Dune with beach grass. Photo by Ellyway. Wikimedia Commons
(Click on the following link to listen to an audio version of this blog …. Florida 2 beaches and dunes part2
(Continuing the discussion of the beaches and dunes of Amelia Island, Florida)
The seaward face of the first dune (the “primary dune”) rises steeply from the gentle upward slope of the dry, upper beach. The exposed face of this primary dune is, on average here in Amelia Island, four or five feet tall and is made up of loose sand that is dominated by relatively coarse sand grains. The upper beach and the primary dune face are heavily used by people visiting the beach. They are well covered with foot prints and indentations where coolers, bags, folding chairs and beach gear have been stashed. In some places the front of the dune have been worn down by the passage of the feet of many visitors.
Near the top of sea-facing dune the beach grasses begin. These plants have fantastically deep roots and are also able to tolerate the salt spray that blows in from the waves crashing down on the intertidal beach. These beach grasses continue down the gentle slope of the landward side of the primary dune and continue in clumping distributions back through the undulations of the subsequent dunes and their interdunal recesses.
The sand grains on this leeward dune face are smaller and, therefore, lighter in weight than the sand particles in the seaward facing part of the dune. The onshore winds have pushed the heavy sand particles to the front face of the dune and blown fine clouds of smaller sand particles up over the peak of the dune where they have scattered and slowly settled out on the leeward slope.
Back dunes. Photo by D. Sillman
The beach grasses generate favorable microhabitats for the growth of other plants. These other plants cluster around the beach grass clumps and then begin to fill in the open spaces around the clumps. Palmettos (scrub palmetto?), bay laurel, thistle and opuntia cactuses (“prickly pears”) along with an array of low growing flowering plants make the interdunal areas and, eventually, the dunes themselves increasingly dense, shrubby vegetative habitats.
Shrubby back dune. Photo by D. Sillman
In a natural system, these shrubby communities would further develop into pine dominated maritime forests, but here on the Amelia Island coast, a bordering line of condos, beach houses and roads has been built on the site of the old maritime forest. There are, though, patches of maritime forest at the northern end of Ron Sapp Egans Creek Greenway trail (and I will describe this trail in a future blog). In these truncated sand dune systems, the primary dune is the tallest and most substantial dune. Behind it, to landward, are typically a set of 3 to 4 small dunes that stretch back the 30 or 40 yards to the front edges of the buildings built along the dune-front road.
These secondary dunes are poorly structured and don’t seem to be a very substantial protective barrier for the land. A very nice feature of these “back dunes,” though, are the elevated walkovers that keep beach-goers from trampling on the delicate dune surfaces. These wooden walkways connect the streetside parking lots with gaps in the primary dunes and allow foot traffic back and forth over the secondary dune systems.
Gopher tortoise in back dunes. Photo by D. Sillman
These walkovers also provide a good perch to observe some of the animals that live in the interdunal habitat. I saw several gopher tortoises (Gopherus polyphemus) lounging in the openings of their burrows. Gopher tortoises are an endangered species whose population numbers have been decimated by habitat degradation and loss. These tortoises are also keystone species in their dune ecosystems. Their burrows are, according the Florida Fish and Wildlife Commission, important refuges for over 350 native animal species including the threatened Eastern indigo snake, the burrowing owl and the gopher frog. This tortoise is protected by both Federal and Florida law.
Pausing on a walkover to watch a tortoise slowly tear apart a pumpkin that someone had dropped for him, I spoke with a gentleman who owned the beach house that edged that stretch of dune. He called the dune system his “front yard” and was very attentive to the gopher tortoises living there. He said that he didn’t know who had given the tortoise the pumpkin but said that he often put out lettuce and apples for “his” tortoises.
Marsh rabbit. Photo by W. Hamilton
Also living in the secondary dunes and visible from the walkover are marsh rabbits (Sylvilagus palustris) (also called “marsh hares”). Marsh rabbits are small, brown cottontail-like rabbits with comparatively short ears and legs and small tails. They are known to be extremely strong swimmers and are quite abundant in the marshy areas of the coastal islands. I had the pleasure of seeing one of these rabbits darting about while I was watching a tortoise slowly doing nothing at all!
I had expected to see quite a few birds down on the beach, but the numbers were disappointing. My guess is that overwintering birds would probably be located further south in the warmer sections of southern Florida. I did see a few least sandpipers (Calidris minutilia) and some spotted sandpipers (Aactitis mcularius) in their unspotted, winter plumage probing the sands just at the tideline and moving steadily southward down the beach.
Herring gulls (Larus argentatus) were very precisely scattered across the intertidal and upper beaches. The individual birds were almost always solitary and maintained a distance of 20 or 30 yards from their nearest neighbor even as they moved up and down the beach. The much smaller laughing gull (Leucophaeus atricilla) mixed in and around the herring gulls and were much more randomly spaced on the beach. The laughing gulls often bunched together and then quickly dispersed only to form new groupings several feet way.
I also saw one immature bald eagle (Haliaeetus leucocephalus) flying overhead one afternoon. He flew out just over the ocean waters and raced south at a very impressive speed. He was out of sight, in fact, in what seemed like just a few seconds!
I did see quite a few birds on my walk through a wetland forest. I will talk about those in another blog.
Two color forms of A. carolinensis. Female has light back stripe. Photo by R. Michniewicz. Wikimedia Commons
At Randy and Charlene’s rental house I also saw a number of reptiles and birds. The side of the house and the surrounding philodendron bushes and palmettos were alive with small, green anole lizards (Anolis carolinensis). The green anole is native to the American Southeast and has a range that extends all the way over to the Texas Gulf Coast. We had these “chameleons” (a very common name even though they are not really chameleons at all) all over our house in Houston. Even though they are not true chameleons, they do have the ability to change their body color. They can change from green to brown depending on their need for specific camouflage. These lizards eat all sorts of insects and spiders and are, in turn, eaten by many birds, larger lizards, snakes and dogs and cats. Many years ago, I made an 8 mm movie of my cat, Sam, hunting and eating anole lizards back in Houston. Unfortunately, that movie has been lost in the clutter of time!
Eastern black racer (coiled next to wall). Photo by W. Hamilton
We also had a daily visitor at the rental house who curled up next to the side of house under the cover of the palmettos. Depending upon the morning temperatures, he would show up in the early morning or, sometimes, later in the day. Deborah and I had a ritual with our first cup of morning coffee to go over to the corner window of the sunroom and say “good morning” to “our” snake!
He was an Eastern racer (Coluber constrictor). I estimate that he was 2 to 2 ½ feet long, but he was so tightly coiled up on the dry leaves and sticks under the bushes that it was hard to precisely tell. He was relatively thin, solid black on his back and sides (I couldn’t see his belly). This uniform dark coloration indicated that he was an adult. I assume that he was primarily living on the green anole lizards who were darting around on the branches above him, or maybe on the little rodents scuttling around in the vegetative debris of the shrub beds. Racers are the most common snake found in Florida neighborhoods. They eat small rodents, lizards, frogs, toads, and insects. They can also climb into birds’ nests and eat eggs and nestlings.
Also at the rental house I saw a bird that I have missed very much since we moved to Colorado: the northern cardinal (Cardinalis cardinalis). Cardinals were one of our most abundant birds around our old home back in Pennsylvania, but they aren’t found as far west as Colorado. It was wonderful watching them fly about in their mixed flocks with titmice, chickadees and Carolina wrens around the dense array of tree limbs that bordered the rental house’s back yard!
(Next week: hiking on the Greenway Trail!)