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Competitive interactions among raptors in boreal forests
Harri Hakkarainen1, Sakari Mykrä, Sami Kurki
1Section of Ecology, Department of Biology, University of Turku, 20014 Turku, Finland. harhak@utu.fi
Oecologia
|September 18, 2004
Summary
Large goshawks (Accipiter gentilis) often take over nests from common buzzards (Buteo buteo) and honey buzzards (Pernis apivorus) in Finland. This competition negatively impacts common buzzard breeding success and territory occupancy.
Area of Science:
- Ornithology
- Behavioral Ecology
- Conservation Biology
Background:
- Interspecific competition among raptors is crucial for understanding avian population dynamics.
- Large forest-dwelling raptors may displace smaller species from optimal nesting sites.
Purpose of the Study:
- To investigate interspecific interactions and competition among goshawks, common buzzards, and honey buzzards in boreal forests.
- To determine the impact of goshawk presence on the breeding success and territory use of common buzzards and honey buzzards.
Main Methods:
- Field observations of nesting raptors in western Finland from 1983 to 1996.
- Analysis of territory occupancy and fledgling production in relation to species presence and proximity.
Main Results:
- Over half of new goshawk territories were previously occupied by common buzzards or honey buzzards.
- Common buzzard fledgling production decreased by 20% near goshawk nests, and their subsequent territory occupancy was reduced.
- Honey buzzard fledgling production was not significantly affected by goshawks, likely due to staggered breeding seasons.
Conclusions:
- Goshawks exert significant competitive pressure on common buzzards, particularly for nesting resources.
- Habitat overlap and the energetic cost of nest building favor larger raptors like goshawks in competitive interactions.
- Conservation strategies for forest-dwelling raptors may need to consider interspecific competition, especially in areas with limited nesting sites.