Five rivers feed into the 200,000+ acres of wetlands that make up the second largest river delta system in the U.S. just north of Mobile Bay in southern Alabama. The Mobile-Tensaw delta’s expanse of swamp, bog, natural rice paddies, canals, and rivers makes this area of Alabama a real biodiversity hotspot where you can find more species of fish, turtles, snails, crayfish, and oak trees than anywhere else in North America. Harvard ecologist E.O. Wilson has called it North America’s Amazon, and so it was a real treat to venture out on a small boat to explore some of the smaller waterways of the delta for ourselves.
The southeastern U.S., and the Mobile delta in particular, was a refuge for species driven south during the ice ages of the Pleistocene glaciation. Warm temperatures year-round and plenty of rainfall (averaging 70 inches per year) ensure the most equitable conditions for life to survive, and so it has in this cradle of biodiversity.
We took a car ferry to Dauphin Island which sits at the mouth of Mobile Bay, and then drove west to Pelican Point beach for a (hot) walk in the late morning sun. The beaches along the gulf coast of this part of Alabama are composed of finely ground, minuscule particles of quartz that originated in the Appalachian mountains, were ground down by erosion and river action before being transported to the gulf, where minerals were further reduced in size by wave action over tens of thousands of years. The result is an eye-blinding, fine, white sand that actually squeaks as you walk over it.
Florida has the distinction of being the epicenter of invasion of non-native reptiles, introduced by collectors who intentionally or unintentionally let non-natives escape, or by accident when eggs or small hatchling reptiles are carried into this country on imported plants.
Successive invasions of Brown Anoles from Cuba and the Bahamas since the late 1800s have resulted in well established populations throughout Florida that have since moved north and west to Georgia, Louisiana, and Texas, and have also resulted in an apparent coincident decrease in the population of native Green Anoles.
However, rather than disappearing altogether as a result of the Brown Anole invasion, it may be that Green Anoles simply move out of the low vegetation and up into the tree tops where they can more favorably compete for food and avoid being eaten by the more aggressive Brown Anole.
A couple of pristine white and almost perfectly round Giant Puffball mushrooms appeared in the wetland behind the backyard about two weeks ago.
These distinctive Fungi have no spore-bearing gills on the underside like most table mushrooms. They do not have a stalk or stem, and the spores produced internally are released in a cloud of brown dust when the large fruiting body splits apart at maturity or due to some mechanical disturbance (like someone kicking it).
Every couple of days I visited the “twins” to see what changes had occurred in the interim. The figure below captures the progression of changes in the largest Puffball over almost two weeks. Click on the image to get a larger view.
Giant Puffballs can grow to 20-inch diameters, and occasionally the largest ones may be up to 60 inches across and weigh as much as 40 pounds. They are edible when young with firm, solid white tissue inside. But as they mature and begin to decompose, the interior spore development becomes a soft greenish brown as trillions of spores develop.
Here’s a fascinating video on the spore production of Puffballs by Sir David (Attenborough) and some nifty time-lapse video of Earth Star fungi that puff their spores out in response to rain…
A little Spotted Sandpiper had the entire beach of Vadnais reservoir to itself and moved slowly along the shoreline probing now and then in the mud and under leaves as I stood quietly and watched.
Spotted Sandpipers are likely the most widespread breeding sandpiper in North America, nesting from northern most Alaska to the mid-continental U.S. along rivers, lakes, and streams.
And their breeding system is particularly interesting because they exhibit a sex role reversal compared to most other bird species. Instead of the typical female role of incubation and hatchling care, Spotted Sandpiper females “collect” multiple males, laying a clutch of eggs in each male’s nest, which he will then incubate. After they hatch, the male is in charge of protecting and providing food for the chicks, while the female goes off to find another male to mate with.
Female Spotted Sandpipers arrive first on the breeding ground, establish their territory, and then compete with each other for males to mate with. Since females can store sperm from multiple matings for up to a month, the male may be incubating and tending to chicks that are not his offspring! This breeding strategy, called polyandry, is rare among birds but is found in several shorebird species, in Northern Jacanas, occasionally in Acorn Woodpeckers, and in Harris Hawks.