Ohio Birds and Biodiversity: vernal pool

Showing posts with label vernal pool. 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.

Friday, March 18, 2011

Wood Frog

A beautiful vernal pool on the floodplain of Little Beaver Creek in Columbiana County. I made a five mile float down the river today wth some colleagues, in search of one of Ohio's rarest breeding birds. We found the goosanders, and more on that in a later post.

At one of our stops, we heard the distinctive quacking clucks of Wood Frogs, Lithobates sylvatica, and entered the forest to investigate.

Two small woodland pools were filled with riotous Wood Frogs in full courtship mode. Their collective clucks, at a distance, always remind me of a far off pack of crows whooping it up.

Wood Frogs may be tiny, but they're loud, and very, very tough. No frog ranges further north than does this species, and they can survive being frozen solid. For a very brief period in early spring, wood frogs enter vernal breeding pools to meet, mate, and deposit eggs. Their noisy courtship antics are about as good a harbinger of spring as anything, and we spent quite some time admiring the frogs.

The females had already begun to deposit their impossibly massive egg clusters. These masses expand considerably as the eggs uptake water; it isn't as if they come right out of the female frog at this scale.

Fresh Wood Frog spawn, up close. In about a month, these eggs will hatch tiny tadpoles, and another two months after that, the tadpoles will metamorphosize into little Wood Frogs and complete the cycle.

Above is a brief video that I made while standing in the vernal pool, surrounded by quacking Wood Frogs. When a person nears a pool full of active frogs, they'll all suddenly clam up and drop to the bottom. The trick is to carefully wade in, and then stand motionless for five minutes or so. After a bit, the frogs bob back to the surface and begin calling, mating, and going on with their frenzied business. It's quite a spectacle.

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.

Thursday, March 12, 2009

Salamanders, Newts, and Unisexuals

Last Tuesday night was good for hunting salamanders - not great, but good. A crew of us dispatched to the meadows and swampy woods of Logan County, near Bellefontaine (beautiful fountain, in French), and found more than enough to occupy our interest. We had hoped hard for rain - about the only time I ever do - and it came, but not until 1 am. Rain lubricates the landscape, and creates much better conditions for salamanders making the overland journey to breeding pools. A long night, I didn't get back home until 4 am, but well worthwhile.

Some of the amphibious crew emerges from a wetland, late at night. L to R: Greg Lipps (more on him in a sec); Chip Gross, an outdoor writer who was gathering material for an upcoming story for Country Living Magazine; and videographer/narrator extraordinaire Skip Trask, who films for Wild Ohio TV.

Mr. Salamander, Greg Lipps, panning for amphibious gold: Tiger Salamanders. Greg is a phenom - one of the most knowledgeable herpetologists in the Midwest, a field dynamo, generous with his knowledge, and full of irrepressible energy. We were fortunate to have him along this night. This blog entry is all about salamanders, but Greg pulled another kind of spectacular beast out of one of the wetlands we visited, and I'm going to blog that separately, later.

Our host, and an exceptional all-around naturalist, Troy Shively. Troy grew up in Logan County and knows its every nook and cranny. He led us to some great spots for the wriggly ones.

Presto! As if by magic, these mini-dragons appear above ground for a few days each spring, seek breeding pools, mate and lay eggs, and vanish back into the earth. This is our largest salamander, the Tiger Salamander, Ambystoma tigrinum. It was the A-list salamander for the eve, the one we really hoped to find. And we did, maybe a dozen or so.

Here, your wet wind-tousled and tired blogger holds a Tiger Salamander to create a size scale. Some jumbos can reach a foot in length! Tigers seem to be associated with Ohio's former prairie regions, and they prefer much more open landscapes than other species. Some individuals are boldly marked with yellow dots and smudges; most of the ones that we caught this night were rather dull.

Tiger Salamander, heading into a breeding pool. As if pulled by a magnet, they forge over, through, and around obstacles in their quest to reach the ponds and reproduce. Tigers prefer deeper water than their allies, and this pond was probably a good four feet deep in the center. We were able to spot the giants under the clear water as they hung in the water column, rested on the bottom, or darted rapidly about, fishlike.

Troy led us to a spectacular road that bisected wet woods dotted with vernal pools. Late in the night, after the rain began, we saw many salamanders crossing the roadway. This Spotted Salamander, Ambystoma maculatum, was in one of the nearby woodland pools. I'll never tire of seeing these.

We saw many Red-spotted Newts, Notophthalmus viridescens, both in the pools and crossing the road, as this one is doing. The critter above is known as a Red Eft, which is the larval, terrestrial stage of the newt. Efts might live up to three years away from water, boldly roaming the forest floor. Forgive me the anthropomorphism, but they really are "bold". It isn't uncommon to see efts wandering about during the day, especially after a shower. Not much will mess with them - efts are quite poisonous. Allegedly, there is a case of a college student dying after efts were foolishly substituted for goldfish in that age-old bit of frat boy foolishness, the goldfish-eating contest.

When the newt matures, it returns to the water and becomes strictly aquatic, and might live for several more years.

Now we come to the unisexual part. You may have been wondering about that. Well, I was talking about this beast - an odd and poorly understood "species". We saw plenty of them, and all appeared to be part of a hybrid swarm that produces all female populations of these curious animals. There are probably three parental species involved: Blue-spotted Salamander, Ambystoma laterale; Smallmouth Salamander, A. texanum; and Jefferson Salamander, A. jeffersonianum. The blue flecking, characteristic of Blue-spotted, is evident on this individual, and many showed strong traits of Smallmouths.

Greg is actively working on this mystery, and took genetic material from a number of the individuals that we encountered. Much work remains to ferret out the answers to this puzzle. Whatever they may be, they're still cool to find, and exceptionally entertaining. This one found me troubling, and paused, rearing its neck up, cobra-like. Check the following video out for a very cool unisexual display.

As you will note, "Video Magic" wants me to buy their product. Maybe I will; they did a good job of compressing this vid down enough so that Blogger would load it. The video shows a unisexual salamander crossing the road, and us agitating it so that the animal would perform its fascinating defense display. When threatened, they sometimes raise their tail and wave it hypnotically, as a lure to the predator. The idea is that the coon or whatever will key in on the tail, and grab that rather than the body and all of the vital organs. When it does, the tail or parts thereof snap off, and Mr. Coon gets a slimy eel-like mouthful of some of the most godawful viscous gunky-tasting junk imaginable. He'll not want to visit that party again, and our salamander escapes, sans tail, which it may partially regenerate.

Lots of strange stuff in the realm of salamanders.

Salamander Hunting

Tis the season, for those of an amphibious bent. The salamanders are running. In an age-old ritual of early spring, these largely subterranean dwellers emerge with the first warm rains, and make their wriggly peregrinations overland to breeding pools. There, they meet, greet, do some other things, and then deposit egg masses.

Hit it right, and you'll find plenty of salamander action, and if you've not done a nocturnal salamander hunt before, well, you don't know what you're missing.

Night before last was awesome, and I got some really good images of some spectacular beasts, and some decent vid, too. I'll slap some of that up here soon, but first, a few shots from last Saturday night in Adams County.

Some of us were the recipients of Steve and Marian Moeckel's hospitality, and visited their new digs back up in a rural hollow. A small intermittent stream, strewn with rocks, courses right by the cabin, and we did a bit of rock-flipping out there. Bingo! Several beautiful Southern Two-lined Salamanders, Eurycea cirrigera, were uncovered. These are surprisingly common, but one must check under streamside rocks to find them. We also have the practically identical Northern Two-lined Salamander, E. bislineata, in Ohio. The latter is found in the northern half of the state, roughly; in southern reaches it is the above species.

Another very cool little wriggler inhabiting the Moeckel's stream was this, the Northern Ravine Salamander, what we used to call Plethodon richmondi. Greg Lipps tells me the scientific name has been changed to Plethodon electromorphus, as genetic work has revealed this one to be distinct from more southerly Ravines. These Northern types were split from Southern types, and this one was named for laboratory processes that resulted in the split. Whatever, it is a handsome little animal, very long and attenuate.

Note the length of the tail in comparison to the total length, and those tiny little legs. Quick little buggers, though, when they want to be.

Later, after darkness settled, bats were on the wing and the woodcock were twittering and peenting, we set out to find some mole salamanders. These are well-named: salamanders in the genus Ambystoma live 99% of their lives under the ground, emerging only briefly to court, mate, and reproduce in vernal pools. This is a Spotted Salamander, Ambystoma maculatum, one of the most striking amphibians in the United States and a species utterly dependent upon healthy woodland vernal pools.

Eye level with the Spotted Salamander, in an Adams County vernal pool. They are pretty good sized, with some whoppers taping out at over seven inches.

Rather a Plain Jane, this one. It's a Jefferson Salamander, Ambystoma jeffersonianum. They are often our most common mole salamander in the areas in which they occur, and are part of a maddening hybrid complex. More on that later - I saw plenty of these crosses the other night and have good photos and video that I'll share later.

This species is named for Jefferson College in Pennsylvania. The college was named for an accomplished early naturalist who we've probably all heard of, Thomas Jefferson. Thus, in a roundabout way this subsurface earthworm-eater commemorates one of our greatest presidents.

Jefferson Salamander larva. This is the earliest of the mole salamanders to make their way to the breeding pools, often when it is still cold enough to crust pond edges with ice. Thus, they also get the jump on the other species, and the Jefferson larva precede the others. This small pool was full of them. In short order I saw a hundred or more. Note the feathery gills behind the head. They'll live in the pool until about early July, at which point the young salamanders will assume the subterranean life os the adults. It's vital that fishless pools are available, as most fish are voracious predators that would make quick work of these salamander fry.