Thursday, May 6, 2010

The Prairie Tern

Most birders remember their first year of "hunting" for new species with a special fondness. Every discovery was exhilarating and the growing list of observations produced a sense of accomplishment. Over the years, having seen these same birds on numerous occasions, the repeat encounters lose their luster and we constantly search for new quarry. But, for many of us, there are some species that occupy a special place in our birding memory and each sighting takes us back to that first discovery; in my case, black terns are on that list.

I first observed a flock of black terns at the Murray Dam on the Arkansas River, just northwest of Little Rock; according to my oldest field guide, it was May 16, 1980. Since these birds winter along the coasts of Central and South America and since I have never travelled to their favored breeding grounds on the vast prairies of central Canada and the north-central U.S., I have rarely encountered these birds since that first sighting. In fact, I have only seen two other flocks over the years, one in northeastern Colorado and the other in central Kansas.

Favoring prairie wetlands, these small, graceful birds arrive on their breeding grounds in mid-late May and begin to nest; three eggs are typically laid on floating vegetation, on abandoned muskrat mounds or in cattails along the marshy shores. Remaining in loose colonies through the breeding season, black terns feed primarily on insects but also pick small fish and crustaceans from the surface of lakes and ponds. In late July, they begin to congregate at favored staging areas and depart for their wintering sites by early September; hopefully, in the near future, I will visit them during their brief summer on the prairie.