Ecologist's Notebook

Black rat. Photo by Kilessan. Wikimedia Commons

(Click on the folowing link to listen to an audio version of this blog ….Seattle Rats (the black rat)

In the previous blog we talked about the brown rat (Rattus norvegicus) and its abundance and dominance in Seattle’s urban ecosystems. The brown rat’s “companion rat” in our Seattle neighborhoods is the “black rat” (Rattus rattus). Both types of rats are “Old World” rats that came to the coastal areas of the Pacific Northwest on ships carrying cargo and people to the busy ports around Puget Sound.

Seattle and its invasive rats are a microcosm of port cities all around the world. For centuries  ships have delivered an incredible diversity of cargos, and traveling along with all of the finished goods and raw materials were stowaway species like the brown and black rat. When these species jumped ship, they either found open niches in their new homes in which they thrived, or they carved out niches previously occupied by weaker species. Either way, once they got a claw-hold on a site, they were nearly impossible to dislodge! The brown rat and the black rat, because of their affinities for human beings, their ability to survive on ships, their aggressiveness, their nearly perfect omnivorous life strategies and their fantastic rates of reproduction quickly became the two most abundant rat species in the world!

According to historical records, Seattle was initially a black rat paradise. The abundance of wooden structures in the city most of which were roofed with thatch and sticks provided the agile black rat with an extensive, above ground habitat in which it could nest, hide and thrive. As the city grew, though, and some say because of the Great Seattle Fire of 1889 which wiped out a great deal of these wooden houses and buildings, new buildings made of brick, stone and tile provided less habitat for the black rat and allowed the ground burrowing brown rat to become ascendent.

Black rat. Photo by J. Bailey. Atlas of Living Australia.

The black rat is also called the “roof rat,” the “ship rat” or the “house rat.” Its body is significantly shorter and more slender than the body of a brown rat (it is 5 to 7” long compared to the 9 or 10” body length of the brown rat). The tail of a black rat, though, is much longer (it has s tail that is up to 9” long compared to the 7 inch tail in the brown rat). This extremely long tail is the most obvious physical feature of a black rat.

Black rats are native to India and Southeast Asia. They spread extensively with movements of people and migrated over considerable distances during the Roman Empire possibly because of the Empire’s robust transportation system for grain. When shipping became a more common mode of transportation, black rats readily took to the ships and the high seas and, as mentioned above, spread over the entire globe.

Black rats like warmer habitats than brown rats and are less able to tolerate very cold winters or exposed conditions. Black rats carry large numbers of disease-causing bacteria in their blood streams and can transmit these diseases (including Yersinia pestis, the bacterium that causes bubonic plague) to each other and to other mammals (including humans) via their feces and via blood-feeding ectoparasites (like fleas). Some of the great plagues that have afflicted humans are attributable to the pathogens carried and distributed by black rats.

Black rat. Photo by H. Zell. Wikimedia Commons

Black rats prefer to live in the upper levels of houses and other buildings. They are often found in attics and in ceilings. They can very easily move across the upper limbs of trees and across the elevated wires of utility lines. In the wild, they are often found in cliffs or other types of rock formations or in trees (especially pine or palm trees). At need, they are also able to make burrows in the ground.

Black rats can eat almost anything and if left to themselves will choose foods and food combinations that are nutritionally balanced and healthy. They eat seeds, fruit, stems, leaves, fungi and a wide variety of invertebrate and vertebrate prey. In times of food abundance, they store excess food in caches. As an introduced, invasive species, the black rat’s extensive and voracious feeding behaviors can degrade vegetative habitats and directly and indirectly lead to the extinction of many vulnerable bird and small mammal species.

A number of predators take black rats for food. In urban environments domestic cats and dogs and owls eat black rats. A house cat is more likely to hunt and kill immature black rats because adult rats are typically too large to be taken by a normally sized cat. In the wild, weasels, foxes and coyotes hunt and kill black rats. Black rats, though, are not easily captured prey. Their excellent hearing and remarkable agility help them to avoid and elude many predators.

Black rats live in colonial groups that may contain several hundred individuals. These groups are extremely hierarchical and structured and have an older female at the apex of the social pyramid. This is an interesting contrast with brown rats whose colonies are controlled by apex males.

Dealing with rats can be a constant problem in any locale that has significant number of these rodents. The prime preventative directive for rat control is to prevent their access to food and water. Human and animal foods need to be stored in rat-proof containers. Rats can effortlessly chew their way into plastic, so often these containers must be glass or metal. Garbage must be contained in metal trash cans that have tightly locking lids. Racoons are able to tip over loosely lidded trash cans and will spill garbage for themselves and for any nearby rat. Anchoring or encasing the metal trash cans is another way to thwart this raccoon-rat symbiosis.

Food materials should not be added to outdoor compost piles. Bird feeders need to be rat-proofed with metal baffles and guards. Dogs and cats should always be fed indoors and their uneaten food must be picked up immediately. Dog feces must also be picked up and stored in rat-proof waste bins.

Black rat. Photo by Liftarn. Wikimedia Commons

Leaky water faucets should be repaired and any standing water should be cleaned up and dispersed. Wood and brush piles near the outer walls of houses or buildings also need to be clean up and removed.

To keep rats out of a building, all holes ¼” or greater in size need to be sealed up. Openings around drain pipes, vents and utility lines entering the house need to be tightly sealed and shielded. Pipes that run up the outside of a building must be blocked and vines growing on the outer walls of houses and buildings must be removed.  These pipes and vines can serve as vertical conduits for climbing rats and provide them access to the upper levels of a structure. Guards on utility lines, making sure all doors (including garage doors) tightly seal to the ground when closed will also help to keep rats outside.

It is hard to keep rats out of a house, but as someone once said, keeping rats out of a house is easier than getting established rats out!

So, Seattle! Rat City #12 (or so), USA!

Good thing that they are more and more coyotes here in the city or we’d be up to our necks in rats. A soon-to-come blog, by the way: Seattle coyotes!

Brown rat. Photo by Z. Cebeci. Wikimedia Commons

Click on the following link to listen to an audio version of this blog ….Seattle Rats (the brown rat)

If you ask a simple question, shouldn’t you expect to get a simple answer?

I wanted to know how many rats lived in Seattle, so I keyboarded the question into my favorite Seach Engine and fell down a rabbit hole nearly drowning in peripheral details. Precise numbers of rats, according to the merged wisdom of AI,  are not known because rats are very sneaky and very good at hiding and, so, are very hard to count. BUT, you can count the number of houses in a particular city that have reported having rats (to pest control companies or to the city authorities). For Seattle, that figure is 5.6% of all houses in the Seattle area. This puts Seattle at #11 on the American Housing Survey’s compiled list of “ratty” U.S. cities. The “winners” in this American Housing Listing were Boston (#1), Philadelphia (#2),  New York (#3) and Washington D. C. (#4).

Orkin, the pest control company, also generated a list of the most rat infested American cities. This list must have been based on specific calls to the company for rat mitigation (but they really weren’t terribly clear as to how they generated their data) . On this list Chicago was #1 followed by Los Angeles, New York, Washington D. C. and San Franciso. Seattle was #12 followed by Boston (our previous list topper) at #13.

Some casual comments about rat numbers in Seattle include “there are many more rats here than people.”   The human population of municipal Seattle is right around 800,000 but the population of greater Seattle (including Tacoma and Bellevue) is 4.15 million people! If everybody gets a rat or two, that’s a lot of rats!

Brown rat. Photo by C. Hamler. Wikimedia Commons

I think that the most accurate way to talk rat-numbers here in Seattle is to say they are hard to count but there are a lot of them! There are more rats than squirrels or cats or dogs. Maybe even more than all of the squirrles and cats and dogs put together!  No building or yard or empty lot is rat-free. They are everywhere! A few years ago I was standing in a bar down in Ballard and a brown rat quietly made his way across the center of the room. An odd choice for a rat-path since rats tend to stay near edges of open spaces and tend to hug walls. The rat and I made eye contact, and he stopped and looked at me with an incredibly human expression on his face. He seemed embarrassed and sorry to make a fuss. Then he dove under the skirting of the bar and was gone.

Brown rats (Rattus norvegicus) are the most common rat in Seattle and, the most common and most abundant rat in the world. Other common names for this species include “Norway rat” (because of some made-up nonsense that they came to England on a boatload of Norwegian lumber in the early 18^th Century), common rat, street rat, city rat, sewer rat, wharf rat and Hanover rat. Many of these names tell you about where this rat is most likely to be found (in urban areas on the ground and in sewers) and also highlight this species association with ships and transport. “Hanover rat,” apparently, was the original name applied to the brown rat by the English mixing the considerable disgust of the people with this destructive rodent and their near equal disgust of the German, royal House of Hanover.

Brown rat. Photo by Anemone Projector. Wikimedia Commons

Brown rats are 16” long with just under half of their length made up of their long, relatively hairless tail. Brown rats live on and in the ground. They have brown or dark gray fur on their backs and belly fur that is slightly lighter in color. They are vigorous burrowers and construct complex tunnels in the soil under buildings and in crawl spaces. These tunnels have nesting chambers that are often large enough for dozens of rats. They also have multiple exit tunnels to allow the rats to efficiently flee from dangers or disturbances.

Sewers are also a common habitat for brown rats. They are very strong swimmers and can swim or tread water for up to three days. A brown rat can also swim under water and is able to hold its breath for up to three minutes. This can allow a brown rat to actually swim up the sewer pipes and enter a building or a house via a toilet!

Brown rats live in extremely hierarchical colonies or communities. These communities can be relatively small (12 to 20 rats) or quite large (150 to 200 rats). A male brown rats sits at the apex of the community hierarchy. If food resources become limiting, a colony’s lower hierarchical individuals will experience a higher rate of starvation and mortality. Brown rats tend to be most active at night, and it is the lowest ranking individuals of the hierarchy that are seen out foraging in the daytime

A female (“doe”) brown rat can have up to five litters of young (“pups”) a year. Does reach sexual maturity by three or four months of age and can have litters throughout their three year (or so) lifespan. Each litter can have 7 to 14 pups. Immediately after giving birth a doe can again become inseminated and start her next litter even while nursing her previous one. The number of pups  in a litter and the rate of litter establishment is affected by the physical variables of the rat’s environment. For example, if the population numbers of the rat colony have decreased (because of increased predation or active pest control) the rate of reproduction will accelerate. The growth potential of a brown rat population is explosive!

Brown rat. Photo by R. Marshall. Wikimedia Commons

Brown rats are originally from Northern China. Their ability to live with humans (some would say their extreme affinity for humans!), their broad, generalist diet (they can eat almost anything), their extremely rapid rate of reproduction and their affinity with water (allowing them to travel on ocean-going ships and easily leave those ships to swim to land or to another ship in any port city of the world) have resulted in the distribution of the brown rat to all of the continents of the world except for Antarctica.

I recently read an account of Captain James Cook’s third voyage to the Pacific Ocean (1776 to 1779) (The Wide, Wide Sea  by Hampton Sides). Cook’s ship was invested with brown rats and to try to reduce their numbers, they anchored as close to shore as possible just off a whole array of pristine South Pacific and Hawaiian islands. The ship’s crew then chased as many rats as possible off of the ship. Cook, in his diary described hordes of rats diving off the ship into the calm waters of the anchoring bay. He watched them swim to shore and stream out into the untouched ecosystems of the island. The damage that these rats then did to these tropical paradises is incalculable! And, with reduced numbers of rats left on the ship, the reproductive rate of the remaining colony accelerated and the colony numbers quickly returned to “normal.”

So when we see a brown rat here in Seattle, we are observing an individual whose species has traveled far and wide on the Seven Seas. It has also, in its own way, conquered the world! Be respectful (let’s hope that  they stay out of the toilet!).

Next week: Roof Rats in Seattle! Black rats with their incredibly long tails!

Public Domain

(Click on the following link to listen to an audio version of this blog ….Lets all fall back together

(this is an encore presentation of the time change blog that I wrote in 2024. Enjoy!)

Last weekend we changed back over to Standard Time. This “fall behind” change in our clocks does nothing to alter the total amount of daylight we get in a day but it does change our perceptions of lengths of day and night. Supposedly we get an extra hour’s sleep on that first Sunday morning after the time change, but many of us, I am sure, just got up a bit earlier on clock time than we usually do on a Sunday.

All sorts of studies have explored the impacts of the Fall and Spring time change. The Fall, with its promise of that extra hour of sleep, seems more benign than the Spring change which takes that hour away. One researcher referred to both changes as a type of “jet lag.” Sleep pattern disruptions, headaches, and mood changes were the dominant symptoms, and like jet lag the symptoms go  away within a few days.  The Spring change, though, had some potentially serious consequences: for several days after the “spring back” clock change there is, an increase in work-related injuries, and, possibly (although there are conflicting studies on this) an increase in morning traffic accidents. Interestingly, according to a 2012 study published in the Journal of Applied Psychology, for several days after the Spring time change office workers also increased their on-the-job “cyberloafing” Internet time. Maybe web surfing is an adaptive way to avoid accidents and injuries!

Earth at N. Hemipshere Winter Solstice.NASA. Public Domain

Mornings now are just a little more sunlit than they were before the clock shift and afternoons and evenings are a little less.  We are racing toward the Winter Solstice (December 21 this year) when the North Pole will be tipped as far away from the sun as it goes these days. On the Winter Solstice here in Seattle we will have almost an hour and a half less daylight than we do today (December 21: 8 hours and 21 minutes of daylight, November 5, 9 hours and 44 minutes of daylight).  Do you remember the Summer Solstice back on June 21? We had almost 16 hours of sunlight that day!

Anyway, our shifts from Daylight Savings to Standard times do not affect organisms other than humans, but the on-going transitions of day length and darkness do affect almost every plant and animal species around us.

Photo by D. Sillman

I used to be able to closely watch the impacts of the shortening day lengths and colder temperatures on my late, pet box turtle, Spider. His wonderful, reptilian brain very accurately sensed the length of the light periods in his days and integrated them with the outside temperature.  He would get sleepier and sleepier as the days got shorter and cooler through the Fall. As the season went on, I kept him exclusively in the house, but the decreasing time of sunlight pulled him into a torpor that lasted all winter. In turtles that live in outside environments this seasonally induced dream-state leads all the way into a true hibernation homeostasis. Even keeping him in to the relatively constant temperature of my dining room (where his terrarium was located), he could not resist the physiological changes of the season. He would eat his last nightcrawler of the year sometime in late October and wouldn’t have another until the first or second week in March.

Pezz and Pizo. Phoo by D. Sillman

Our cats, Pezz and Pizo, are incredible hair producing machines! Brushing them or even just petting them in the spring or summer generates great handfuls of shed hair. The shortening day lengths, though, do act to slow down even their amazing hair production and loss rates. In an outside cat the production of hair without the shedding loss would result in a thick, insulating winter coat. Indoor cats usually don’t build up quite as heavy a hair layer but, at least, they slow down their shedding (a little bit, anyway).

Shortening day lengths are the prime stimuli for many of our summer birds to begin their southward migrations. They need to fatten up and leave the area well before food supplies are gone and cold weather has settled in, so getting a pretty benign physiological nudge by the shortening light periods is a great evolutionary advantage.

Photo by zauber. Wikimedia Commons

Even humans respond physiologically to the shortening day lengths, although the pattern of this response is not always the same in all people. Thyroid hormone seems to either go up or get more active in most people in the winter. Logically, it stimulates metabolic rate and heat production especially through the metabolism of carbohydrates and possibly also stimulates metabolic heat generation in the body’s brown fat deposits. Cortisol levels also go up in the winter probably acting to shift metabolism over to using fats (both stored and dietary) for energy. But all of these responses are really quite muted compared to other mammal species that have not developed technologies that protect them from the great stresses of winter.

Plants have all sorts of photoreceptor proteins that respond to day length. These proteins are especially sensitive to the duration of the dark periods. It is the length of the night that drives plant species to flower, or make seed, or senesce. The cessation of chlorophyll production in deciduous tree leaves and its accelerated breakdown reveals the formerly hidden accessory pigments and generates the beautiful color displays of the autumn trees. The red maples were among the first trees to have their leaves turn color and then fall. Oaks and beech trees are among the last to have their leaves turn and may keep their leaves all through the winter.

Where did Daylight Savings Time come from?

Painting by J. Duplessis. Wikimedia Commons

Most histories on the subject start with Benjamin Franklin and his letters to the French authorities in Paris describing the inefficiency of unused daylight in the early morning and the “candle cost” of the early darkness in the late afternoon and early evening. Shifting clocks ahead by an hour, he contended, would more appropriately align the available daylight hours to the activities (and candle usages) of the citizens of Paris.

In World War I Germany shifted its national clocks to extend the daylight period into the evening in an attempt to save energy, and quickly other nations of the world on both sides of the conflict did the same. Retailers in large cities noticed that more people were out walking (and shopping!) on the days with extended afternoon sunlight and lobbied to keep DST after the war. Similar energy arguments were made in World War II and the seasonal return to DST became institutionalized in many national cultures. In fact, the most cogent argument in favor of DST is that it stimulates the consumer economy. Farming interests were quite opposed to the shift to DST and the attempts to portray it as a benefit to farmers are not compelling or logically convincing.

White ashes on Nature Trail (c. 2000) Photo by D. Sillman

In the United States the passage of the Uniform Time Act of 1966 required states to conform to their respective Standard Time zones but allowed them some flexibility with regard to DST. Only Arizona, Hawaii and Puerto Rico, however, have opted not to “spring ahead” into DST each March. There are also several states that have made attempts to make DST a permanent, year-round clock setting although the Uniform Time Act does not allow states the freedom to make these type of changes. It is argued by the permanent DST advocates, though, that shifting daylight minutes and hours into the more highly used afternoon and evening time periods is a better use of sunlight resources. As one DST advocate put it “everyone loves DST!” (a notable exception to this is the “Society for Research on Biological Rhythms” which has petitioned a number of governments around the world to stop the twice-yearly shifting of our social time arrays and stick with the most appropriate time system for our biological systems: Standard Time!

It’s not that Standard Time or Daylight Savings Time is better or worse than the other. It’s the shifting of our time frames twice a year to accommodate the Summer’s Daylight Savings and the Winter’s Standard Times. Anyone with a small child is really going to suffer as bedtime and waking up tines fall into disarray.

In the U. S. Congress a bill called “The Sunshine Protection Act” has been introduced each year since 2018. This bill would establish permanent daylight savings time all across the country. There would be, then, no clock changes in the Fall or Spring. This bill was passed by the Senate in 2022 by unanimous consent with no formal vote taken. The House version of the bill, however, never made it out of committee, and, so, the bill did not become law. It does not appear at this time that The Sunshine Protection Act has enough support to get through congress this year or next year either, so we will continue to be saddled with the twice a year clock changes for quite awhile.

(Click on the following link to listen to an audio version of this blog ….Autumn in Seattle

Sugar maple in the Fall. Photo by J. StJohns, Flickr

Autumn is my favorite season although Spring comes in a very close second. It’s a Goldilocks kind of thing: Summers are too hot and too sticky, Winters are too intensely cold. I like the seasons that are “just right,” and also the ones that are rapidly on their way to becoming something else!

Back in Pennsylvania the first cool nights and the first color changes in the tree leaves were the tip-offs that Fall was right around the corner. There were two, large sugar maples along the main road just across the river from our town that turned a vivid gold long before any of the other trees tipped us off about the changing season. The red maples in my yard slowly turned red, one leaf at a time, it seemed, until each crown was ablaze with color. The leaves then hung on the trees for a couple of weeks, but by Halloween they had fallen and covered the ground and, often, were then covered with a dusting of the season’s first snow.

In Northern Colorado, Fall was a much less obvious season. A local joke said that Fall was the Tuesday in between the Monday-Last-Day-of-Summer and the Wednesday-First -Day-of-Winter. The change was like a switch being thrown. Greeley is a city of planted and tended trees. Their leaves, though, all seemed to change at once and then were sent blowing away almost immediately by the rising winds.

Seattle, Photo by D. Schwen. Wikimedia Commons

Here in Seattle we have been enjoying the long, sunny summer-dry season ever since we moved here in mid-June. We have gotten so used to waking up with light streaming in our east-facing windows that we have forgotten that this is all part of a very finite, four-month climatological gift!

Walking over to my son’s house last week, an older gentleman walking his dog (have I mentioned that EVERYONE here seems to have a dog?) told us “to enjoy the sun while we can” because “the Change is coming fast!”

The Change, is, of course the start of our eight months of clouds and rain.

Seattle’s weather and climate are powerfully influenced by its proximity to the Pacific Ocean.  Air masses rolling in from the Pacific are rich in water vapor and generate a humid environment. The yearly average humidity of Seattle is 70% (with relatively dry months in the summer (60% (May)) and very moist months in the winter (81% (December)).

Rby Beach, Washington. Photo by State Department of Ecology.

The coastal location of Seattle also contributes to its significant (although surprisingly moderate) yearly rainfall (38 inches/year)) Most of this precipitation is spread quite evenly across the eight month “wet” season (from October to May). This is a very important point: in the wet season it rains regularly, but almost never in gully-washing downpours. Our 38 inches of annual rain is spread out over an average of 155 rainy days. That comes down to just over 0.2 inches of rain each day. Seattle rains, then, are mostly drizzles and mists!

Comparing annual rainfall in Seattle to the rainfall in cities located in the Eastern United States, places that do not have wet or dry seasons annually, this very moderate rainfall rate is even more apparent: Boston gets 44 inches of rain a year. New York gets 47 inches. Washington, D.C. gets 42 inches of rain a year, and Houston gets 56. Further inland, Pittsburgh gets 40 inches of rain a year, but, again, not in a wet season/dry season pattern. These rains are isolated events and can be quite intense in their delivery of moisture!

Seattle is known for being cloudy and, especially in the winter, rainy and gloomy. It has, on average 152 sunny days a year and, as I mentioned before, 155 rainy days a year (I am not sure how the other 58 days of the year are classified, but Seattle is said to have 226 cloudy days a year, so some of its “sunny” days must a bit cloudy.

The seasonal oscillation of rain is caused by a fluctuation in air pressures and temperatures in the Pacific. In the summer (our “dry season”) a High Pressure center in the central Pacific pushes relatively dry, cool air toward the west coast. This leads to the sunny, dry days that we have been enjoying ever since we moved to Seattle in June! In the winter (our “wet season”), though, a powerful Low Pressure center forms in the northern Pacific. This “Aleutian Low” pushes a continuous flow of moist air toward the west coast and delivers the eight months of steady rains and drizzles.

Occasionally, air flow across the Pacific can get more energized and focused. These oscillations are called the Madden-Julian Oscillations (MJO’s), and they can deliver very large amounts of warm, moist air to specific locations on the North American West Coast. The MJO’s are sometimes called “atmospheric rivers” (or, because of their approximate point of origin near Hawaii, the “pineapple express”). Rainfall and snowfall amounts at the landfall points for these MJO’s can be considerable!

Olympic Mountains. Photo by Lana. WikimediaCommons

The topography surrounding Seattle also influences this air flow and moisture delivery. To our west is the Olympic Peninsula with its rugged backbone of the Olympic Mountains. Although the Olympics have peaks that are mostly “only” 6000 to 7000 feet high, these mountains rise directly from sea level. They represent, then a significant barrier for the moist, onshore winds. When air is pushed up against a mountain range, it rises and goes up and over that range. As the air rises in the atmosphere, its molecules spread out and begin to slow down causing the temperature of the air to decrease. This is a phenomenon called “adiabatic cooling.”

Cooler air holds less water as water vapor than warmer air, so when an air mass adiabatically cools, it releases some of water vapor as rain (or fog or snow). This is seen quite spectacularly on the western slopes of the Olympics especially in the winter. The moist air being driven to the coast by the Aleutian Low, rises up over the Olympics and drops a huge amount of rain.

The Hoh Rainforest. Photo by M. Gabler. Wikimedia Commons

The “Hoh Rainforest” is a spectacular temperate rainforest located on the coastal side of the Olympic Mountains. The Hoh gets, on average, 142 inches of annual rainfall. Most of this rain is delivered during the “wet season” months (October to May). I have written about the Hoh before (see Signs of Fall 3, September 10, 2015), and I hope to get out there again to see it in average year (2015 was a drought year for the forest and there were hardly any banana slugs on the trails and the epiphytes were all dry as tinder!).

Mount Ranier (over Tacoma). Photo by USGS. Public Domain

The path of air past the Olympics takes it across the Puget Sound and then over Seattle (37 inches of annual rainfall). It then continues on its eastward path until it hits another mountain range. These are the Cascade Mountains (also, on average 5000 to 7000 feet tall with some spectacularly tall volcanoes (I will talk about these volcanoes in another blog!)). The air pushes up the western slope of the Cascades and drops a substantial amount of its moisture. The west slope of the Cascades is wet and lush from this rain. As the air tops the mountains, though and goes back down the other side, the molecules in the air mass are pushed closer and closer together increasing their relative velocities. This causes the temperature of the dropping air to increase. This warming air then sucks moisture from the eastern slope of the Cascades and generates a drier and drier climate.

Spokane, Washington is on the east side of the Cascade Mountains. It is at approximately the same latitude as the Hoh and Seattle, and is, in straight-line distance about 400 miles from the Hoh. The average yearly rainfall in Spokane is 16 inches. Very comparable to Greeley, Colorado! A spectacular change in climate over a very short distance!

On a clear day, from almost any hilltop in Seattle, you can see the Olympic Mountains off to the west and the Cascades off to the east. You can also see the massive volcano of Mount Ranier off to the south. We will watch these mountains turn white with snow (if we get any clear days this winter!). Seattle, though, will stay mostly snow-free, mild and moist throughout the long wet season.

Banana slug. Photo by J. Whitehead. Wikimedia Commons.

(Click on the following link to listen to an audio version of this blog  ….Banana Slugs

The term  “slug” does not have a precise definition in zoology. It is similar in quality and precision to the term “weed” in botany. Slug is a physically descriptive term for the elongated, blobby bodies seen in several groups of gastropods that have given up their shells. Shells are remarkably protective structures, but they are also quite metabolically expensive to make and even more energetically expensive to carry around. The shedding of shells has happened multiple times in gastropod evolution and, so, not all species of slugs are, although they may look similar, very closely related at all.

Slugs look like snails without shells. As I said above, they are species of gastropods in the phylum Mollusca. The term “gastropod” translates into “stomach footed” making note of the muscular locomotory organ on the ventral side of their bodies. Mollusks are the second most diverse phylum of life (behind the Arthropods). There are 76,000 living species of mollusks and possibly over 100,000 extinct species. Mollusks have muscular bodies, complex organ systems and a body-covering flap of tissue called the “mantle” (which makes the shell in the shelled mollusks and other  quite useful structures in other types of mollusks). Mollusks also often have a rough, tongue-like feeding organ called a radula.

The slugs we are interested in for this blog are the large and often (but not always) bright yellow slugs found primarily in the wet forests of North America’s Pacific coast: the banana slug (Ariolimax spp.).   Banana slugs are the second largest, land slug in the world. They can reach lengths of 10 inches and body weights of a quarter of a pound (4 oz.). Only the ash-black slug of Northern Europe (Limax cinereonigo) is regularly larger (it can reach lengths of 12 inches).

Zofia and Ari checking out a banana slug. Photo by M. Hamilton

Banana slugs are found in forest floor vegetational debris in coastal coniferous forests from Santa Clara, California to Southern Alaska.  They also inhabit isolated wet forest microhabitats further inland in California, Oregon, Washington and British Columbia. In these inland forests, the banana slugs are typically found near streams or in other sites that reliably stay moist throughout the year. Banana slugs are extremely sensitive to moisture and will go into an inactive state and roll up into a tight ball well encased by mucus and vegetative materials if their environment begins to dry out. This state of aestivation will persist until drought conditions end.

Banana slugs are detritivores that slowly move through their leaf litter habitats ingesting leaves, mushrooms, animal feces and mosses. Their maximum rate of locomotion is 6 ½ inches per minute! They are able to at least partially digest these ingested materials and then defecate a rich organic mix of humus and some more labile organic compounds. Their feeding and defecating activities  significantly accelerate the decomposition of the forest floor debris and also the rate of nutrient cycling within these ecosystems. Further, banana slugs spread seeds and spores throughout their soil/litter systems.

Banana slugs are Keystone Species in these wet, coastal forests. They set the nutrient cycling tempo and are vital agents in the life cycles of the system’s plants and fungi.

Banana slug. Photo by David, Adobe Stock

The “head” end of a banana slug contains the mouth from which its rasp-like tongue called the “radula” protrudes. The radula is covered with tens of thousands of rough “teeth” that can grind almost any vegetative materials into swallowable paste. Just above the mouth are a pair of relatively large tentacles that can sense light and movement. Just below the mouth are a smaller pair of tentacles that are capable of sensing chemicals and also tactile sensations. The tentacles are retractable and, if damaged, can be re-grown.

On the dorsum (“back”) of the slug is the flap of tissue called the mantel. The mantel is a very useful structure in almost all classes and species of Mollusca. In shelled mollusks, the mantle is the structure that actually makes and supports the shell. In octopuses and squid, the mantle forms the flexible, muscular sack that encases and protects the internal organs. In banana slugs, the mantel sits on the back like a saddle blanket guarding and protecting the single opening to the slug’s lung (an opening called the “pneumostome”). In addition to respiratory gas exchange in the lung, the moist skin of the slug can allow diffusion of both oxygen and carbon dioxide between the slug’s body fluids and its environment.

Banana slugs are often bright yellow, and some of the eight species also have distinctive dark spots on their bodies.  Banana slugs, though, can also be gray in color or even black. These colors may reflect the age and health of the slug, or they may just be random expressions of the range of appearance of the different species.

Banana slugs on a hand. Photo by R. Averson. Wikimedia Commons

The mucus produced by a banana slug is one of its most compelling features. This mucus is neither a liquid or a solid but, instead, is classified as a fluid crystal. Banana slug mucus is able to absorb 100X its weight in water and primarily functions to keep the slug from drying out. The mucus also provides lubrication for the delicate body of the slug as it crawls over rough materials and surfaces. The mucus is also rich in chemicals that include pheromones (to attract other banana slugs) and also for protection. These protective chemicals can irritate and even numb the mouths of a potential predator (or the fingers of a human handling the slug). Their bright colors are thought to be warning signs to predators advertising the consequences of trying to disturb or eat a slug.

Many predators, though, do eat banana slugs. Small to medium sized mammals, birds, snakes and salamanders all have been observed consuming them.   Sometimes, the slug is well thrashed in loose soil before ingestion, though, in order to remove the noxious mucus.

Two banana slugs about to mate. Photo by Andy,gotyachev. Wikimedia Commons

Banana slugs are hermaphroditic (meaning each individual has both male and also female reproductive organs. Banana slugs can self-fertilize, thus producing clones of the parent slug. They can also copulate with another slug and exchange packets of sperm producing a genetically diverse set of offspring. Sperm is exchanged via a penis-like structure which the slug gnaws off in order to break away from its copulatory partner (don’t worry, it grows back!). A fertilized slug lays between 3 and 50 eggs in protected crevices within the leaf litter.

Humans also can eat banana slugs, although the experience has been described as quite unpleasant. There are yearly banana slug festivals where banana slug dishes are available and also banana slug races are held.

The banana slug is the official state slug of the State of California. It is also the mascot of the University of California at Santa Clara. In 2004, the magazine Reader’s Digest named the UC-Santa Clara banana slug the best college mascot in the United States!

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(Click on the following link to listen to an audio verison of this blog …Modern Breads

I have written about bread in two previous blogs (“Delicious Microbial Systems,” February 2, 2017, and “Ecology of Sourdough” February 29, 2024). Bread making is a craft that was first developed in Neolithic Asia some 14,000 years ago. The leavening agents used in breads (i.e. the things that make the bread rise) were originally and until relatively recently, natural, microbial systems. The ecological interactions among the microbial species accomplishing the leavening are fascinating! Complex ecosystems living in tiny jars and bowls! Today, most breads are made with specialized bread yeasts. Those breads that still rely on natural, microbial systems for leavening are often referred to as “sourdough” breads.

To make bread, you only need four ingredients (flour, water, salt and a  leavening agent). You also need a considerable amount of time.  Modern, commercially produced breads have developed all sorts of shortcuts and have added all sorts of ingredients to their bread recipes to cut the bread making time down to as brief a period as possible! As they say, “time is money,” and our new breads must be made as inexpensively as possible!

There was an article in the NYTimes this summer (July 24, 2025) that noted that many people who have digestive problems (including bloating, nausea, diarrhea and constipation) and even systemic problems (fatigue, joint pain and brain fog) when they eat bread made in the United States often see those problems disappear when they eat bread that is made in Europe. Let’s explore some possible explanations for this observation.

1. Nature of the flour used to make the bread.

Wheat is an annual grass that makes very large seeds (“grains”). These seeds can be directly consumed or ground into flour. The earliest wild wheat was from Western Asia. They were “harvested’ on a small scale and consumed by hunter-gatherer peoples some 23,000 years ago. Domesticated wheat was derived from wild wheat plants. The domesticated forms of wheat produced even larger seeds and very uniformly tall, hardy stems. This domesticated wheat was first grown in the Fertile Cresent about 10,000 years ago.

Most of the wheat grown today (95%) is a single species (Triticum aestivum). Wheat fields worldwide cover 545 million acres. That is an area greater than that occupied by any other food crop, and the total world trade in wheat is greater than the tonnage of all other food crops combined!

Although most wheat grown are all the same species, there are many varieties of that species that are best adapted to particular soil and climate conditions. These different varieties also generate quite different types of flours!

“Hard wheats” are grown in locations with abundant moisture, lots of soil nitrogen and a wide range of seasonal temperature fluctuations. Hard wheats have high protein and gluten levels and make flours that use this gluten to generate very solid bread shapes and structures. Most of the wheat grown in North America (especially in the High Plains and across Canada) are hard wheats.

“Soft wheats” are grown in humid locations that experience moderate seasonal temperature fluctuations. These soft wheats have relatively low protein and gluten compositions. Wheat grown in the Midwest of the United States and in much of Europe are soft wheats.

The geography of wheat production influences the flours that are available to bakers. Most North American bakers utilize flour made from the locally grown hard wheats. This flour and the resultant breads, then, are high in protein and gluten. Most European bakers utilize flours from their locally grown soft wheats. This flour and the resultant breads, then, are low in protein and gluten.

Gluten sensitivity and reactivity, then, may be a factor in the increased “digestibility” of the generally lower gluten European breads.

2. Bread doughs are fermented longer in Europe than North America.

During fermentation, carbon dioxide gas is generated which acts as the leavening agent causing the bread to rise. Both types of leavening system (either bread yeast or the complex microbial systems of yeast, fungi and bacteria in a sourdough starter) break down the simple sugars, some of the polysaccharides and even some of the proteins and the glutens in the dough in order to generate the carbon dioxide.

In Europe, typical fermentation (“rising”) times for commercial breads are 12 to 48 hours. In North America, the typical fermentation (“rising”) time for commercial breads is a fraction of this often as little as one to two hours. Time, after all, is money!

During the longer fermentation periods a particular class of polysaccharides can be broken down. These are the “fermentable oligosaccharides, disaccharides, monosaccharides and polyols” (or “FODMAP’s”). FODMAP’s in breads are not digested in the small intestine but instead pass through the upper GI tract and enter the large intestine intact. In the large intestine, the colonic bacteria begin to wildly proliferate and rapidly break down the FODMAP’s. The consequence of this colonic fermentation of the FODMAP’s is similar to that in someone with lactose intolerance who eats a lactose-rich dairy product: colic and cramps, gas production, flatulence and diarrhea.

The European fermentation (“rise”) times and any true sourdough leavening system with its long fermentation time should involve a sufficient amount of time to at least begin to break down the FODMAP’s in the bread dough. The very short fermentation times in North American commercial breads, though, is not at all sufficient to reduce the FODMAP load in the bread,

Higher levels of FODMAP’s in North American-made breads, then, might also be a contributing factor to its increased involvement in bread-intolerance reactions.

What about sourdough bread made in North America? Many North American sourdough breads that are sold commercially are, like the regular, yeast-risen breads, rushed through their fermentation stages. The levels of FODMAP’s, then, in these “fake” sourdoughs are not reduced. Looking at the ingredient label of a commercial sourdough bread can give you a hint as to whether it is a “real” sourdough or not. Inclusion of lactic acid or vinegar (which give the bread a “sour” or “tart” taste) is a good indication that the bread was not fermented long enough to be a real sourdough and have reduced levels of FODMAP’s.

3. Breads made in Europe have fewer additives.

As I said in the introduction to this blog, bread only requires four ingredients: flour, water, salt and a leavening agent. The long list of ‘other” ingredients that are listed in the multiple lines of ingredients (especially in breads made in North America) are used in the bread making process to accomplish one of two tasks. They either make the bread rise and form a more acceptable density and crumb structure in a very rapid time frame (a natural fermentation time, as we mentioned above, can be quite long, and commercial bakeries attempt to shorten this as severely as possible to save money). Or these additives may increase the shelf-life of the bread by preventing mold formation and loss of moisture (“going stale”). These shelf-life impacts also extend and increase the economic value of the bread.

Bread label. Figure by Vargas and Simsak

Additives that act to accelerate the development of crumb structure and loaf-loft include emulsifiers like lecithin, and mono- and diglycerides and calcium stearoyl lactylate. These aditives improve the dough texture and stability. Ascorbic acid (vitamin C) is also added to improve loaf volume and crumb structure, and vital wheat gluten may be added to the bread dough to strengthen the gluten network throughout the bread. Soya flour may also be added to make the dough-system lighter and reduce the rising (fermentation) time of the dough.

Additives that increase the shelf life of a loaf of bread include calcium propionate and potassium sorbate which inhibit the growth of mold. Enzymes like amylase are added to bread to keep the bread moister longer (i.e. inhibits staling). High fructose corn syrup, sucrose and honey which sweeten the bread and also bind moisture in the loaves, and fats like palm oil make a softer and moister crumb structure, Also a number of antioxidants like BHT (“butylated hydroxytoluene’) and BHA (”butylated hydroxy anisole) may be added to keep breads from getting stale. Both BHT and BHA, by the way, have been implicated as potential causes of human disease!

The abundance of chemical additives in North American breads, then, may have both long-term and short-term impacts on human health!

4. Breads made in Europe are unlikely to contain glyphosate residues.

Photo by Monsanto Consumer. Flickr

Glyphosate is a commercial herbicide also known as “Round Up.” Many crops are grown in agricultural systems in which glyphosate is used for weed control. Monocot crops (like wheat, oats, barely, rice, sorghum and corn (“maize”)) are unaffected by glyphosate, and, so, glyphosate is widely used in these crops to kill weeds. Certain dicot crops (like soybeans) have been genetically modified to be unaffected by glyphosate, and, so, “round-up ready” soybeans are grown extensively around  the world. In the United States farmers are allowed to apply glyphosate to wheat until just before harvest. Late applications of the herbicide are quite effective in eliminating late season weeds and also helps to accelerate the drying of the wheat seeds. This late application, though, leaves a residue of glyphosate on the harvested wheat!

In Europe, glyphosate cannot be sprayed in wheat any time close to harvest.

Most experts agree that the levels of these glyphosate residues in bread are vanishingly small. Glyphosate, though, is implicated in human liver disease, reproductive organ and cell disruption and neurological disorders. It is also listed as a carcinogen and a possible cause of non-Hodgkin lymphoma.

5. Vacation Effect

Champs Elysees Paris. Photo by J. Hammett. Wikimedia Commons

Stress can affect the organ systems of the body in many, negative ways. The digestive system and its ability to efficiently breakdown and absorb food is, in particular, quite sensitive to the effects of stress. Many of the symptoms listed by people eating American made breads can be explained in terms of the impacts of stress. Not experiencing these symptoms when one is on vacation, say, in Europe, may be because your stress levels are reduced. Exercise is also an excellent way to reduce stress, and many people on vacation are more physically active and, especially, are walking more.

So, the phenomenon of greater digestibility of European-made breads over North American-made breads may be due to the nature of flour, the timing of the fermentation, the use of added chemicals of, even, herbicide residues. It also might also be a consequence of stress.

Anybody want some bagels or a pizza?

American crow. Public domain

(Click on the following link to listen to an audio version of this blog ….Seattle Crows Part 2

The American crow (Corvus brachyrhynchos) is a loud and obvious avian species that inhabits a variety of habitats all across North America. It is a large bird (17 to 21 inches long with a wing span up to three feet). It has a chunky body and shiny, black feathers. It also has a variety of interbreeding sub-species.

Crows are seldom seen alone. During the breeding season (spring to late summer) American crows form small, cohesive, familial flocks, that break up into even smaller foraging groups that daily travel out across the countryside looking for food. The multigenerational make-up of these flocks and foraging groups undoubtedly adds to the success and survival of each year’s nestlings and fledglings. Some “selfish gene” concepts of Richard Dawkins and W. D. Hamilton undoubtably are at work here!

In the non-breeding part of the year (fall through the winter) American crows form large, communal flocks of hundreds to thousands of individuals. These large, winter flocks are often found in urban areas (much to the distress of the area’s human residents!).  The crow flocks in Bothel, Washington (mentioned in the previous blog) is an example of one of these communal, winter gatherings. Another, well studied winter flock is in Lancaster, PA. This flock is even larger than the Bothel flock numbering 20,000 individuals! The warmth and lights of the city environment and the protection it brings from great horned owls and other crow predators are thought to be some of the factors that are selecting for these urban-centered crows.

American crow and fledgling. Photo by I. Taylar. Wikimedia Commons

Communication between individuals in the foraging groups and within the larger flocks is a very important aspect of crow biology. The remarkable and extensively documented intelligence of crows (their ability to solve food-gathering problems, to learn to mimic human vocalizations, to employ a variety of complex strategies to gather food etc.) is thought to be a direct extension of their evolutionary success as a social, highly efficiently communicating species. Crows, by the way, have longer rearing and nurturing periods than other birds. These “learning periods” are even longer than those observed in many mammals. These nurturing periods can last up to a year and a half and enable the parental generation to communicate extensive amounts of very functional survival information (hunting and foraging strategies and techniques, habitat selection preferences, etc.) to their offspring.

American crows can be found residing in or moving through a great variety of ecological habitats. They seem to prefer a broad functional range that includes both fields (for grasses and seeds and for small vertebrate and invertebrate prey species) and woodlands (for night roosts and for protection). Human agricultural systems are especially favored by the American crow. Their negative impacts on grain crops etc. can be extensive. It is estimated that in the United States the summed American crow population numbers over three billion individuals! Many states allow hunting of crows to try to control their numbers. Recently, however, the impact of West Nile Virus (to which American crows are extremely susceptible) has significantly reduced their population numbers.

American crows. Photo by D. Sillman

Crows eat a great variety of foods from grains to fruit to invertebrates (like grasshoppers, grubs, earthworms, caterpillars, etc.) as they become seasonally abundant. Vertebrates (bird eggs, small birds, rodents) are eaten opportunistically or may even be actively hunted. Some years ago at my home in Pennsylvania, I observed a crow swooping down on a low flying female northern cardinal. The crow slammed down on the cardinal striking it with its chest and knocking it to the ground. The crow then landed next to the dazed, but still moving cardinal, picked it up in its beak, and flew off with it. Several other crows followed close behind, and the whole group was loudly pursued by five or six blue jays. I have in the past observed crows picking off young red squirrels as they walked in line along a tree branch, and I have read about some crows actively hunting small birds

Crows also consume carrion and are active scavengers of human garbage (as I mentioned last blog concerning the neighborhood crows of Olympic Hills, Washington!). Crows utilize their excellent vision to find and obtain their food. While hunting and feeding, individuals of the flock take specialized jobs (some functioning lookouts, for example, while others of the flock feed). Vocal communications between individuals of the flocks are critical to the overall success of the foraging group. Complex hunting behaviors have also been observed in crows. Some these include mobs of crows driving rabbits from a field across a roadway. A percentage of the driven rabbits were hit by cars and were then consumed by the crows. Crows have also been observed actively interfering with other predators (like river otters) to distract them from their captured prey which the crows then appropriate for their own consumption. These behaviors are further examples of the group dynamics and extreme intelligence of this remarkable species.

Northwestern crow. Photo by G. Leggett. Wikimedia Commons

The Northwest crow is now considered to be a variant or sub-species of the American Crow. DNA analysis of individuals identified as “Northwest crows” indicated massive hybridization with American crows (in fact, there were no “pure” Northwestern crow individuals collected!). Exploring the “Northwest crow” DNA patterns indicates that there was a distinct break separating “Northwestern” individuals from “American” individuals. This break occurred 440,000 years ago right at the start of “ice Age” glaciation cycles. Ice sheets, then separated a formerly contiguous population of crows into a coastal subgroup and a continental subgroup.

This separation lasted long enough for certain phenotypic differences between the coastal crows and the continental crows to develop. The coastal crows became smaller (due to differences in food supply or, possibly, due to the warmer more stable temperature conditions of the coast (Bergman’s Rule states that animals in colder climates will be larger than their counterparts in warmer climates). Some have also suggested that there is less predation pressure on costal crows so that development of larger body sizes that might discourage predator attacks was not advantageous.). Vocalizations, so vital to these intensely communicating birds,  also diverged. Birds scavenging in the complex habitats of the coast may also have developed more aggressive personalities and more intense expressions of their innate curiosity as part of their nearly constant search for food.

The time frame of this separation, though, was insufficient to sustain the landscape reproductive barriers. Once the ice sheets melted, the coastal and the continental crows once again intermixed and interbred.

Fish crow. Photo by Rhododendrites. Wikimedia Commons

On the East Coast of North America there is a similar coastal and continental crow split. The continental crow is the American crow while the coastal crow is the fish crow (Corvus ossifragus). This fish crow/American crow East Coast dichotomy may have been the driving reason behind the assumption that the Northwestern crow and the American crow were distinct species. The fish crow, like the hypothesized Northwestern crow, is smaller than the American crow and more slender, it also has a more slender bill and narrower feet. Its call is quite different from the American crow (often described as a nasal “uh uh”). Fish crows are found in the coastal wetland and marshes of the southeast coast and feed almost entirely from these wetland ecosystems.

Fish crows, though, do not readily interbreed with the American crow. They are, unlike the Northwest crow and the American crow,  distinct species. Why?

Jamaican Crow. Photo by R. Knight, Wikimedia Commons

Fish crows are closely related to crow species of the Caribbean (like the palm crow (C. palmara) of Hispaniola and the  Jamaican crow (C. jamaicensis). These Caribbean crows split from their last common ancestor of the American crow about 13.5 million years ago. That was more than enough time for reproductive barriers to becomes established between the species.

Fish crows, like American crows, form small foraging flocks and sub-groups which then merge into large, overwintering flocks. Unlike the American crow, though, fish crows do not form these flocks with their close relatives. Instead a fish Crow flock is usually a gathering of similarly aged individuals. One fish crow researcher commenting on this indicated that he wasn’t sure if the adult fish crows kicked the juveniles out of the family unit or if the juveniles left the adults on their own. Either way, fish crows lose some evolutionary advantages by not have shared-DNA individuals caring for each other, but possibly they gain some benefit by reducing the possibility of in-breeding.

Recent observations on the distrubution of fish crows indicates that they are spreading out from their coastal habitats. In particular, they are increasingly found along the large rivers that drain into the Atlantic Ocean and Gulf of Mexico. These riparian habitats had been occupied by American crows, but the impact of West Nile Virus, as I mentioned before, has reduced the population of American crows and provided an ecological opening for the West Nile resistant fish crow.

Crows have always been one of my favorite birds! I deeply appreciate their intelligence and their ability to work in coordinated  ways for group-beneficial ends. People could learn some things from crows!

American crow (in Pennsylvania) Photo by D. Sillman

(Click on the folloiwng link to listen to an audio version of this blog …Seattle crows Part 1

Going for a walk on any of the narrow streets of the Olympic Hills section of Lake City, Washington, you almost always gather up a trailing entourage of noisy, curious, and focused critters: the neighborhood crows! Groups of crows numbering between 3 and 8 individuals bounce between overhead utility lines and surrounding tree and shrub branches as they shadow along waiting for you, the nimble human in front of them, to conjure up some food. These neighborhood crows seemed to be more “in-your-face” than the more aloof crows of Colorado and Pennsylvania. They seem interested in pulling off a quick shakedown and not in developing some long-term symbiosis.

Often the crows already have food in their beaks especially if it’s garbage day (Fridays in the Olympic Hills). One time one of the crows following me was carrying an entire English muffin! I don’t see how he could have expected to improve on that!

Crow with food. Photo by V. Musilenko, Wikimedia Commons

Many of the other crows carry sticky looking wrappers and, sometimes, greasy looking bones or unidentifiable old pieces of food. Joe and Marlee have seen crows drop chicken bones into their back yard. Are they trying to feed Joe and Marlee’s dog, Ozzie? Is this some sort of religious sacrifice to a large, black, god-like dog? Is it some sort of peace offering, or are they trying to kill him? Anything seems possible.

There has been a great deal of research examining the intelligence of crows. Some of these studies have also explored the ability of crows to communicate and to remember traumatic events. Other studies have looked the ability of crows to solve problems or use tools (usually to get food!).

Flock of crows. Public Domain

In Bothell, Washington just north and east of here, 16,000 crows regularly gather in a winter flock on the campus of the University of Washington-Bothell. This winter roosting started in 2009 possibly because the campus’ trees had grown sufficiently tall to provide protective night roosts for the crows and also because a restored wetland on campus helped to make the area safe and secure for the birds. The wetland also generated a potential habitat for food. Gatherings like this are thought to provide the crows with opportunities to share foraging and landscape information. It’s also a chance to meet a non-related, potential mate (see Signs of Winter 5, January 20, 2022)

John Marzluff at the University of Washington in Seattle clearly showed that crows not only remember trauma and disturbance, but also can communicate the details of these events to their flock-mates. Back in the 1990’s,  Marzluff and his banding team wearing “caveman” masks caught and banded (and then released) a cohort of crows. Subsequently, Marzluff and his team returned to the crow banding area and were ignored unless they wore their caveman masks. Not only did the crows that had been directly captured and handled by the “caveman” scientists remember and react to the masks, but also their fellow flock members quickly learned the caveman face and joined in on the mobbing and commotion. Over the past thirty years Marluff and his team have regularly returned to this crow territory and though the originally trapped crows are now undoubtedly all dead and gone, the flock still responds in what the article describing the study calls a “crow-pocalyspe” whenever the caveman-masked researchers return.

American crow on flence. Photo by H. Paul. Flickr

These studies (along with some remarkable brain activity analyses using PET scanners and radioactive isotopes) not only show individual crows to be extremely intelligent (Mazluff calls them “flying monkeys!”) but also highly connected within their flocks to a communication and information system that has to be defined as culture!

One afternoon, shortly after we all moved to Seattle, I was sitting in my son’s backyard. Crow after crow flew over to see if I had anything edible to offer. I noticed, though, that the calling of these crows was different from the calls of the crows iI had known back in Colorado or Pennsylvania. The calls seemed more raspy and lower pitched, like the birds were clearing their throats! The Colorado and Pennsylvania crows had sharp, slappingly-loud caws. This realization stimulated me to look at the crows more closely: the Seattle crows didn’t look exactly like my Colorado or Pennsylvania crows: they were smaller and more slender. As I mentioned before, they behaved differently, too. They seemed more aggressively curious and much less concerned with human actions or boundaries.  Were these crows American crows (Corvus brachyrhynchos) or were they something else?

Northwestern crow. Photo by G. Leggett. Wikimedia Commons

I turned to my standard reference (thank goodness it was unpacked from our moving boxes and ready to read!) to see if it had any information about these “Seattle” crows: I paged through my well-thumbed copy of Peterson Field Guide to Birds of Western North America (5^th Ed.)(2020), and on page 278 came across a description of the “Northwestern crow (Corvus caurinus).” Peterson describes the Northwestern crow as a slightly smaller version (16 inches long) of the American crow (17 to 21 inches long). It is found exclusively on the narrow coastal strip (beaches, marshlands, and sounds) of northwestern North America. It is listed as “rare.” Was I seeing this rare species here in our neighborhood of Lake City Washington?

The brief description in the field guide also suggested that the Northwestern crow might not really be a unique species. It may just be a coastal variant of the American crow.

So I went to the Internet and found lots of articles about crows in Seattle and lots of discussions about the Northwestern crow.  Consensus: no one could really ID a Northwestern crow in the field (identifications seemed to be made based on location of the observer more than anything else. If you were on the coast, the crow must be a Northwestern crow). The Northwestern crow interbreeds extensively with the American crow. Most coastal crows were well-mixed hybrids. Finally, in 2020, The American Ornithological Society announced that it was removing Corvus courinus from its species list. The Northwest crow was now, officially, a type of American crow.

Northwestern crow. Photo by D. Daniels. Wikimedia Commons

So I wasn’t seeing a rare, coastal crow species gathering spilled garbage in my new Seattle neighborhood. But these crows were different from the larger, louder more aloof crows I have observed over the years in Pennsylvania and Colorado. Why were they smaller? Why did they “caw” differently? Why were they so active and into everything?

Crows are in the taxonomic family Corvidae. The earliest fossils of corvid species have been found in Europe and have been dated back to 17 million years ago. It is thought that the corvids originated in Southeast Asia and then quickly spread out across the globe diversifying rapidly. Their ability to live a wide range of environmental conditions and to consume a wide range of foods and their remarkably high levels of intelligence enabled them to colonize and adapt to habitats in almost every non-polar climate zone on the Earth. Currently there are 139 species in Corvidae (which includes jays, ravens, rooks, magpies, nutcrackers, crows and more). Crows are in the genus Corvus, and Corvus has 50 of these 139 Corvidae species. Crows, then embody the diversity and potential of this important group of birds.

(Next blog: more about coastal and continental crows!)

Rufous hummingbird. PublicDomain.

(Click on the following link to listen to an audio version of this blog … Seattle Hummingbirds Part 2

The Rufous Hummingbird is more slender and shorter than the Anna’s. It is between 2.8 and 3.5 inches long with a wingspan of 4.3 inches. It weighs between 0.1 and 0.2 ounces. The male is a bright orange on its back and belly (it looks “like a glowing coal ember”) and has an iridescent red throat. The female has a green back with hints of rufous on its sides and spots of rufous on its tail. Females also have an orange spot on their throats.

Rufous Hummingbirds nest in open or shrubby habitats and are especially fond of forest edges or the periphery of forest clearings. They hang their cup-shaped nests in many different locations including on the terminal branches of coniferous trees and from the exposed root masses of wind-thrown trees. The nests are made up primarily of plant fibers and moss bound together with gathered spider silk and are often covered with camouflaging lichens, bark and leaf fragments

Rufous hummingbird. Photo by R. Leche. Flickr

Rufous hummingbirds frequently reuse and/or rebuild old nests. They seem to have a good sense of ‘place” for their nests and return to a specific location several years in a row. They also, according to the Texas Breeding Bird Atlas, nest in groups that are sometimes as large as 20 or more pairs.

The Calliope Hummingbird like the Rufous migrates north in the summer. They generally following the mountain ranges of the Cascades and then loop back south flying near the Rockies to return to Mexico for the winter. Calliope Hummingbirds are the smallest bird in the United States! The male has stunning magenta-colored rays on his throat.

Calipoe hummingbird (male). Photo by B. Pancamo. Wikimedia Commons

The Calliope has an extensive breeding range that extends all across the western United States and Canada. The Calliope nests mostly at high altitudes in the Rocky Mountains from southern British Columbia and Alberta down to Colorado. It also breeds and nests in southern California. Nests are built in a variety of habitats including willow and alder thickets, mountain meadows and open coniferous forests.

The Calliope Hummingbird is distinctly smaller than the other hummingbird species. It is between 3.1 and 3.5 inches long but barely reaches 0.1 ounces in weight. It has a wingspan of 4.1 to 4.3 inches. The Calliope when it perches assumes a “hunched” posture (which makes it look even smaller than it is). Both male and female Calliopes are green on their backs and white on their chests and bellies. The male has, as I mentioned before, magenta streaks of feathers on his throat.

Calliope hummingbird (female). Photo by V J Anderson. Wikimedia Commons

The Calliope migrates in the fall  to the Southwestern United States, Mexico and even down into Central America. It is the smallest long-distance migrating bird in the world covering distances of up to 5600 miles twice a year.

Adult male Calliopes return to their breeding ranges weeks before the females. From the middle of April to early May, the males claim and defend prime mating territories in anticipation of the arrival of the females. A male will breed with as many females as possible and then leave the females to make the nest, incubate the eggs and raise the nestlings. Often the males actually leave the breeding area by the time the nestlings hatch. This behavior reduces competition for local nectar and insects and may result in increased vigor and survival of the nestlings

Female Calliope hummingbirds feedingtwo nestlinga at her nest. Photo by W. Wander. Wikimedia Commons

The Calliope nest is an open cup typically hung under a protective tree or shrub branch. Sometimes the nest is attached to the base of a large pine cone and is modeled to look like a pine cone itself. Nests may be used for several years. Two eggs are laid from late May to early July, and they hatch after a 15 to 16 day incubation. The nestlings fledge after another 20 days.

Female and fledgling Calliope Hummingbirds leave their nesting grounds almost immediately. They disperse into regions rich in late summer wildflowers and scatter themselves across the western mountains.

Male Black-Chinned Humingbird. Photo by Mdf. Wikimedia Commons

The Black-Chinned Hummingbird actually has a dark purple band below its black throat, but the light has to hit it just right to see its true color. Under most conditions, this throat band also looks black and just adds to the common name of this bird. The Black-Chinned Hummingbird is 3.5 inches long with a 4.3 inch wingspan. They weigh between 0.1 and 0.2 ounces. Both males and females are a dull, metallic green on their backs with a dull gray-white coloration on their bellies. They also have some metallic green feathers on their sides. The males, as we have previously mentioned, exhibit the eponymous “black” throat and chin.

Like the Rufous and Calliope the Black-Chinned Hummingbird is a migratory species. It can be found in a broad range of habitats across southwestern Canada and the western United States (from Alberta and British Columbia east to Oklahoma and south to Mexico).  We used to see Black-Chinned Hummingbirds at our backyard nectar feeder in Greeley!  They seldom come through Seattle but instead tend to stay both to the south and east of the Washington coast.

Female Black-Chined Hummingbird. Photo by Mdf. Wikimedia Commons

Black-Chinned Hummingbirds can be found in mountains, woodlands, orchards, meadows, and chaparral habitats. They most often breed in open, semiarid areas, usually near water. They can breed all across their North American range even as far south as Mexico. They especially favor moist environments like orchards, shaded canyons, and riparian woods. Males and females select different habitats before and after breeding possibly, like the Calliope Hummingbirds, to reduce intra-specific competition and make food resources more available for nestlings.

Nests are built entirely by the females and are densely constructed, cup-shaped structures made of plant fibers, spider silk, feathers and lichens. Nests are located 6 to 12 feet from the ground often on relatively exposed, horizontal tree branches just below the dense cover of the tree canopy.  Interestingly, these nests are often located near an active nest of a hawk! It is thought that the Black-Chinned Hummingbird is too small to be potential prey for a hawk, but that the presence of one of these larger raptors is an effective deterrent against smaller, avian predators (like jays and crows) that might prey on the hummingbird’s eggs and nestlings (or the hummingbirds themselves)!

Black-Chinned Hummingbirds are known to hybridize with a variety of other hummingbird species. Ten different hummingbird species from six different genera (including Anna’s, Lucifer, Broad-Tailed and Costa’s Hummingbirds) are known to breed with Black-Chinned Hummingbirds when their respective breeding grounds overlap. The subtle mix of characteristics and features can make identification of these hybrids difficult!

(Next two blogs are about Seattle’s crows!)

Anna’s humingbird (male). Photo by Ella May 81. Wikimedia Commons

(Click on the folloing link to listen to an audio version of this blog …. Seattle Hummingbirds Part 1

Most birding guides list four hummingbird species that live in the Seattle area: Anna’s Hummingbird (Calypte anna), the Rufous Hummingbird (Selasphorus rufus)), the Calliope Hummingbird (Selasphorus calliope)and the Black-chinned Hummingbird (Archilochus alexandri). Of these four species, though, only Anna’s and the Rufous Hummingbirds are regular visitors. The Calliope and the Black-chinned Hummingbirds are more likely to be seen east of the cascades and out further into eastern Washington and only very rarely visit Seattle.

The true hummingbird star of Seattle parks and backyards is Anna’s Hummingbird. They are year-round residents of this very high latitude location and often stake out a specific territory (usually associated with a well maintained nectar feeder!) for all of the summer, fall, winter and spring months of the year.

Hummingbirds are all small, but Anna’s occupies that large end of this “small” continuum. They are up to 3.5 inches long with wingspans of 4.7 inches. They only weigh 0.1 to 0.2 ounces, but have a solid, stocky body that makes them appear more substantial. They have broad tails that extend past their wingtips when they perch, and both males and females are covered with gray and green feathers. The males also have a very distinctively colored head that is covered with iridescent reddish-pink feathers.

Anna’s humingbird (female). Photo by M. Field. Wikimedia Commons

Anna’s Hummingbird’s original territory, as I have talked about before, (Signs of Winter 10, February 7, 2019) was the relatively small area of extreme southern California and the northern-most parts of Baja California. In this compact range the birds consumed a wide variety of types of insects and arachnids and drank nectar from a diverse group of flowering plants. They also drank tree sap (especially from trees whose bark had been fractured by feeding woodpeckers or sapsuckers) and readily ate any insects that might have gotten caught in the sticky secretions. They were by necessity extreme generalists with regard to their dietary preferences because no one plant or insect was present in sufficient abundance to support their entire population, and, for

Eucalyptis tree. Public Domain.

similar reasons, they were not terribly picky about where they built their nests. The desert to the east and the dry chaparral to the north very effectively restricted their dispersion out from their original range. Humans, though, eventually changed the vegetational map of the west coast and southwest deserts and freed Anna’s Hummingbird from its ecological confinement.

As people moved into California they planted more and more nectar producing, often exotic, plant species in their yards, parks and gardens. They also planted large numbers of exotic trees which were sources not only of insects but also nectar and tree sap. One type of tree around which large numbers of Anna’s Hummingbird are regularly found is the eucalyptus, and eucalyptus trees were extensively planted in California starting in the mid-1800’s.  By the early 1900’s, Anna’s Hummingbird began to spread out from its restricted habitat range. Its ability to consume so many different types of plant nectars and saps and insects and its broad tolerance of nesting sites allowed it to establish itself in almost any human modified habitat that it encountered.

Anna’s humingbird (male). Photo by USFWS. Public Domain

Anna’s Hummingbird spread north up the coast of California and now is found in abundance all the way up to Vancouver, Canada (with occasional birds found even further north all the way up into Alaska!). To get an historical time perspective on the rate of this spread, Anna’s was first recorded in the Puget Sound area around Seattle in 1964. Anna’s eastward movement through the desert (from one human manufactured oasis to the next) now stretches across Arizona and New Mexico into the western-most reaches of Texas and up into southern Nevada and Utah. Because of their ability to utilize human constructed, exotic species dominated plant communities of yards and parks, there are many more Anna’s hummingbirds today than there were prior to European colonization of the west coast! Anna’s Hummingbird is truly the backyard hummingbird for the entire West Coast!

One interesting behavior exhibited by male Anna’s Hummingbird is called “looping.” The intent of this rapid and repetitive movement is probably to assert ownership of section of a garden or yard and also to impress a potential mate. When looping, the Anna’s Hummingbird hovers in place near the ground and then slowly rises up to about 50 feet of height. They then dive back down at top speed generating a loud “chirp.” The chirp comes from air vibrating the edges of the rigidly held  tail feather like a reed vibrating in a woodwind orchestra instrument. The males then return to their starting spots and repeat the action over and over.

Anna’s hummingbird (male). Photo by Norvig. Wikimedia Commons

Hummingbirds are able to over-winter in Seattle  and the surrounding Pacific Northwest in spite of its high latitude because the area is kept relatively warm all winter by the proximity of the Pacific Ocean. There are some days, though, and many nights when temperatures drop below freezing and when snow may actually fall on coastal locations. Anna’s hummingbird is able to tolerate these extreme conditions by utilizing two physiological adaptations: 1. It can quickly convert the sucrose that consumes during the day into fat (which then serves as both a body insulator and also an efficient metabolic fuel for the long, cold night), and 2. It can go into a low metabolic rate torpor at night to conserve energy.

Humans can reduce the metabolic stress on Anna’s hummingbird by planting winter blooming plants in their yards (plants like winter jasmine, winter blooming grapes or witch hazel), or by maintaining outside nectar feeders throughout the winter. Keeping the nectar bottle from freezing is vital and the Seattle Audubon Society recommends using either plumber’s heat tape, a hanging, shop “trouble” light, or even a coiled up mass of outdoor Christmas lights to keep the nectar above freezing. Duct taping a hand-warmer packet to the side of the feeders is also a good short-term heat fix against nectar freezing! Taking the feeders in each evening is also a possibility, but you have to remember that hummingbirds get up VERY early in the morning!  The Seattle Audubon also stresses that the nectar should only be made with cane sugar (sucrose) and only be mixed in a one part sugar to four parts water ratio. Higher sugar concentrations may actually make it hard for the hummingbird to suck the sugar water up across their tongues and may even do damage to the bird’s kidneys and liver.

Rufous hummingbird. PublicDomain.

The Rufous Hummingbird, the other frequently seen Seattle hummingbird, is almost always actively migrating. They overwinter in southern Mexico and breed in Alaska, British Columbia and to a lesser degree down the Pacific Northwest to northern California. Typically, they pass through the Seattle area from February to July pausing for a week or two to refuel for their last flight to their northern breeding regions. They seldom stay in one place very long.

We’ll talk more about Rufous Hummingbirds and the other two possible hummingbird visitors to Seattle, in our next blog.