suspect, its surface is also its essence.”

“If a man knew enough he could write a whole book about the juniper tree. Not juniper trees in general but that one particular tree which grows from a ledge of naked sandstone near the old entrance to Arches National Monument.”

Junipers stand out against the rocky expanse of the Colorado Plateau steppes. Their deep, living green contrasts with the tans and red-browns of the sand and rocks and with the gray-greens of the scattered sagebrush. That they can live here on the edge of the desert, that they can exist where almost no other green thing can, is a story worth exploring. They stand, as Abby implied, at the edge of an infinite complexity of wonder!

Photo by D. Sillman

There are two common species of juniper around Arches and Canyonlands National Parks: Utah juniper (Juniperus osteosperma) and one-seed juniper (J. monosperma). These two species resemble each other: both have short, straight trunks with spreading branches, very small, yellow-green, scale-like leaves (on adult trees) and light blue “berries”  (which are really ripe, wax-encased, seed cones). On very young seedlings the leaves are green, needle-shaped and just under 1/2” long.  One-seed juniper trees are usually smaller and bushier than Utah junipers. Also, their “berries” are usually slightly smaller. The two trees, though, are very difficult to tell apart, and, making absolute identification even more challenging, the two species also cross-pollinate and form intermediately configured hybrids.

These junipers can be between 10 and 26 feet tall, and, like sagebrush, have two types of root systems: a deep taproot that can be up to 25 feet long, and a shallow, spreading fibrous root system that can extend up to 100 feet around the plant. The tap root allows the juniper to access water from the underlying water table and the fibrous roots enable it to take up rainwater and snow melt before it gets into the deep water table. Interestingly, the fibrous root systems are inactive in the summer (a time when there are few rain events). Snow melt is probably the main source of water picked up by these shallow, fibrous roots.

Utah juniper. Photo by fcb981. Wikimedia Commons

Junipers grow very slowly and add only 0.05” to their trunk diameters each year. They are, however, very long-lived and can reach ages in excess of 650 years!

Junipers are mostly monecious (only one type of individual that has both pollen and ovulate cones). They begin to produce seeds at 30 years of age and, thereafter, make abundant seeds almost every year. Each “berry” contains one or two seeds. Many mammalian and avian species rely on juniper “berries” for food, and the juniper in turn relies on these consumers to transport and disperse the seeds and also scarify them. Juniper seeds germinate much more readily after they have passed through the intestines of a seed-eating mammal or bird.

Junipers also often have white berries growing among their dense branches. These are the fruits of two mistletoe species (juniper mistletoe (Phoradendron juniperum, ssp juniperum) and dense mistletoe (P. boleanum ssp densum)) which very commonly parasitize both Utah and one-seed junipers.

Pinyon-juniper woodland shrubland. NPS, Public Domain

Junipers are most often are found growing with pinyon pines (Pinus edulis). These pinyon-juniper woodlands are quite productive and are expanding into formerly sagebrush areas primarily due to human activity (see Signs of Summer 6, June 23, 2022). Suppression of natural fires has allowed some sagebrush communities, which historically got “re-set” every few decades by burns, to develop into pinyon-juniper woodlands. And, the more intense and more frequent occurrence of modern wildfires (fueled by the presence of invasive species and the extended dryness and heat due to climate change) have wiped out unnaturally large areas of sagebrush leaving little chance of natural re-vegetation with seeds from the poorly transported sagebrush species.

Young juniper trees are very vulnerable to fire and are easily killed in even low intensity fires. Older, larger trees have some resistance to fire damage. Natural fires in pinyon-juniper woodlands have historically cycled over every 10 to 30 years.

Pronghorn Antelope, Cabin Lake Road, Fort Rock, Oregon

Many small mammals (including desert cottontails, porcupines, deer mice, Great Basin pocket mice, desert woodrats and kangaroo rats), and reptiles (including collared lizards, plateau lizards and tree lizards) rely on pinyon-juniper woodlands for habitat. Also over 70 species of birds breed in pinyon-juniper woodlands including five species that locally do so obligatorily (screech owls, gray flycatcher, scrub jay, plain titmouse and gray vireo). Ferruginous hawks also nest in Utah juniper trees.

Large mammals (like mule deer, elk, bison, pronghorns, wild horses, mountain lions and lynx) also inhabit pinyon-juniper woodlands. These woodlands provide these species very important protective cover both in the summer and in the winter.

Photo by D. Sillman

Juniper leaves are very poor quality browse. They are quite low in nutrients and have high levels of volatile oils which can poison a ruminant’s vital stomach microflora. In the winter, though, when browse is scare, mule deer do consume juniper foliage.

A very unusual feature of a juniper is its ability to prune back its own branches in order to conserve water. Most older juniper trees have large, dead branches still attached to the main, living trunk of the tree. The trees are able to shut down waterflow to those branches in order to keep sufficient water available for the rest of its tissues.

Dry potholes at Grand View Point. Photo by M. Hamilton

When we were out on the big, slick-rock expanse looking over the canyon at Grand View Point, I noticed a whole set of crust-lined concavities all across the rock. The depressions were between 3 and 8 feet long and each one was about half as wide as it was long. The largest of the “potholes” had depths of 4 or 5 inches below the rock-face surface at their deepest points with much shallower areas around their peripheries. All of them, though, regardless of size, were uniformly lined with similar-looking, flaky, greenish-gray coatings.

There were about 20 of these concavities immediately visible across the open rock face where I was standing but many more off in the more vegetated (juniper trees and black-brush clumps, primarily) edges of the rock. There were a very large number of these concavities, then, all along the rocky top rim of this canyon!

Potholes in sandstone. J. St. John. Flickr.

Using some very rusty geometry, I calculated that the larger holes had individual volumes of about 31 gallons (or 117 liters), and that the smaller ones were closer to ten gallons (or 38 liters).  All of the depressions I could see had a summed volume of just over 400 gallons, but this volume represented just a fraction of the total potential pool size across the miles and miles of rock circling the top rim of the canyon. These little “potholes” could collectively hold a very large volume of water from snow melt or spring rains!

These potholes, when filled with water, are called “desert rock pools” or “freshwater rock pools.” They are the desert counterpart of the temporary, “vernal” pools found in the wet forests of the eastern part of North America (see Signs of Spring 10, April 28, 2016) or, maybe more accurately, miniature versions of the playa lakes of the southern plains (See Signs of Winter 4, December 24, 2020). They are extremely ephemeral bodies of water in a climate where water is the preeminent ecological limiting factor.

These rock pools are miniature, oligotrophic (“low nutrient”) ponds. Nutrients in them can only come from air-borne organic materials or from feces deposited by terrestrial animals. Primary productivity (photosynthesis) in the pools is quite limited and for the most part carried out by cyanobacteria. As we saw in biological soil crusts, cyanobacteria are able to survive severe desiccation and can rehydrate quickly back into fully functional, photosynthesizing cells. The bottom crusts of the dried pools are, for the most part, cyanobacteria residues. We should also note that, like the cyanobacteria residues in biological soil crusts, these rock pool residues are very susceptible to compression damage! Walking or wading through one of these pools can do a great deal of lasting damage to these vital bacteria.

Utah desert rock pools. Needpix.

When one of these pools fills with water a number of species of crustaceans, flatworms, rotifers, mites and tardigrades rush to complete their life cycles. As the water evaporates, these organisms, if they have developed quickly enough, sink back into their drought resistant life stages (eggs, larva or even adult forms) and bury themselves in the dry, protective crust of the pool’s sediment.

These “passive dispersing” life forms move from pool to potential pool by high, seasonal water flows or wind. Animals walking through the dried crusts can also transport the active or inactive life stages of these organisms from one pool site to another.

The pool also sustains a number of “active dispersing” species. These include many species of flies, midges and mosquitoes whose adult forms can fly from pool to pool to lay eggs. We were cautioned that in the early spring there are large numbers of biting midges out on the hiking trails of Arches and Canyonlands. These rock pools are, undoubtedly, one of the main sources of these organisms.

These pools are important signs of the overall health of these desert and dry steppe ecosystems. They are also quite important, in spite of their incredibly short-lived natures, in the early spring food chains for a number of bird and reptile species. The clouds of midges and mosquitoes to us humans are pests, but to a hungry, nesting, insectivorous bird or hunting lizard, they are mana from heaven (see Signs of Spring 13, May 19, 2015)!

Raven at Landscape Arch Trail. Photo by L. Drake

I had a few more “Moab” topics that I wanted to write about, but five blogs (7500 words) about these Utah ecosystems seems like enough for now! Sometime in the future I will write about ravens and cliff swallows, packrats and quicksand, and yuccas, Mormon tea and prickly pears! I’ll also try to get all of the incredible plant pictures that Deborah and Marian took and identified, organized and published. Stay tuned!!

“Desert” vegetation. Photo by D. Sillman

(Click on the following link to listen to an audio version of this blog …. Biological soil crusts, rock varnishes and kangaroo rats )

One of the main distinctions between an arid grassland and a desert is the abundance of bare soil in between a desert’s isolated clusters of plants. For centuries it has been recognized that these desert soils were not just random mixes of simple soil separates (sand, silt and clay particles). Instead, this soil was darker than it would be if it were only made up of soil particles. It was also lumpy and in a micro-topographic way, complexly structured with tiny turrets, folds, mounds and crevices. Initial names for these dryland soils often had the prefix “crypto” appended to them implying that they had a mysterious or hidden nature. They were, though, just sitting there out in the open waiting for detailed examination and description.

Cyanobacteria filaments. Photo by J. Golden, Flickr

Research teams of botanists and agronomists finally began to peel away the “crypto” nature of these dry soils in the late 1970’s and showed them to be complex micro-communities dominated by cyanobacteria (“blue-green algae,” one of the oldest photosynthesizing organisms on Earth (see Signs of Winter 9, February 13, 2020, and Signs of Summer 16, September 17, 2020)). These soil surface communities also contained green algae, lichens, fungi, mosses and a variety of other species of bacteria. All of these living organisms acted to stabilize the desert soil and nurture the surrounding plants in entirely unexpected ways. These thin, delicate encrustations, now called “biological soil crusts” (or, “biocrusts”) were, in fact, the living “top soil” of the desert! These patches of “bare” soil, in fact, contained more species than could be found in all of the surrounding desert vegetation!

Soil crust magnified 90X. USGS. Public Domain

Cyanobacteria make up to 95% of the biomass of a biocrust. These photosynthetic bacteria grow in long, filamentous strands that are woven around the individual soil particles. They need to keep themselves exposed to sunlight in order to power their photosynthetic metabolisms (so they can’t go very deep into the soil profile!). Cyanobacteria can tolerate extreme desiccation and are able to rapidly re-hydrate when moisture once again becomes available.  Dried filaments, when they re-hydrate, swell to ten times their desiccated volume thus storing a large volume of vital soil water. New filaments are slowly added to the fiber systems and, over years and decades and even centuries, the soil particles become tightly woven into a complex bacterial framework. The cyanobacterial filaments also secrete sheathes of mucopolysaccharides which act to further bind the soil separates together. These extracellular mucopolysaccharides persist and continue to cement the soil components together even during period of extreme filament desiccation.

Biological soil crust at Arches N. P. Photo by D. Sillman

The impact of these filaments and sheaths on the soil is profound. Erosion both by wind and by water is significantly reduced in soils stabilized by these filaments. The potentially destructive impact of raindrops striking exposed soil is also reduced by the hard barrier of the crust, and the dark color of the crust absorbs sunlight and speeds up the thawing of the soil in the Spring.

The complex soil structure generated by these filaments and sheaths forms aeration and water flow channels through the crust. It also generates complex, raised edge depressions on the soil surface that allows surface water to pool up and then seep down slowly into the soil  profile rather than simply running off in surface flow. Also, a number of the bacteria in the crust are nitrogen fixers (they remove molecular nitrogen from the air and convert it into chemical forms that can be utilized by plants). For many desert plants, this is the only source of nitrogen available to them!

Biological soil crust at Arches N. P. Photo by USGS, Public Domain

The crust also serves as a nutrient bed within which the seeds of many plant species germinate. As these plants begin to grow, the crust with all of its spaces and channels also facilitates root growth.

Biological soil crusts once covered all of the dry, exposed soils of Colorado Plateau. Livestock trampling and human activities, though, have greatly reduced the distribution of these crusts. The cyanobacterial filaments and mucopolysaccharide sheaths are very sensitive to compressional damage. A single footprint can destroy all of the underlying soil crust filament infra-structure and leave a scar that takes decades to repair. “Don’t Crush the Crust” is a theme widely advertised on the hiking trails throughout the Plateau’s National Parks.

Rock varnishes near Moab, Utah. Deborah in the foreground. Photo by M. Hamilton

Rock varnishes are thin, dark or reddish-brown coatings on desert rocks and cliff faces that were once thought to have origins similar to those of biological soil crusts. Recent research, though, has clearly shown that these hair-thin patinas, usually found on very sheltered rocks, are chemical in their origin rather than biological.

Rock varnishes (also called “desert varnishes,” or “rock rusts”) form when silica atoms either in the atmosphere or from the underlying rock itself slowly

Desert varnish. Photo by Ooinn, Wikimedia Commons

accumulate on the rock surface and weather into a stable, dry gel. This process is very slow and may occur over centuries or even millennia. The color of the varnishes often reflect the presence of iron oxides (reddish brown) or manganese oxides (black). There is an on-going debate about whether biological processes may play a role in accumulating these metallic oxides within the predominantly chemically generated films.

A remarkable feature of these gelled silica layers is that they trap biological materials in between their forming layers. Amino acids, fragments of DNA and even entire bacterial cells can be found encased between the microscopic silica layers of the varnishes! Analysis of the trapped materials in a rock varnish may reveal information about ecosystems and climates that existed on these sites thousands or even millions of years ago.

Native American petroglyphs (Newspaper Rock, southeastern Utah). Photo by J. St. John, Wikimedia Commons

Desert dwelling people use the rock varnishes as a canvas to etch art that depicted their lives and activities. The petroglyphs found throughout the American Southwest are examples of these “enhanced” desert varnishes!

Rock varnishes may also be present on rocks on Mars! New NASA probes and rovers exploring the Martian surface are programed to look for stained rocks and maybe even sample them as a way to explore the ancient history (and, possibly, the ancient biology?) of Mars!.

Kangaroo rats are creatures of the desert that are behaviorally and physiologically adapted to extremely dry conditions. The are primarily nocturnal and spend the hot, dry days sealed up in their cool, highly branched burrows about a foot or so underground. Their respiratory systems have long, upper respiratory tubes that are designed to minimize water loss during expiration, and their excretory and digestive systems are designed to form extremely concentrated, low moisture urine and feces. Kangaroo rats also never drink liquid water! They generate water metabolically from the carbohydrates and to a lesser degree fats in the seeds they eat.

Ord’s kangaroo rat, Photo by A. Teucher, Flickr

Ord’s kangaroo rat ((Dipodomys ordii) is very common in Arches and Canyonlands National Parks. This kangaroo rat is vital to the propagation and, possibly to the very existence of an important desert grass called “Indian rice grass” (Achnatherum hymenoides). Indian rice grass is a common, desert bunch grass that makes very large seeds (about half the length of a rice grain) in the late spring or early summer. Many wildlife species rely on rice grass seeds for food including Ord’s kangaroo rat.

Ord’s kangaroo rats gather the fallen Indian rice grass seeds in the summer and cache large percentages of them in shallow (three-inch deep) burrows. This depth, it turns out is ideal for these seeds to germinate! Further, the rats as they pick up and stuff the rice grass seeds into their cheek pouches for transport, scratch away the heavy protective coat on the seeds making them primed for immediate germination. Without this physical scarification, the rice grass seeds might remain dormant for years before germination!

The kangaroo rats gather and cache such an abundance of seeds, that the rats only recover about a third of them. The unharvested seed caches then germinate and grow into new clusters of Indian rice grass. It is estimated that 90% of Indian rice grass plants growing across the Colorado Plateau originate from Ord’s kangaroo rat seed caches!

Ord’s kangaroo rat,. NPS, Public Domain.

Kangaroo rats have very large back feet that they use for their “kangaroo-like” locomotory system of leaping and bounding. They also have very long tails with bushy ends that they use to keep their balance during their energetic jumps and leaps. Adult kangaroo rats are solitary and extremely antagonistic toward each other. This antisocial behavior, though, is quite adaptive in that it helps to keep kangaroo rat densities low in their resource-poor habitats.

I really didn’t expect to see any kangaroo rats on our Utah trip. Most of our hiking and outings were going to be during daylight hours, and kangaroo rats, like most desert animals, are well tucked away out of the reach of the hot desert sun during the day. However, the weather for most of our hikes was very mild (high temperatures only in the 70’s) and, like many species scrambling for limited resources, kangaroo rats can come out in the daylight if there is a good possibility of food.

Grand View Point, Canyonlands N. P. Photo by L. Drake

We were up on the rim of Grand View Point, seated on some well placed boulders that were scattered across a broad, slick rock base. The view across the canyon toward the distant confluence of the Green and the Colorado Rivers was breathtaking. We, and a number of other hikers, had stopped to have lunch and were subsequently entertained by the antics of two kangaroo rats who scuttled between the shady cover of the juniper and black-brush that were growing out of the creases and cracks in the rock. The rats, leaped here and there and chased each other about, but always kept their eyes open for any fallen bits of trail mix or sandwich crumbs.

Ari and I on a rock at Grand View Point. Photo by M. Hamilton

My grandson Ari and I were sharing a big sitting rock and had finished our peanut butter-and-jelly sandwiches. We split a handful of salted nuts for desert and several of nuts fell to the ground and rolled over to the edge of a black-brush bush. None of the lurking rats seemed to immediately notice the fallen nuts. After we finished our share of the nuts, though, we walked over to the edge of the canyon to take in the view. When we returned a few minutes later, all of the fallen nuts were gone. A lunch fit for a kangaroo rat!

I hope that they didn’t just bury them and forget where they are!

(Next week: juniper tree and desert potholes!)

Vegetation in Arches National Park. Photo by D. Sillman

(Click on the following link to listen to an audio version of this blog … Sagebrush )

When we drove out of the Rocky Mountains via Glenwood Canyon, we entered the sagebrush lands of Colorado Plateau. Big sagebrush (Artemisia  tridentata) is one of the more notable species of sagebrush found all across these arid, western plains. Sagebrush is not technically a desert plant, though, instead, it is considered to be a vital member of the dry, steppe plant community (steppes receive slightly more rain (7 to 16 inches per year) than deserts (which receive less than 10 inches of rain per year). Sagebrush is found from Nebraska to California and from New Mexico to Montana. It has the widest distribution of any shrub in North America.

There is a wide range of estimates of the area of western North America that was once covered with sagebrush. A frequently mentioned value, though, is 422,000 square miles (270 million acres), a very large chunk of the American west! Regardless of how much sagebrush we started with, though, most experts agree that to date, more than half of the original, pre-settlement sagebrush acreage has been lost primarily due to land clearing for agriculture and various range “improvements” for livestock forage. Also, unnaturally extensive and intense wildfires, driven in part by climate change, have also destroyed millions of acres of sagebrush (more on this below).

Big sagebrush. Photo by DcrJsr, Wikimedia Commons

Big sagebrush (and other sagebrush species) were once classified as an undesirable “range weeds” by the United States Department of Agriculture (USDA), and land managers were encouraged to eradicate them. More recently, however, the true nature of sagebrush has come to light. The presence of these tall, evergreen shrubs in their arid habitats, generates microenvironments under them, within them and around them that are favorable and sometimes even vital for the existence of hundreds of species of plants and animals. Big sagebrush is, quite decidedly, a keystone species in its biological community!

Writing in a series of USDA Technical reports in the early 2000’s, B. L. Welch compared the soil and plant communities under or near sagebrush with those away from the sagebrush cover and noted that in the proximity of sagebrush, plant diversity and abundance were higher, soil moisture and nutrient levels were higher and the growing season for plants was 28 days longer.

Sage grouse. Photo by USFWS, Public Domain

Welch further listed animals that were obligatorily dependent on sagebrush for their survival (including the greater sage grouse, Gunnison’s sage grouse, sage sparrow, Brewer’s sparrow, sage thrasher, pygmy rabbit and sagebrush vole). He also noted that 100 species of birds, 90 species of mammals, 60 species of reptiles and amphibians are at least partially dependent on sagebrush for food, habitat, reproductive sites and as a refuge from the extreme heat of the dry steppe environment. Also, 240 species of insects, 70 species of spiders and other arachnids, 133 species of plants (including 23 species of root hemi-parasitic paintbrushes and owl-clovers) and 24 species of lichen were associated with and benefited by sagebrush.  He also described the synergy between the sagebrush micro-community and the surrounding, soil surface  “biological crust.” (We will talk about biological crusts next week!)

Big sagebrush gets its species name (“tridentata”) from its three-pronged leaves. The leaves are small and are directly attached to nodes on its stem. They are also covered with fine, silvery hairs. The small size, the tight stem attachments and the covering hairs all help to reduce transpiration water loss from the leaves and increase the fitness of the plant in its very dry environment.

Photo by M. Lavin, Wikimedia Commons

Big sagebrush can be a foot and a half to over nine feet tall depending on the richness and, especially, the moisture levels of its soil. Big sagebrush can also have a very long lifespan with some plants reaching 100 years of age! Big sagebrush has two types of roots: a dense shallow set that quickly gathers any incoming precipitation from the surrounding soil surface, and a deep taproot that reaches down 3 to 15 feet often reaching the underlying water table. These tap roots brings up “deep water” that not only satisfies the sagebrush’s own water needs but also provides moisture to nearby plants. European settlers looking to establish farms in the dry steppes of the American southwest, looked for tall, big sagebrush as indicators of a deep, non-acidic soils with, potentially, high soil fertility.

Big sagebrush’s silver-grey leaves have an herbal, almost spicy aroma due to an abundance of secondary chemicals like camphor, terpenoids and a number of other volatile oils. The purpose of these chemicals is to protect the leaves from grazers and browsers and also, possibly, to serve as communication chemicals between plants (when a sagebrush is disturbed by a grazer, it releases a cloud of camphor and terpenoids which stimulate nearby plants to make more of these grazer-repellant chemicals).

Pronghorn Antelope, Photo by A. Wilson, Wikimedia Commons

Big sagebrush leaves are rich in protein (16%), fats (15%) an carbohydrates (47%) and are actually more nutritious than alfalfa! Domestic livestock, though, is not able to consume big sagebrush because of its volatile chemicals. This intolerance explains why many ranchers have treated sagebrush as a noxious weed! A number of native species (like deer, moose, elk, and especially, pronghorns and bighorn sheep) can, at need, eat big sagebrush leaves especially in the winter. One reference stated that these native species “belch off” the volatile secondary chemicals before they can poison their vital, mutualistic, gut bacteria. Sage grouse also readily eat sagebrush leaves (sagebrush leaves make up 60 to 80% of the sage grouses’ year-round diet). The absence of  gizzard in the sage grouse, apparently, allows the sagebrush leaves to pass through their digestive systems without excessive physical disturbance that would release the toxic, volatile chemicals from the leaf tissues.

Big sagebrush, Public Domain

The flowers of big sagebrush develop on stalks that rise up from its upper branches. The flowers are small, yellow and wind pollinated. Pollen is produced in great quantities in August and September and is a very well recognized cause of fall allergies. Abundant seeds are produced as a consequence of this pollination (up to 350,000 per plant). Seeds are dispersed by gravity and wind and also by ants (in particular, the western harvester ant (Pogonomyrex occidentalis)). Native Americans harvested the very abundant big

Flowering sagebrush. Photo by M. Harte, Forestry Images

sagebrush seeds and ground them to make a flour.

Sagebrush is able to reproduce both by seed and also by stem-sprouting from its underground rhizome. New plants arising from seed require much higher amounts of moisture than plants arising from root sprouts. The “mother” plant of these sprouts, apparently, provides both water and nutrients to its clonal offspring giving them a growth edge over seed-derived, sagebrush seedlings and also other plants. Seed dispersal into burn areas, however, is vital for sagebrush recovery following a wildfire.

Fire is a normal component of a natural sagebrush ecosystem. The abundance of oils in the tissues of sagebrush plants make them extremely flammable even when they are green and healthy. “Natural” fires, though, in a sagebrush community are usually rather limited in total land area that is burned, and they are of rather low, overall intensity. These “natural” fires historically occurred every 60 to 110 years, and once an area burned, it was quickly re-seeded with sagebrush from nearby, surrounding plants. The cycling of these natural fires created natural sagebrush ecosystems that were patchworks of differentially aged communities. It also kept the vegetative systems in sagebrush configurations. Suppression of these natural wildfires through human intervention, however, broke this ecological re-set pattern and caused aging, sagebrush communities to be replaced via succession by woodlands of pinyon pine and juniper. Millions of acres of sagebrush have been lost to pinyon-juniper forests because of the human interference in the natural fire cycle.

Cheat grass. Photo by S. Dewey, Utah State University, Bugwood.org

Modern fires in sagebrush habitats are quite different from historical, natural fires. Climate change has caused prolonged drought periods  and elevated summer temperatures throughout the west. These conditions have caused the sagebrush vegetative community to become very dry over very extended periods of time. Also, the modern sagebrush plant community now includes a number of invasive plant species that add considerably to the overall quantity of fuel available to support and feed a wildfire. In particular, the exotic invasive “cheat grass” (Bromos tectorum) is found abundantly throughout sagebrush areas. Cheat grass was accidently introduced to wheat fields in the United States in the late 19^th Century and has spread widely and rapidly across the west. When we were in Utah we saw cheat grass growing in the vegetative communities throughout the national parks. We even saw waves of cheat grass growing up through the dry, barren gravel of a number of parking areas! It is a tenacious and highly drought-tolerant weed!

Cheat grass- assisted wildfires burn much hotter than “natural” wildfires. They also burn over much more extensive areas. These expanded burn areas, then, are not efficiently re-seeded with sagebrush because of the greater distance the poorly transported sagebrush seeds must travel.  Also, because these cheat-grass assisted fires occur much more frequently than natural fires (the new fire cycle repeats itself, on average, every 5 years!) they eliminate any early, vegetative re-growth and very effectively prevent the sagebrush community from becoming re-established. Sagebrush, amazingly, is under a distinct extinction threat from these climate and invasive species augmented fires!