Heterospecific attraction and food resources in migrants' breeding patch selection in northern boreal forest |
| |
Authors: | Jukka T Forsman Mikko Mönkkönen Pekka Helle Jouko Inkeröinen |
| |
Institution: | (1) Department of Biology, University of Oulu, POB 333, FIN-90571 Oulu, Finland Fax +358-8-5531227; e-mail: jforsman@paju.oulu.fi, FI;(2) Finnish Game and Research Institute, Meltaus Game Research Station, FIN-97340 Meltaus, Finland, FI |
| |
Abstract: | We studied experimentally how heterospecific attraction may affect habitat selection of migrant passerine birds in Finnish
Lapland. We manipulated the densities of resident tit species (Parus spp.). In four study plots residents were removed before the arrival of the migrants in the first study year, and in four
other plots their densities were increased by releasing caught individuals. In the second year the treatments of the areas
were reversed, allowing paired comparisons within each plot. We also investigated the relative abundance of arthropods in
the study plots by the sweep-net method. This allowed us to estimate the effect of food resources on the abundance of birds.
The heterospecific attraction hypothesis predicts that densities of migrant species (especially habitat generalists) would
be higher during increased resident density. Results supported this prediction. Densities and number of the most abundant
migrant species were significantly higher when resident density was increased than when they were removed. On the species
level the redwing (Turdus iliacus) showed the strongest positive response to the increased abundance of tits. Migrant bird abundances seemed not to vary in
parallel with relative arthropod abundance, with the exception of the pied flycatcher (Ficedula hypoleuca) which showed a strongly positive correlation with many arthropod groups. The results of the experiment indicate that migrants
can use resident tit species as a cue to a profitable breeding patch. The relationship between the abundance of the birds
and arthropods suggests that annual changes in food resources during the breeding season probably do not have a very important
effect on bird populations in these areas. The results stress the importance of positive interspecific interactions in structuring
northern breeding bird communities.
Received: 1 September 1997 / Accepted: 22 January 1998 |
| |
Keywords: | Heterospecific attraction Positive interactions Competition Habitat selection Food resources |
本文献已被 SpringerLink 等数据库收录! |
|