The Status and Distribution of the Common Loon in Wisconsin

Abstract

An investigation to determine the status and distribution of the common loon (Gavia immer) in Wisconsin was conducted during the summers of 1976 and 1977. Aerial survey methods were 90 percent accurate in assessing loon populations. Audio stimulation was used to attract loons for census purposes. The estimated Wisconsin loon population is 1300 adults and 258 juveniles. Loon distributions were primarily restricted to the northern one-third of Wisconsin. Average size of 195 broods was 1.41 young per brood. Three broods, consisting of three young were observed. Forty percent of the observed adult loons were successful breeders. Loon populations appear stationary in Wisconsin, but continued human disturbance could lead to a future decline. The desertion of three loon nests was linked to human disturbance. Direct human disturbance (harassment and boating activities) is more detrimental to successful breeding than human presence. The number of dwellings per acre of water area of lakes with loon populations was significantly lower (P<0.05) than lakes without loons. While loons showed preferences for certain habitat types (large lakes, deep water, and a neutral pH), they do tolerate different types of water areas.