A1 Vertaisarvioitu alkuperäisartikkeli tieteellisessä lehdessä
Fear in farmlands: how much does predator avoidance affect bird community structure?
Tekijät: Norrdahl K, Korpimaki E
Kustantaja: MUNKSGAARD INT PUBL LTD
Julkaisuvuosi: 1998
Journal: Journal of Avian Biology
Tietokannassa oleva lehden nimi: JOURNAL OF AVIAN BIOLOGY
Lehden akronyymi: J AVIAN BIOL
Vuosikerta: 29
Numero: 1
Aloitussivu: 79
Lopetussivu: 85
Sivujen määrä: 7
ISSN: 0908-8857
DOI: https://doi.org/10.2307/3677344
Tiivistelmä
The abundances of potential avian prey species may be lower in the vicinity of the nests of predatory birds than farther away. We predicted that, if this density depression is due to predation, the observed density pattern should develop gradually during the breeding season as raptors deplete the prey populations. In contrast, if the low abundance is a result of predator avoidance during breeding habitat selection, the observed pattern should be evident from the beginning of the breeding season. We tested these predictions by counting breeding birds along transect lines (length 700 m, width 100 m) radiating away from Kestrel Falco tinnunculus nests, and along control transect lines situated >1000 m from Kestrel nests, five times in the course of the 1994 breeding season in western Finland. Breeding bird density was ca. 25% lower within 700 m of the Kestrel nests than on control sites. The positive relationship between bird densities and the distance from Kestrel nests was most evident in the early breeding season, which supports the predator avoidance hypothesis. The effect of predator presence on the distribution of breeding pairs seemed to be weak at species level but stronger at community level. At the beginning of the breeding season, distance from predator nests explained a larger proportion of the observed variation in the number of birds or species than any of the habitat variables used.
The abundances of potential avian prey species may be lower in the vicinity of the nests of predatory birds than farther away. We predicted that, if this density depression is due to predation, the observed density pattern should develop gradually during the breeding season as raptors deplete the prey populations. In contrast, if the low abundance is a result of predator avoidance during breeding habitat selection, the observed pattern should be evident from the beginning of the breeding season. We tested these predictions by counting breeding birds along transect lines (length 700 m, width 100 m) radiating away from Kestrel Falco tinnunculus nests, and along control transect lines situated >1000 m from Kestrel nests, five times in the course of the 1994 breeding season in western Finland. Breeding bird density was ca. 25% lower within 700 m of the Kestrel nests than on control sites. The positive relationship between bird densities and the distance from Kestrel nests was most evident in the early breeding season, which supports the predator avoidance hypothesis. The effect of predator presence on the distribution of breeding pairs seemed to be weak at species level but stronger at community level. At the beginning of the breeding season, distance from predator nests explained a larger proportion of the observed variation in the number of birds or species than any of the habitat variables used.
Turun yliopiston Tutkimustietojärjestelmän portaali