Picture Id: 391983
INTRODUCTION: Since 1983 inexplicably large numbers of dead and dying common l oons (Gavia immer) have been found along Florida's Gulf Coast. Under threat fr om acid rain, lake pollution, and human encroachment, their numbers are declini ng elsewhere as well. Lake acidification has resulted in fewer fish, the birds' principal f ood. More insidiously, it increases the rate at which mercury in ponds is toxi fied; the poisonous methylmercury enters the food chain and is eventually inges ted by the loon. It attacks the bird's nervous system, hindering its ability to feed and reproduce. ----- LEGEND: A loon in breeding colors incubates its eggs in its n est among the reeds close to the shore of a lake or pond. Devoted parents, mal e and female loons share incubation duties for some 28 days before the chicks hatch. Occasio nally loons will doggedly -- and indefinitely -- attempt to hatch a foreign obj ect, such as a seashell or an egg-shaped rock.
MICHAEL S. QUINTON/National Geographic Creative