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Guest Column: Not so Silent Spring – Frog Calls in College Park

[By Rick Borchelt. Rick lives in College Park and writes a blog here http://leplog.wordpress.com/]

College Park is extremely fortunate to have several vernal pools that attract frogs and salamanders early each spring to call and mate. A vernal pool is defined as a temporary pool of water, generally without fish, that dries up at some point in the year (hence the no-fish condition). This is very important for frogs and salamanders, whose eggs and tadpoles are usually wiped out where there is fish predation. Vernal pools typically fill up from winter rains and snow melt and dry out in July and August, giving tadpoles a chance to metamorphose into young frogs and leave the water.

The vernal pool most convenient to watch and hear this spring ritual is located between the Tot Lot and the Metro Parking on Columbia Ave. in Old Town. It’s fenced off, but you can get pretty close from the Tot Lot side, and even listen pretty well from the north end of the College Park Metro platform.

On warm nights for the next couple of weeks you’ll be able to hear at least three different frogs calling from this vernal pool, which is the remnant of a series of pools and marshes that used to stretch all the way from the Anacostia up to Laurel, and of which Artemesia is also a remnant (although it used to be shallow pools instead of the large lake formed when dirt was removed to build the Greenbelt Metro). Late in the afternoon and continuing through the early evening, stand by the swingset on the south end and listen for:

Spring Peeper. This small frog, about the size of a quarter, is the loudest in the pool. It “peeps” single, high-pitched notes by inflating an air sac in front of the frog on its throat. When large numbers of them are calling (called a “chorus”) it can make it very hard to hear the individual peeps inside the wall of sound. These are all males calling and advertising their sexual prowess; females listen on the sidelines and then gravitate toward the singer they prefer. The males typically sing from grass or branches or leaves sticking out of the water.

Spring Peeper call:

Wood Frog. This is the largest frog right now in the vernal pool (Green Frog and Bullfrog will be larger and will show up later). It’s 3-4 inches long. Their call sounds like “quacking” or “growling”; their air sacs are on the sides of their throats, so they balloon out on both sides. These frogs float in the water as they call, and you can actually see the waves on the water from the inflation of the air sacs and the males jockeying for females. Most of the Wood Frogs are in the deeper water on the end of the pool nearest the Tot Lot.

Wood Frog call
Wood Frog video:

In the background of the Wood Frog video you can also hear a call that sounds like fingers being run over a comb. This is a Chorus Frog, and that’s the third species you’ll hear calling from the Columbia Ave. vernal pool. These are also about the size of a quarter and very closely related to Peepers. There are only a few males calling from the Old Town pool, mostly on the side nearest the railroad tracks.

Upland Chorus Frog call:

Later in the season, listen for toads calling in chorus. They’ll sound like a distant diesel engine motor revving up.

Vernal pools are among the most endangered habitats in Maryland; they’re often drained for development or in the erroneous belief they harbor mosquitoes. Every effort should be taken to preserve these fragile habitats.

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