Sunday, March 4, 2012

Spotted salamander

A gorgeous pair of spotted salamanders, Ambystoma maculatum, rear up to investigate your narrator. These odd blue-gray amphibians, patched with flakes of gold, rise from their subterreanean haunts but once a year, and your window of opportunity to observe them is brief.

Fortunately, two speaking obligations over the past few days took me to Adams County in southern Ohio, and at prime time for the eruption of salamanders. Not one to shun fieldwork, I managed to wet my feet and visit some of our most interesting and poorly known creatures as they made their vernal peregrinations to their breeding pools.

Naturalist extraordinaire John Howard, a native of Adams County, led us on a field trip to this vernal pool as part of a symposium entitled "Vernalpalooza" (more on that event later). Vernal pools are, in general, ephemeral wetlands - they hold water for only the wet spring months, and many of them dry up by fall. Many of Ohio's vernal pools are small; often well under an acre. The one in this photo was an acre or so - about the size of a typical suburban lot - but was full of life. A key requirement is that these vernal pools lack fish. Most fish are voracious predators, and the scores of amphibians that migrate to vernal pools wouldn't stand a chance if bass and bluegills were waiting. This is why it's important that vernal pools go dry seasonally - it precludes the establishment of the finned crowd.

Long, low, and moist as a sponge, a spotted salamander stalks towards the pool. This species and its Ambystoma kin are commonly known as "mole salamanders". That's an apt moniker, as salamanders in the genus Ambystoma spend nearly their whole lives under the ground. They're avid predators of eathworms and other subterranean critters - probably few things smaller than they are, are safe. Occasionally one stumbles into a mole salamander while turning logs or rocks, but for the most part they remain inaccessible until the great spring migrations.

Spotted salamanders are rather large stout beasts. They can get bigger than this, and some old gravid females are quite impressive in scale.

A disheartening number of mole salamanders meet their demise on roads, flattened by vehicles. The drivers are probably oblivious to the carnage that they cause; the salamanders are very hard to spot on dark wet roadways.

When the first warm rains of late winter/early spring arrive, it is as if giant magnetic fields tug the salamanders from the earth. They arise en masse, like an army of amphibious zombies, and march towards ancestral breeding pools. Nothing deters them, including roads. If one is interested in witnessing this spectacle, it is necessary to be be on alert and ready to act on short notice. The salamanders will not be above ground for long, and interested observers must work on their terms.

John Howard and Tricia West admire a road-going spotted salamander that is crossing a rural Adams County lane. We were out road-cruising and vernal pool wading for about four hours last Friday night, and saw hundreds of salamanders.

That night had a strange beat to it. A vicious string of tornados - some of the strongest on record - had laid waste to southwestern Ohio and nearby Indiana and Kentucky earlier in the day, claiming numerous lives and causing lots of property damage. I rode it out in my hotel at Murphin Ridge, and thought the roof might come off the place at one point. The storm took out all the power in the area, and I was sad to learn that The Nature Conservancy's venerable old barn along Ohio Brush Creek was utterly flattened by the high winds. Trees were down everywhere, and the eerie pulse of the tornado's aftermath could still be sensed that evening. By the time we ventured out, the rains had ceased, but the ground was thoroughly saturated as it must be for the salamanders to launch on their march. Strong winds scudded broken tiers of clouds across a starry backdrop, the intermittent bursts of dim moonlight briefly lighting the migrating amphibians.

A strange sight indeed, and this was even stranger in person. The photo shows a salamander that has briefly lunged to the water's surface and is grabbing a quick breath of air. John guided us to a remote farm pond on a long-abandoned piece of real estate, and now, decades after the pond was dug, it has become a favored breeding ground for spotted salamanders. We stood in the shallows, with a courting American woodcock adding to the ambience, and watched with mouths agape as dozens of salamanders swarmed in the water. Based on what we saw, and extrapolating for the size of the pond, we thought that as many as a few thousand spotted salamanders might be present.

The now aquatic creatures were in a frenzy of courting, depositing spermatophores, and laying eggs. The water was a bit murky, and we couldn't see clearly to the bottom, but it must have been an amphibious riot down there in the depths. Salamanders were shooting to the surface like corks, grabbing a quick gasp of air, and plunging back down to continue their manic activity.

A big spotted salamander glides by over the leaf-covered bottom of the pond. It was utterly remarkable to peer into the gloomy depths of this pond and see as many as twenty salamanders flashing by in the shallows. At times, the waters roiled with their activity. Such a congregation of salamanders is known as a congress. This congress is far more functional than the one in Washington, D.C., and at least in my estimation, more important.

Note the little pieces of what looks to be bits of white styrofoam. Those are spotted salamander spermatophores. The males deposit these little sperm-filled packets on the bottom of the vernal pool, and later a female will pick them up via her cloaca and thus fertilize her eggs.

The big globular jellylike masses of spotted salamander eggs are an impressive sight, and cause one to wonder how such a glob could come out of comparatively small amphibians. The opaque gelatinous matrix that surrounds the embryo quickly expands upon contact with water, so the eggs are actually far smaller than the fully expanded mass when they are expelled by the female salamander.

Predators galore go after amphibian eggs in vernal pools, and we saw ample evidence of this. I have some cool photos of some of these egg-eaters in action, and will share some of those later.

If all goes well, and the incredibly elaborate process of salamander reproduction, so fraught with perils, goes well, this is the end result. For a brief period, springtime vernal pools become writhing mass of amphibians participating in an eons-old ritual of replication.

StumbleUpon.com

4 comments:

A.L. Gibson said...

Great post, Jim! I was able to catch a nice migration of these that same Friday night down here in rural Athens county. Such remarkable creatures very few get the chance to see. Now, if only I could see some Jefferson and E. Tiger 'manders!

Jim McCormac said...

Thanks Andrew, and I'm glad that you caught some of the action, too. I'll be watching for a blog post, complete with your typically stunning images.

Buckeyeherper said...

Nice. They were moving a bit up here in MI as well, but I had other commitments. I miss springs in Adams Co though, you can see some other awesome species crossing the road too.

Andrew - Tigers are pretty tough down around Athens, but Jeffersons should be pretty doable. You can trip over them in Lake Hope for example.

Jason

Susan Nash said...

Loved this post! So descriptive, I felt like I was there. Thanks for all the cool info too.