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Showing posts with label four-toed salamander. Show all posts
Showing posts with label four-toed salamander. Show all posts

Tuesday, March 6, 2012

Egg-eating predators

The glassine waters of a vernal pool reflect the trunks of overshadowing trees, and mask the explosion of life under the surface. I was part of a group that visited this Adams County pool last Thursday.

While we saw plenty of critters on our diurnal Thursday expedition, the action was unbelievable on a nocturnal foray the following evening. I was out from 8 pm until midnight, roving about various amphibian breeding pools with John Howard and Tricia West. We visited several pools that were absolutely packed with salamanders and their eggs, as well as frog eggs. The dark-spotted billowing clouds in the photo are masses of wood frog, Lithobates sylvaticus, eggs. Excepting the Jefferson salamander, the wood frogs beat everyone to the punch and are among the first wave of amphibians to colonize the vernal pools, mate, and drop eggs.

Looking rather lovely, this little wood frog. They're tough; no other amphibian breeds as far north as do wood frogs, and they can virtually freeze solid, and recover to hop again another day.

This is an adult red-spotted newt, Notophthalmus viridescens. It is no friend of the wood frog, as we shall see. Newts are the most aquatic of our salamanders, and the adults live much of their lives in the water. The larval stage is termed a "red eft" (SEE HERE), and efts are terrestrial and highly mobile. Because of the efts' overland mobility, it is no mystery why newts can quickly colonize vernal pools.

A red-spotted newt floats just under the water's surface. It is gliding over huge masses of wood frog eggs, and for a newt, this situation is probably comparable to a kid with a sweet tooth living in a giant bowl of M & M's. Ditto that for the tiny strange-looking sharklike beasts in the backdrop. Those are the larvae of the marbled salamander, Ambystoma opacum.

Both newts and larval marbled salamanders are voracious predators of frog and salamander eggs. The pools that we examined were full of both species, eating their way through the jellied masses of amphibian spawn.

Tiny but deadly - at least if you're an egg - a larval marbled salamander floats over its meals. Marbled salamanders have an interesting reproductive strategy. The females lay their eggs under logs in vernal pools IN THE FALL, when all is normally dry. When rains finally strike, the wettened eggs hatch. Thus, by the time early spring rolls around and the rest of the amphibian crowd migrates to the vernal pools to drop eggs, the marbled salamander larvae are already there. And ready to plunder freshly laid eggs.

Between the egg-eating newts and marbled salamander larvae, scads of wood frog and other species' eggs are consumed. These predators are probably a factor that has led to the carpet-bombing strategy of egg laying for other vernal pool amphibians. If they can just produce enough eggs, some will survive the ravages of the predators.

Don't begrudge the marbled salamanders their eggs too much - they grow into the utterly spectacular amphibian shown here. I took this photo in fall a few years ago, in the very vernal pool shown in this post's first photo. John Howard took me there, as I had at that time never seen a marbled salamander and dearly wanted to. I was not disappointed.

This may be the smartest salamander breeding in the vernal pool. It is a four-toed salamander, Hemidactylium scutatum, and it's also our smallest species of salamander. Four-toeds stay out of the water, and lay their eggs under loose carpets of moss that drape moist logs that lay about the vernal pool. Thus, its eggs are not vulnerable to the predations of newts, marbled salamander larvae, and whatever other predators lurk in the waters. For a more detailed account of four-toed salamanders, CLICK HERE.

Wednesday, March 16, 2011

The running of the salamanders

A cold American Toad creeps across the asphalt of a rural western Ohio road. Finally, last night I escaped to the great rainy outdoors to have a go at salamandering. We've already had some good nights - reasonably warm and rainy - and I'm sure that many of our amphibians have already made their way to the vernal pools to mate and release their spawn.

As I'm sure most of the sophisticated readers of this blog know, come the first warm wet nights of very early spring, amphibians move en masse overland to breeding pools. To me, catching these slimy creep-crawlies in the act is a pleasurable rite of spring. And we scored last night, but not in a very major way. It was wet enough, with thoroughly saturated ground and intermittent drizzle all evening. A bit on the cool side at 45 degrees, but well within the operating conditions of our salamanders and other amphibians.

But there wasn't much to see in tried and true amphibian hotspots, and the relatively few animals that I did find came out late; around 10:30 pm. By then, the bewitching hour was drawing near, as I had to get up and go to work today. But some finds were made...

Always a surefire crowd-pleaser, a Spotted Salamander, Ambystoma maculatum, hightails it across the road. This site sports wooded vernal pools on either side of the road, and fortunately for our viscous friends, vehicular traffic is light. Nonetheless, I always find plenty of roadkill on these forays, and that's sad. Bisecting high-quality salamander habitat with roads is an insidious impact that results in sometimes enormous mortality of salamanders and other amphibians. Depending on traffic volume, I suspect that over time entire salamander populations are destroyed by repeated carnage year after year.

This Spotted Salamander was a big boy; about as large as they come. Spotteds are in the genus Ambystoma: the fabled mole salamanders. For most of the year, they dwell subterraneously, pushing through the damp soil and feeding on various invertebrates. When triggered by various cues in early spring, most mole salamander species burst from the soil and take up an overland march to ancestral breeding pools. Catch it just right and hit a prime spot, and you might find hundreds if you're willing to brave dark, rainy and cool conditions.

An odd duck, this gal. It is a so-called "unisexual" salamander and the area where I photographed her has many. This animal and her ilk are the product of longtime hybridization between several species of mole salamanders. The parentage involves Blue-spotted Salamander, Ambystoma laterale, Smallmouth Salamander, A. texanum, Jefferson Salamander, A. jeffersonianum, and sometimes Tiger Salamander, A. tigrinum.

Almost all if not all unisexuals are female, and individuals have extra sets of chromosomes. The genetic makeup of these beasts varies wildly, as does their appearance. This individual is particularly well markedwith porcelain-blue flecking on its sides, a sure sign of Blue-spotted Salamander genes. I'm guessing that Smallmouth genes are present, too, and who knows what else.

How these things reproduce and carry on is not well understood. I've seen their egg masses, and nearly all of the eggs appear to be only partially developed. Apparently some of them must be fertile and hatch, though. Somehow the unisexual saamander manages to pick up the sperm of fertile "pure" males of one of the species that I mentioned above. I don't pretend to understand the unisexual salamander phenomenon; if you do, feel free to comment and enlighten.

Weird stuff. Well, unisexual or not, mole salamanders are things of great beauty and interest and seeing them is always a treat. Friday night is looking like conditions could be good for another run, and if it is I'll probably be bck out and looking for the mammoth Tiger Salamanders.

Tuesday, April 6, 2010

Four-toed Salamander

A beautiful vernal pool in Delaware County, Ohio. These wetland are quite alluring to salamander-seekers. I was fortunate in that Lauren Blyth, a died-in-the-wool salamander enthusiast, took me to see a couple of excellent and out-of-the-way vernal pools the other day. Our primary target? The odd, uncommon, and local Four-toed Salamander, Hemidactylium scutatum.

Vernal pools are wooded wetlands, typically rather small, and at their soggiest in spring. By mid to late summer they often lose all of their standing water. But spring is when most of the amphibians breed, and a number of species of frogs and salamanders gather in vernal pools to mate, lay eggs, and make more of their kind.

Four-toed Salamanders are probably the hardest of the vernal pool salamanders to find, and to successfully ferret them out requires some knowledge of their habitats and a lot of careful searching. They make their nests under moss on damp logs in the water; the moss-cloaked log above is a perfect example of this specialized breeding habitat.

Our quarry, a beautiful adult Four-toed Salamander. All of our other species have five toes on the rear feet; this one has but four as you may have guessed. It is not a large salamander, taping out at perhaps three inches on average.

If you are uncertain of the identification of a 4-toe, just turn it over. They are painted bold white below, and prominently speckled with blackish flecking. No other of our species looks anything like this on the ventral surface.

Nest with eggs. The female can be seen interwined with eggs in the upper right - she remains to guard them until they hatch, which takes about six weeks. More eggs can be seen on the left. The eggs aren't small, and it is amazing all of these come from her tiny body. Four-toed Salamanders are rather finicky about site selection, preferring older sheets of moss - the species of moss doesn't seem that important - that form loose drapes. The moss should also be directly over the water, so that when the tiny larvae hatch, they can drop directly into the water and thus probably greatly increase their odds of survival.

Researchers seeking this species need to be very cautious in their approach. Tearing around and ripping the moss off the logs is NOT the way to go about hunting four-toes. You might find some, but will also probably cause the failure of the nest. Rather, it is best to carefully inspect logs that appear suitable and gently tug the moss to see if it is loose. If so, slowly and gently peel it back and see if anyone is home. Lauren is very good at this, and she located five nests, and we didn't spook any of the salamanders. After we documented their occurrence the moss was folded back over the nest and all was well.

Four-toed Salamander, one of our most secretive amphibians. Given a good look, they are quite the charmers, though, and sport an interesting pattern of colors. They also typify the hidden but fascinating world of vernal pools, one of our most valuable wetland types.