Taking a Tern on the Dance Floor

While fly fishing from a float tube in the early 1990s on East Dollar Lake, located north of Valleyview, Alberta, I was fortunate enough to witness two connected events on a massive scale, covering almost the entire surface of this pothole lake. A massive hatch of damselflies, numbering in the thousands, were springing from the lake surface. Evidence of rainbow trout pursuing and catching these damsels could be seen by the energetic splashes and boils in the water. Over the course of a few minutes, one species of bird, the Black Tern, in a flock numbering about one hundred, began their chase of these protein loaded life forms. Terns swooped and hovered and gobbled up the newborn hatch. Nature in this magnificent moment, shared the meeting of the tern and the damselflies.
In looking at the delicate beauty of this seabird, one notices the long, pointed wings, thin, pointed bill the shallow forked tail, all standing on short legs. The breeding plumage of adults is eye-catching. The head and underparts are black, while feathers are dark grey above, combined with pale grey under-wings and under-tail. Weighing just 60 grams (2 ounces), the Black Tern moves like a whisper in the wind. Be it at East Dollar Lake or Frank Lake, to watch this species forage for food, is much like imagining an angel perched on a cloud. Flying slowly with grace, the tern will at times, dip into the water’s surface to nab minnows, water-bound insects or snag insects in flight. Unlike common terns that at times crash into the water to catch its prey, it’s that delicate aerial manoeuvring of the Black Tern that holds ones gaze.
Habitat is key to attracting colonies of Black Terns to locations like Frank Lake. Desiring dense, marshy wetlands and at times using the edges of shallow lakes, this environment provides a potpourri of insect life and often minnows to provide food during their stay in Alberta. Ideal nesting locations are hidden within the marsh reeds and on floating vegetation well away from shore. Muskrat platforms or lodges are used as nesting sites if available.
As Frank Lake, east of High River, decreases in depth over the spring and summer months, the best place to enjoy watching these terns are along the new growths of reeds and cattails, where the water may be but a few centimetres deep. The “dance” of the tern seems to follow the line along the cattail edges, followed by a hover and dive to the surface with the catch of insect or minnow in a millisecond, and then on to the next cattail.
Not unlike other birds, the Black Tern population has declined by over half since 1966, with a current North American population estimate of 250,000. The disappearance of wetlands, pesticides killing insect life, poor water quality and the loss of prey fish in wintering areas, all contribute to this decline.
I fondly recall those minutes on East Dollar Lake the Black Terns and damselflies shared. The cycle of life, that intricate relationship between bird, water, insect and earth, all energized by the sun, is something we carbon based units can take time to appreciate.