Saturday, July 21, 2012

A Stick in the Mud

            In 1973, the Endangered Species Act (ESA) was passed by the Nixon administration in order to protect rare and declining wildlife across the country. Without this legislation, many species would undoubtedly be in more trouble than they already are. Since its passing, 28 species have been delisted due to recovery, including the bald eagle, the grizzly bear, and the american alligator (USFWS, Delisting Report, 2012.

As the bane of developers, the ESA stipulates that there cannot be any actions taken to harm populations of threatened (T) or endangered species (E)—threatened meaning is likely to become endangered, endangered meaning in danger of extinction—or the ecosystems in which they reside. It is a rather involved process to get a species listed under federal protection via the US Fish and Wildlife or NOAA, but once protected, there are serious consequences for harming a T&E species.

An adult bog turtle with the mud rinsed off. Notice the orange cheeks.                  

            A current threatened species that I have gotten to work with is the bog turtle (Gleptemys muhlenbergii “Muhlenberg’s Carved Turtle”), which has separate populations in the Southern Appalachian Mountains and the Northeast. Occupying bogs, swamps, and wet meadows, the bog turtle requires slow-flowing rivulets and mucky, organic soil. Their habitat has some of the richest plant diversity, with small bogs or wetlands having over 150 plant species. Because of their habitat requirements, this species has declined as wetlands have been drained, cultivated, and developed.

      A bog turtle nest (above) is usually laid right in the middle of a tussock sedge, so that it can incubate.      
Between predators, weather, and other factors, only about 27% of eggs make it to hatchlings (below).

             Considering bog turtle habitat, it is no wonder the species are declining. Walking through the bogs, one can sink two feet into muck while trying to avoid poison sumac. Surveying for turtles can involve trapping with wire boxes, or, more commonly, probing in the mud. You would never guess that poking around in deep mud will yield turtles. The trick is learning to discern the “thud” of hitting a submerged root from the “thwok” of a rock from the hollow “thunk” of hitting a bog turtle carapace.

Imagine trying to hit that shell through a foot of mud without knowing what exactly you
are hitting. A sometimes frustrating, but rewarding, treasure hunt.

            Once found, the turtles are notched, measured and released so that the overall population can be estimated with mark recapture analysis. If a turtle is lucky, it will get decked out with a radio transmitter. I can’t decide if the transmitter is poorly respected (like a dog with a head-cone), or highly prized (like a geek with the newest gadget). Anyways, tracking and recording the locations of the turtles using radio telemetry help scientists understand how much habitat is required to sustain a population and what type of sub-habitat, or microhabitat, the individuals prefer.

An adult bog turtle with a radio transmitter attached to the carapace.
The transmitter is placed on the side of the posterior so that it does not hinder movement or mating.

            All in all, the bog turtle is a very neat species, burrowing and moving around underneath mud and adding a little character to a rare and unique habitat.

Information on bog turtles taken from studies reported in Turtles of theUnited States and Canada by Ernst and Lovich

Saturday, July 14, 2012

On the Road Again

(Disclaimer, if you don't like animal guts, skip this post).

Also, double post this weekend, so don't miss “Quoth the Marsh”

Most normal people would not consider any road kill all that special, particularly if it is a snake. Even though I am human, I most likely wouldn't fit the bill for being normal. Naturally, when I saw a Eastern Common Garter Snake (Thamnophis sirtalis sirtalis) dead on the road, I had to pull over and snag it.

 The specimen in question. Depending on the subspecies,
it can take two the three years before females can reach reproductive maturity

Now, even further from being normal, I decided to dissect the snake so that I could try and get a whole snake skeleton to put together as a model. It was also a unique opportunity because she was gravid, and you could feel the embryos in her gut.

Common Garters are not having too hard of a time compared to most snakes, but it is still sad to see a gravid female killed by a car. There were a total of five embryos inside her. Garters are ovoviviparous, meaning that they produce offspring within an amniotic sac and give live birth. It takes 80 to 90 days for gestation to occur (depending on environmental temperature), and a female can birth between 1 and 101 offspring depending on size and maturity. Females will only breed bi-annually or tri-annually. 

One of five embryos inside the snake. It's rare to get to see offspring
mid-development. The top picture shows the developing snake inside its own membrane.
The second shows it outside of the membrane.

Interestingly, the Common Garter snake is the northernmost snake species in North America. This is because it can tolerate a wide range of temperatures and can even survive being frozen for brief periods of time. Found in a variety of different habitats, the snake is most commonly found near wet areas. As there are many subspecies of this snake, coloration, diet, and behavior can vary drastically.

The Common Garter Snake is also the most deeply studied snake in North America.

For more info, see Snakes of the United States and Canada by Ernst and Ernst

Quoth the Marsh

As the main research branch of the United States government, the US Geological Survey (USGS) does a lot more than look at rocks. They produce many of the research protocols that the National Wildlife Refuge system follow, and this includes the monitoring of many different taxa: streamside salamanders, vernal pool amphibians (see post), songs birds, waterfowl, and many more.

These guidelines for wildlife monitoring mean that nationwide, there are standardized surveys going on, giving the USGS significant insight as to how wildlife populations and species distributions are changing. One of the surveys that we have conducted as part of these protocols include “Secretive Marsh Bird” surveys.

Walking to the first marsh for surveying. Multiple marsh locations are done within
a 4-5 hour window of time during specific weeks of the year.

Like many bird surveys, early morning hours are required, and in this case, they are required along with a portable speaker system. Many of the birds that are obligate marsh birds—meaning they are only found in marshes—are extremely hard to see. In order to survey for them, we play a sequence of bird calls with hopes that these birds will return the call. As with many birds, secretive marsh birds are territorial. Thus, they think the call we play is an obnoxious intruder, and it is their duty to let the intruder know that turf (or surf?) is already taken.

 Clapper Rail. Photo by L. Meyers

 Green Heron. Photo by M. Godwin.

Some of the species that are targeted include the Least Bittern, American Bittern, Sora, Green Heron, Virginia Rail, and Moorhens, and Clappers. While many people think of Great Blue Herons when they think of marsh birds, Great Blues are not considered obligate marsh species, as the herons can be found along streams and other habitats as well.

Least Bittern. Photo by