Thursday, March 13, 2014

Braving the Bitter Cold for the American Bittern

On my birthday, in mid-December, I dragged my entire family -- parents, husband, and 4-year-old son -- to find an American Bittern. We drove to Prairie Ridge Ecostation in Raleigh, NC, following a trail of eBird and list-serv sightings of this bulky brown and tan bird in the Heron family (Ardeidae).

On a crisp, clear winter's day, we slowly walked around one cattail fringed pond, stopping every so often to carefully eye the reeds. We knew that the American Bittern was a camouflage expert: its brown and tan vertical stripes help it fade into the winter-bleached cattails just as much as its awkward stance, with its long beak pointed into the air. The first pond yield no bittern. We walked on to the next. Eventually, fingers chilled and faces frozens, we walked back across the stark field to our car, heads hung with the weight of failure.

Over a month later, I saw another posting about the American Bittern at Prairie Ridge Ecostation. Again, I dragged my family back out. This trip ended in failure too. I was devasted because I knew the bittern wouldn't stick around much longer. American Bitterns will spend the winter in much of North Carolina, feeding on crayfish and frogs without having to bore through a thick layer of ice. But in spring, the American Bitterns leave North Carolina, and head to their breeding grounds in the northern United States and Canada. Lamenting another lost opportunity, we ate away our sorrows at the local Ben and Jerry's.

Yesterday, I saw another posting about the American Bittern. A lady, much like me, had visited the site three times before finally seeing it. I decided to drag my family out to Prairie Ridge Ecostation one last time. As we walked around the first pond, my heart began to sink. Nothing. We headed to the smaller, cattail-filled pond. We walked halfway around this little pond when I saw a strange bit of dark brown mixed into the pale cattails, my eyes finally focused in on the elusive American Bittern.

At first it seemed frozen in its strange beak-up pose. Then it was comfortable preening in front of us, and the bittern even ate a little something it grabbed out of the shallow pond. The bittern moved with great speed and precision, each movement efficient and graceful.

I had finally found the American Bittern at Prairie Ridge. And I even got to take it home with me. When we discovered the bittern, my son magically transformed himself from a little boy uninterested in birds into a keen mimic of the American Bittern. Later he told me that "the bird" was the most beautiful thing that he had seen today.

Tuesday, March 4, 2014

Eastern Garter Snakes: Mating Balls & Sex in the Trees

Last week, Duke Forest staff photographed Eastern Garter Snakes (Thamnophis sirtalis sirtalis) intertwined on the forest floor. They had a discovered a "mating ball" of small males vying for the chance to fertilize a mature female.

Eastern Garter Snakes mating in the Duke Forest, February 20, 2014; Photo courtesy of Sara Childs.

Other garter snake species are better known for their mating balls, including the Red-Sided Garter Snake (Thamnophis sirtalis parietalis). In Manitoba, as many as 25 male Red-Sided Garter Snakes will compete for the chance to fertlize one female, with hundreds of snakes congregating in spring outside their hibernacula or winter dens. The females release a pheromone that drives male Garter Snakes wild (video link here).

Both Eastern Garter Snakes and Red-Sided Garter Snakes have been documented to mate in the trees, a full yard off the ground. Researchers believe that Garter Snakes are driven to arboreal mating by their thermoregulatory needs -- it's easier to make sweet snake love while warm. Typically, Garter Snakes are only seen mating in trees after a rain. The rain cools the ground, but the trees and shrubs remain warmer at air temperature. On sunny days, the ground tends to be warmer than trees, and Garter Snakes are more likely to be seen mating there.