Red maples in flower. Photo by W. Hamilton
(Click on the following link to listen to an audio version of this blog … Florida 4 woods and swamps 2
(More on our hikes on the Ron Sapp Egans Creek Greenway Trail on Amelia Island.)
Red maples (Acer rubrum) were very abundant along the Greenway trails. They grew in wet lowlands and also up on the drier hillsides. They hadn’t made any leaves yet, but, like the red maples up in Pennsylvania they had flowered well before setting leaves and had made large numbers of bright red seed samaras. The samaras were larger (about twice as long!) than the samaras I remember from my red maples back in Pennsylvania. This intense red color stood out against the drab grays and browns of the “stick” forest. As I have previously said with regard to Pennsylvania forests (see Signs of Spring 8, April 14, 2016), late winter or early spring is the time to do a census of just how many red maples are in these forested ecosystems! It is quite obviously the most numerous tree species in the northern and also the southern Eastern forest!
Woods along the trail. Photo by W. Hamilton
Along with the reds from red maples, there were also splashes of green in the woods. These grrens were from scattered sweet bay magnolia (Magnolia virginiana), dwarf palmetto (Sabel minor) and slash pines (Pinus elliottii). There were also several, medium-tall, leafless trees that had a very characteristic branching pattern. The main branches of the tree out to all of its terminal twigs arose directly opposite each other, there was no staggered or alternate branching at all. These had to be ash trees, and looking up the types of ashes expected in these wet swamps, I assume that they were pop ashes (Fraxinus caroliniana).
Photo by D. Sillman
Another source of green colors along the hiking trail were the small, floating, water plants that covered almost all of the surface water of the swamp pools. This is a familiar plant species that invasively plagues many freshwater ecosystems back in Pennsylvania: duckweed (a variety of species in the sub-family Lemnoideae). Under normal conditions, duckweed’s rapid growth is balanced by a rapid dispersal rate. Also, the rate of its consumption (it is a high protein food eaten by many birds (waterfowl), fish and amphibians) balances its rapid rate of reproduction. When duckweed grows in water that is enriched in nutrients (like fertilizer runoff for example or phosphate pollution from household detergents), though, it can reproduce so rapidly that it overwhelms its aquatic ecosystem.
Great blue heron. Photo by D. Sillman
Wood stork. Photo by D. Sillman
There were many birds both in the swamp and out in the salt marsh beyond. A flock of broad winged hawks ( Buteo platypterus) kettled past overhead in great swirling arcs. A number of black vultures ( Coragyps atratus), mostly flying alone or in pairs wobbled by in very straight-line flight paths. And, perched on the partially submerged logs of the swamp pools and slogging through the muddy waters were anhingas (Anhinga anhinga), white ibises (Eudocimus albus), great egrets (Ardea alba), great blue herons (Ardea herodias) and a tall, powerfully beaked wood stork (Mycteria americans).
We saw several American alligators in the ponds and pools along the trail. Most of them were quiet and seemed quite sluggish in the cool mornings almost to the point of profound immobility, but alligators can get very busy very quickly and move surprisingly rapidly when the need arises!
As I wrote in a blog back in 2019 (Signs of Fall 3, October 3, 2019), the American alligator was brought back from the edge of extinction by the protections of the Endangered Species Act of 1973. It now can be found in both freshwater and brackish habitats from the wetlands and lakes of Texas, all across the states bordering the Gulf of Mexico, and up the U.S. Atlantic coast as far north as North Carolina.
Why was it important to re-establish this formidable reptile in its former ecosystems, and why is it important to maintain them there? The answer revolves around the keystone nature of this species.
American aligator. Photo by D. Sillman
First and foremost, the American alligator is a predator. It opportunistically takes almost any prey species that comes into its strike zone. It especially eats large prey species that live in their aquatic habitats (especially large fish), and they also eat a wide range of terrestrial species that wade or swim across their aquatic habitats or come to the edge of their pools, ponds or streams to drink). American alligators have been known to take black bears, panthers, deer and wild boar but more commonly capture and eat smaller terrestrial prey like raccoons and muskrats. Control of these prey species is a very important ecological role of this species.
A very interesting “unintended consequence” of the extirpation of the American alligator from wetlands in Florida (which was motivated in part at least to stop the alligator’s consumption of game fish) was the precipitous drop in game fish populations after the alligators were gone. Researchers determined that the alligators preferentially consumed large fish (like gars) and that these large gars preferentially ate the game fish. Without the alligator-mediated control of the gar population, game fish numbers drastically declined.
American alligators also construct “gator holes” or “gator ponds” in their wetlands. The alligator uses its snout and tail to dig down through the accumulated muck and vegetation to create a relatively deep water pool in which it can hide and hunt. These pools fill up with freshwater and are often the only water sources that persist during times of drought. Many animals rely on these gator holes for drinking water during times of low rainfall (although they have to keep an eye out for the lurking, hunting alligator!).
Female American alligators also modify their wetland habitats via the construction of nesting mounds. These mounds can be as much as 3.5 feet high and up to 7 feet wide. These mounds serve not only as incubation sites for the alligator eggs but can also can significantly add to the topographic complexity of the wetland habitat. A variety of plant species that require slightly drier soils can grow on these mounds thus increasing the vegetative diversity of the wetland. Also, a significant number of bird and mammal species can use these mounds for their own nests and dens.
Chicken turtles on a log. Photo by D. Sillman
We saw quite a few turtles in the pools and ponds along the trail. There may have been more than one species, but this photograph enabled me to identify this “turtle train” as a set of chicken turtles (Deirichelys reticularis). Most of the turtles we saw in the still waters of the swamp forest were probably chicken turtles.
Chicken turtles are almost exclusively carnivores. The larger female chicken turtles especially eat larger prey like crayfish. The smaller chicken turtles (the males and the immatures) typically eat smaller prey like dragonflies, spiders and tadpoles. Chicken turtles are also know to eat carrion and, rarely, vegetation.
Chicken turtles are aquatic, but they regularly spend many months of the year on dry land (typically in forested habitats). The transient nature of many of their marshy pools and the high probability of their muddy ponds seasonally drying up is a logical ecological and evolutionary motivation for their adapting to occasional life in dry habitats.
(Next week: Manatees!)