Saturday, March 14, 2015

The amphibian exodus

Wood Frog (Lithobates sylvaticus)

Late last night, returning from a jam session with my friend Alex, I saw frogs like popcorn on the rainy roads. I even saw (and narrowly avoided squishing) a salamander army-crawling across the nature center driveway. And so I decided to go for a midnight amphibian hunt even though I craved sleep.

Such nights are ideal for finding frogs and salamanders. Amphibian movements are dictated by rain--their skin must remain moist, and some individuals traverse hundreds of meters of high ground to reach their breeding pools. Moving at night presumably ameliorates desiccation and lends security from predators.

They covet vernal pools, those ephemeral puddles that will dry by July. These temporary ponds cannot house fish and other aquatic predators, creating a safe nursery for amphibians. But, the amphibians can't waste their time--the pools will dry, and if the larvae cannot mature, they perish. Starting in late February and early March, the salamanders stage a sluggish exodus from their subterranean hovels to their ice-rimmed breeding pools.

As I hiked through the persistent rain, I imagined seething masses of salamanders and cautiously planted each step to avoid pancaking any migrating amphibians. The scene at the first pool I visited was much less exciting than I had imagined--a few chilled Wood Frogs floated around, but nothing else. I had to search for ten minutes until I found my first Jefferson Salamander.

Jefferson Salamander (Ambystoma jeffersonianum)

I moved on to a second pool. This one throbbed with frog activity. I could hear the Spring Peepers from a quarter-mile away, and as I drew close, I could Wood Frogs gurgling the base line to the frog cacophony. The frogs, chilled and hormone-charged, were easy to catch.

Spring Peeper (Pseudacris crucifer)

Wood Frog (Lithobates sylvaticus). Crawling onto a sheet of ice isn't such a great decision when you are a poikilotherm!

No salamanders. I probed the shallow water with the beam of my headlamp, but the hunt was fruitless. Finally, out of desperation, I cast my net into the pool and dredged a three-foot section of the pool's bottom. To my astonishment, the net came up with a Spotted Salamander! I couldn't duplicate this feat despite casting the net a dozen more times.

Spotted Salamander (Ambystoma maculatum)

And finally, this evening, while seeking woodcocks at Shor Park, I came across this fearsome salamander that I cannot identify

Just kidding--it's a crayfish, of course. I decided to overcome my deep-seated fear of crustaceans and picked it up. I didn't even get pinched! I can highly recommend the experience. Don't be afraid.

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