Estimating Prairie Falcon and Golden Eagle Nesting Populations in North Dakota

Publication Type:Journal Article
Year of Publication:1987
Authors:Allen, GT
Journal:The Journal of Wildlife Management
Date Published:1987
ISBN Number:0022541X
Keywords:Accipitridae, Aquila, Aquila chrysaetos, Falco, Falco mexicanus, Falconidae
Abstract:Stratified random sampling of $23.3-\text{km}^{2}$ units was used in 1983 and 1984 to estimate the nesting populations of prairie falcons (Falco mexicanus) and golden eagles (Aquila chrysaetos) in western North Dakota. Based on independent estimates from the 2 years, the nesting population estimates and 95% confidence intervals were 107 ± 94 pairs of prairie falcons and 95 ± 79 pairs of golden eagles. Biases in surveys for prairie falcons were assessed in 1984. No differences were found between 1st and 2nd aerie visits in the number of adult prairie falcons present at occupied sites or in their response distances. There was no seasonal trend in response distances of adults. Up to 22% of all occupied aeries might not be seen during a single ground survey. Nesting failures and lack of responses to observers reduced survey accuracy. To account for bias, the prairie falcon population estimate was adjusted to 125 ± 94 pairs. Alternative survey methods probably could increase the precision of the estimates.
Short Title:The Journal of Wildlife Management
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