Saturday, March 24, 2012

Amphibians on the march

Last night was plenty warm and lots of wet, so I headed over to a favorite amphibian hotspot not far west of Columbus. Lots of animals were on the prowl, moving overland to breeding pools. In just two hours, and covering only a short stretch of road, I saw scores of frogs and toads, and a surprising number of Ambystoma salamanders. Sorry for the smudgy spots on some photos - they're caused by rain drops on my lens. Try as I might, it was impossible to keep the camera totally dry. It was truly a dark and stormy night, after all.

A male spring peeper, Pseudacris crucifer, makes himself known. Scores of the quarter-sized amphibious blowhards were singing in this vernal pool, and the shrill high-pitched peeps are nearly ear-splitting when one is up close and personal. From my experience, the best way to study frogs is to get in the pools with them at night when they are vocalizing.

A young American bullfrog, Lithobates catesbeianus, hops his way across the road. On a good migratory night, such as last evening, it is truly astonishing how many frogs of multiple species can be seen on the roads. Most of the lanes that I explored last night are lightly traveled country roads, but even so the mortality from vehicles is high.

A big old green frog, Lithobates clamitans. A smudge of rain partially obscures its tympanum, or "ear" - just aft of the eye. In females, the tympanum is about the same size as the eye; in males it is noticeably larger. This one looks to be a female.

There were a lot of American toads, Anaxyrus americanus, moving last night. Many were in full song, their sonorous droning trills echoing from the wetlands.

This little toad stretched up, the better to see the annoying paparrazi who was flashing him in the face.

"Enough", says the warty little fellow!

I was surprised to see how many salamanders were still moving. Given the extended warm weather that we've had, coupled with plenty of rainy nights, I figured they would pretty well be done for the year. But in short order, I saw a few dozen spotted salamanders, Ambystoma maculatum. The road that I spent most of my time on is buffered by wet woods full of vernal pools on either side, and plenty of salamanders were crossing back and forth. I'm sure I saw but a small percentage of the animals that were moving last night.

Outnumbering the spotted salamanders were the bizarre "unisexual" salamanders. These animals are part of a hybrid swarm: a complex of all females that have genetic contributions from small-mouthed, Jefferson, blue-spotted, and tiger salamanders. Should you be interested in learning more about these amphibious oddities, CLICK HERE.

A heavily blue-flecked individual makes its way across the road. Presumably this patterning is the result of its blue-spotted salamander lineage. Its tail also caught my eye. It seemed exceptionally thick and compressed, and reminded me of the shape of a tiger salamander's tail. There are plenty of tiger salamanders in this area, but I don't know how much of a role they play in forming the local populations of unisexual salamanders.

The annual spring run of amphibians to the breeding wetlands is one of spring's great natural events. This was probably one of the last good migration nights around here, and likely the last night of the year that I was able to get out and look. Another year will have to pass before I get to observe this phenomenon again.

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4 comments:

Nature in the Burbs said...

Great shots.

Sharkbytes said...

Awesome pictures. I'm off to read about the hybrid salamanders.

Jack and Brenda said...

What a nice selection!

pambirds said...

LOL - the little toad warding of the paparazzi was absolutely a hoot!