Wild Ideas: Wood frogs emerge with the urge to merge

Mar. 14, 2013
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When I sent out word recently that I was trying to find out if wood frogs had mated yet this winter, Rappahannock Nature Camp director Lyt Wood responded that he’d heard sporadic calling at his place, along the Hazel River, near the Shenandoah National Park boundary, but not the raucous clacking of this species in full mating mode.

From all reports, Cole Swindell Tickets wood frogs got a slow start here this winter. While they have a kind of antifreeze in their blood that enables them to mate as early as January, they need a few days of sustained thaw to do it, and such stretches have been scarce this year.

A wood frog (Lithobates sylvaticus), the earliest frog to breed each year in Virginia. They can breed a early as January, depending on the weather, but seem to have gotten a slow start in the Blue Ridge this year. Photo by Emilyk via Wikimedia Commons.

A wood frog (Lithobates sylvaticus), the earliest frog to breed each year in Virginia. They can breed a early as January, depending on the weather, but seem to have gotten a slow start in the Blue Ridge this year. Photo by Emilyk via Wikimedia Commons.

I was glad to get a call from Lyt, during the warm spell after the recent snowstorm, saying the frogs were in full chorus in his pond. They tend to congregate suddenly in vernal pools on warm days, breed in a frenzy when the weather is right and retreat back into the mud during cold spells. Once they’re finished breeding, they go back to the forest, where they live most of the year. Knowing this may be the only chance I’d have to see the breeding this year, I grabbed my camera and digital recorder and headed for Lyt’s.

Wood frogs in Rappahannock

It was quiet when I arrived. Lyt explained that a pair of red-tailed hawks that usually hung around when the frogs were breeding had shown up, and the frogs had dived for cover at the bottom of the pond. When wood frogs are in full breeding frenzy, they tend to be totally focused on the task, often with more than one male clinging to any female that comes to the show.

Lyt says he once had to rescue a female pickerel that blundered into the pond, only to be glommed onto by several wood-frog males. This intense focus leaves a great opening for predators. Lyt says he’s observed the hawks at his place stalking the frogs from the ground rather than dive bombing them from the sky but having little success when the frogs were not fully engaged in mating.

We walked down to a three-sided shelter that opens onto the pond, which was small, about 10 feet across and two feet deep. Lyt says he’s seen as many as 200 wood frogs at a time show up to breed in it some years. Lyt had just scared off the hawk pair, so we just needed to wait until the frogs felt safe enough to surface again. To make sure the skittish frogs reemerged, we stayed on the side of the shed opposite the open side, viewing the pond through an open window.

At least one female had made it to the pond at some point in the last week, since a large cluster of nearly clear egg clusters with small black dots in them lay along the surface. A cloudy white glob of red-spotted newt eggs was also clinging to some vegetation at the other side of the pond and quite a few newts were swimming around.

It took a while, but finally one male wood frog popped up and floated on the surface. Soon a few more appeared. Then one started clacking, and a couple dozen more popped up to join in. The clacking repeatedly got more intense, as if a female had shown up, but no females were in sight. I had this image of a singles bar on ladies’ night  – with no ladies. The excited males kept clambering over each other, only to be rebuffed by the object of their affection.

I recorded the males’ calling, but I couldn’t get close enough to photograph them with the rudimentary camera I have. When no females showed up after about an hour, I figured that maybe the expanse of open land they would have to cross from the nearby forest might be too daunting in daylight, so I decided come try another time and went home.

A couple days later Lyt emailed, writing that he had seen females creep in under the cover of darkness the night before and the frogs were now in a breeding frenzy. Once again I headed for his place. When I arrived, the males were in full chorus, and I could see some larger, lighter-colored females with them.

One female was on her back in the water, not moving, with at least three males attached to her. I tried to get close enough to get a picture, but my camera phone, which is all I had, was not up to the task. The males soon realized a potential predator was hovering, and finally let loose of the female and scattered. She continued to float for a few minutes, unmoving, before finally righting herself.

Newts were all over the frog eggs, fiercely tearing away the protective jelly-like substance that surrounded them to get at the embryos inside. Good thing there were lots of eggs – Lyt said there were more than he’d seen before in that small pool. Some of those are likely to come to fruition, morphing into tadpoles, then frogs, which would then venture off into the forest. Wood frogs are very faithful to their birth pools, so they’ll likely return to mate next year.

As I drove back over Lyt’s low-water bridge across the Hazel on my way home, spring peepers were in full chorus in the adjoining wetland. With “my” phoebes having shown up at home the day before, I felt spring had truly arrived.

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