Valley, P.J. 1985. Common loon (Gavia immer) density, productivity, and nesting requirements on the whitefish chain of lakes in north-central Minnesota. Final report (senior thesis) submitted to the Nongame Wildlife Program, Minnesota Department of Natural Resources. 37 pp.
From 15 April to 25 August 1985, a field study of the common loon (Gavia immer) was conducted on the Whitefish Chain of Lakes in north-central Minnesota. The primary objectives of this study were to determine common loon densities on the ten lakes in the study area, inventory loon breeding pairs, and monitor their productivity. In conjunction with these principal activities, habitat characteristics and other factors which may affect common loon nest location and success were evaluated; and loon behaviors such as courtship, nest building, incubation, parental care of chicks, feeding and intra- and interspecific associations were observed.
A total of 49-56 loons (2.7 - 3.1 loons/mile2) were located, including 19 breeding pairs, 2-4 non-breeding pairs, 5-8 single loons, and 2 loons in immature plumage. Nineteen chicks were hatched to 12 breeding pairs, 16 of which successfully fledged. Loon nests were commonly protected from the wind and waves, and were located away from direct human impact. Loons preferred to nest on deeper and larger lakes, or more significantly, on lakes of longer shorelengths. Those that nested in less disturbed areas had significantly higher hatching success than those in more disturbed areas, and hatching success for two-egg clutches was significantly greater than that of one-egg clutches.