Vernal Pool Showing Signs of LIfe

Vernal pools are seasonal bodies of water overlooked by many. They are essentially wooded swamps or puddles in the forest fed by snow melt and spring rains. To a conservationist and amphibian enthusiast like myself, a vernal pool is like a hidden gem. We are lucky enough to have a vernal pool within walking distance of my classroom and my second semester wildlife students will soon begin to learn about these critical pieces of habitat first hand out in the field. I have been using a game camera to monitor our newly installed wood duck box in one of the nearby vernal pools since its installation in February. In that time, we have gotten images of a gray fox and raccoon scurrying across the ice near the nesting box but since our recent thaw, the images have tapered off.

A raccoon crosses the frozen vernal pool earlier this month. 

The camera was originally placed in this location in an effort to capture wood ducks in the vernal pool possibly entering/exiting their newly installed nesting box. While there has been no such luck yet, we received some bonus images and video over the weekend. Gusty winds last Friday afternoon triggered the camera and wood frogs (Rana sylvatica) can be seen floating in the water below the nesting box. Wood frogs are one of the first amphibians to emerge from dormancy in the spring. Shortly after waking up, they travel to the same vernal pool that they emerged from to produce the next generation. They leave tennis ball sized egg masses containing hundreds of eggs attached to sticks and vegetation in the pool before heading back to the forest where they will spend the rest of the year (hence the name "wood frog"). The individuals shown in the video below are most likely males that have shown up early due to last weeks warmth. I got reports of male wood frogs calling from this vernal pool as early as 3/14 and witnessed the "duck like chuckle" of a wood frog chorus at this site personally on the afternoon of 3/16. There are a handful of egg masses now in the pool but it is obvious that few females have shown up at the pool thus far. They are typically a week or so late to the party. In the mean time, the males float around the center of the pool calling and defending their small piece of the puddle in a behavior known as lekking. 

Look closely in the water below the nesting box to spot the wood frogs.

Today's spring snowstorm is sure to put a delay on the breeding activity at our vernal pool. Being ectothermic (cold blooded), a wood frog's body temperature is reliant upon its surroundings and they are only active at temperatures in the upper 40s or beyond. In classic Maine fashion, just as the warmth of spring seems fully upon us, mother nature has other ideas. The wood frogs that have already arrived at the vernal pool will most likely re-enter dormancy and await the next warm up to resume their breeding activity. 

Conditions this morning at the vernal pool.