Habitat selection by loons in southcentral Alaska

Three species of loons nest in the Matanuska-Susitna Valley, an area 80 km north of Anchorage in southcentral Alaska. This is a region of intense change; its human population doubled between 1980–1990 to almost 36000 people. The Alaska Department of Fish and Game through its Loon Watch Program has monitored 150 to 200 lakes since 1984, half of which are used by loons. Common loons (Gavia immer) nested on lakes of at least 12 ha while Pacific loons (G. pacifica) used lakes as small as 4 ha. Red-throated loons (G. stellata) were found on even smaller ponds. On all waters used by reproductive loons, 89% were connected to other water bodies, 62% of the shore was appropriate for nesting and 85% of the area was <15 ft (4.6 m) deep. This littoral zone comprised habitat for three-spined stickleback fish (Gasterosteus aculeatus), the dominant food source for loons, and supported large macrophyte beds that were used by loons as chick-rearing areas. The effect of human presence on summer loon distribution was dependent on the willingness of humans to accommodate to the needs of loons.