title: Intraguild predation and competition impacts on a subordinate predator.
abstract: Intraguild (IG) predation and interspecific competition may affect the settlement and success of species in their habitats. Using data on forest-dwelling hawks from Finland, we addressed the impact of an IG predator, the northern goshawk Accipiter gentilis (goshawk), on the breeding of an IG prey, the common buzzard Buteo buteo. We hypothesized that the subordinate common buzzard avoids breeding in the proximity of goshawks and that interspecific competitors, mainly Strix owls, may also disturb common buzzards by competing for nests and food. Our results show that common buzzards more frequently occupied territories with a low IG predation threat and with no interspecific competitors. We also observed that common buzzards avoided territories with high levels of grouse, the main food of goshawks, possibly due to a risk of IG predation since abundant grouse can attract goshawks. High levels of small rodents attracted interspecific competitors to common buzzard territories and created a situation where there was not only an abundance of food but also an abundance of competitors for the food. These results suggest interplay between top-down and bottom-up processes which influence the interactions between avian predator species. We conclude that the common buzzard needs to balance the risks of IG predation and interference competition with the availability of its own resources. The presence of other predators associated with high food levels may impede a subordinate predator taking full advantage of the available food. Based on our results, it appears that interspecific interactions with dominant predators have the potential to influence the distribution pattern of subordinate predators.
authors: Finnish Museum of Natural History Luomus, University of Helsinki, P.O. Box 17, 00014, University of Helsinki, Helsinki, Finland. heidi.bjorklund@helsinki.fi.|Department of Biosciences, University of Helsinki, P.O. Box 65, 00014, University of Helsinki, Helsinki, Finland. heidi.bjorklund@helsinki.fi.
authors: Heidi
authors: H
authors: Björklund
authors: Finnish Museum of Natural History Luomus, University of Helsinki, P.O. Box 17, 00014, University of Helsinki, Helsinki, Finland.|Department of Biosciences, University of Helsinki, P.O. Box 65, 00014, University of Helsinki, Helsinki, Finland.
authors: Andrea
authors: A
authors: Santangeli
authors: Department of Biosciences, University of Helsinki, P.O. Box 65, 00014, University of Helsinki, Helsinki, Finland.|Department of Mathematics and Statistics, McMaster University, 1280 Main Street West, Hamilton, ON, L8S 4K1, Canada.
authors: F Guillaume
authors: FG
authors: Blanchet
authors: Suonenjoki Research Unit, Natural Resources Institute Finland, Juntintie 154, 77600, Suonenjoki, Finland.
authors: Otso
authors: O
authors: Huitu
authors: Suomen metsäkeskus, Itäinen palvelualue, Pohjois-Karjala, Poikolantie 2, 83900, Juuka, Finland.
authors: Hannu
authors: H
authors: Lehtoranta
authors: Natural Resources Institute Finland, P.O. Box 2, 00791, Helsinki, Finland.
authors: Harto
authors: H
authors: Lindén
authors: Finnish Museum of Natural History Luomus, University of Helsinki, P.O. Box 17, 00014, University of Helsinki, Helsinki, Finland.
authors: Jari
authors: J
authors: Valkama
authors: Department of Biology, University of Turku, 20014, Turku, Finland.
authors: Toni
authors: T
authors: Laaksonen
mesh_terms: D000818:Animals; D003163:Competitive Behavior; D005387:Finland; D020387:Food Chain; D065928:Forests; D046428:Hawks / Q000502:physiology*; D011235:Predatory Behavior; D013045:Species Specificity; D020305:Strigiformes / Q000502:physiology*
keywords: Bird-of-prey; Dominance; Food conflict; Interference competition; Predator avoidance