Effects of watercraft on bald eagles nesting in Voyageurs National Park, Minnesota
Grubb TG, Robinson WL, Bowerman WW. 2002. Effects of watercraft on bald eagles nesting in Voyageurs National Park, Minnesota. Wildlife Society Bulletin. 30(1):156-161
Some activities of humans near bald eagle nests during the breeding season have been related to reduced nesting success. We evaluated effects of watercraft on nesting bald eagles in Voyageurs National Park, Minnesota, by observing eagles attending 9 active nests in 1995 and 1996. In 515.8 hours of observation, 2,431 watercraft passed within 800 m of these nests. Eagles responded by showing alert posture or flying 115 times for a 4.7% response frequency. Frequency of response varied between 2.4 and 16.7% among nesting pairs of eagles and showed a curvilinear relationship with mean number of watercraft per hour. A classification and regression tree model (CART) was used to explore and quantify conditions leading to bald eagle response, despite the species' low overall response rate. The model indicated that distance was the most critical component of any potential watercraft disturbance, with responses decreasing at distances of <85 m. Duration, number of watercraft/event, and time of day also affected eagle response rates beyond 85 m. Overall accuracy for the CART model was 0.65, indicating that response to watercraft will be predicted correctly 2 times out of 3. (authors' abstract)
- Type
- Journal Article
- Authors
- Grubb, Teryl; Robinson, William; Bowerman, William
- Units
- VOYA
- Keywords
- Bald Eagle (Haliaeetus leucocephalus), Boating, Disturbance, Human Impact, management decisions, Minnesota, Nesting, recreation impacts, Voyageurs National Park