Vernal Pools
Well, now that the last snowstorm of the season is over (I hope) it truly is the start of spring. One good thing about the snow is that it will feed the vernal pools in the region. These temporary bodies of water usually go dry by mid-summer so they don't support fish. This lack of large predators makes the pools critical habitat for the first stages of life for many amphibians.
In Massachusetts, the two most common vernal pool amphibian species are Wood Frogs and Spotted Salamanders. The Wood Frog is truly an incredible animal. It spends most of the year in the woods. As winter approaches it seeks a hiding place in the leaf litter and proceeds to freeze virtually solid. The frog has developed special adaptations to allow it to survive this freezing process. When the temperatures drop, the frog's body produces large amounts of glucose. This blood sugar acts as a type of "anti-freeze", preventing the frog's cells from freezing along with the water in its body.
When the ice melts, the frogs reanimate. This event was captured by Jeff Corwin in his Animal Planet show, Corwin's Quest. Jeff went out in the dead of the Massachusetts winter and chipped a Wood Frog out of the ice. After an hour or so inside, the ice had melted enough to allow the Wood Frog to break out (kind of like it was in an egg). It really is incredible to watch.
Passing the winter on land allows the Wood Frog to be the first to the mating grounds. Hundreds of individuals gather in vernal pools and pairs enter amplexus. The males grip the females around the waist and hold on tight. This allows them to be in position to fertilize the female's eggs as they are laid. After this short period in the pool, the adult frogs disperse back into the woods.
The Spotted Salamander also uses vernal pools for mating. These animals are a member of the mole salamander family, so named because they spend almost the entire year underground. The only time that you're likely to find them is during rainy nights in March/April when they emerge to mate. I've been lucky enough to see a few of these salamander at a set of vernal pools in Sutton. They are truly huge. I'd estimate about 10 times the size of a Redback Salamander (a species which more people have probably encountered).
But, these are only a two of the species that rely on vernal pools. Snakes, turtles, fairy shrimp, and all sorts of insects live or feed at the pool. If you're interested in these animals, I'd recommend getting a copy of "A Field Guide to the Animals of Vernal Pools" by Leo P. Kenney and Matthew R. Burne. this is a small but unbelievably useful guidebook. I have a copy and keep it in my pack for quick reference whenever I'm out in the field.
Another great resource for more information on vernal pools is The Vernal Pool Association's web site. The association even has a listserv for discussions on the subject.
In Massachusetts, the two most common vernal pool amphibian species are Wood Frogs and Spotted Salamanders. The Wood Frog is truly an incredible animal. It spends most of the year in the woods. As winter approaches it seeks a hiding place in the leaf litter and proceeds to freeze virtually solid. The frog has developed special adaptations to allow it to survive this freezing process. When the temperatures drop, the frog's body produces large amounts of glucose. This blood sugar acts as a type of "anti-freeze", preventing the frog's cells from freezing along with the water in its body.
When the ice melts, the frogs reanimate. This event was captured by Jeff Corwin in his Animal Planet show, Corwin's Quest. Jeff went out in the dead of the Massachusetts winter and chipped a Wood Frog out of the ice. After an hour or so inside, the ice had melted enough to allow the Wood Frog to break out (kind of like it was in an egg). It really is incredible to watch.
Passing the winter on land allows the Wood Frog to be the first to the mating grounds. Hundreds of individuals gather in vernal pools and pairs enter amplexus. The males grip the females around the waist and hold on tight. This allows them to be in position to fertilize the female's eggs as they are laid. After this short period in the pool, the adult frogs disperse back into the woods.
The Spotted Salamander also uses vernal pools for mating. These animals are a member of the mole salamander family, so named because they spend almost the entire year underground. The only time that you're likely to find them is during rainy nights in March/April when they emerge to mate. I've been lucky enough to see a few of these salamander at a set of vernal pools in Sutton. They are truly huge. I'd estimate about 10 times the size of a Redback Salamander (a species which more people have probably encountered).
But, these are only a two of the species that rely on vernal pools. Snakes, turtles, fairy shrimp, and all sorts of insects live or feed at the pool. If you're interested in these animals, I'd recommend getting a copy of "A Field Guide to the Animals of Vernal Pools" by Leo P. Kenney and Matthew R. Burne. this is a small but unbelievably useful guidebook. I have a copy and keep it in my pack for quick reference whenever I'm out in the field.
Another great resource for more information on vernal pools is The Vernal Pool Association's web site. The association even has a listserv for discussions on the subject.
posted by Mike @ 11:02 AM
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