title: Habitat selection rules in breeding mallards (Anas platyrhynchos): a test of two competing hypotheses.
abstract: Ideal preemption and conspecific attraction are alternative hypotheses of the habitat selection rules used by individuals. According to the former an occupied site is assumed to be preempted and therefore not available for later arriving individuals, whereas according to the latter individuals are assumed to be attracted by conspecifics to occupied sites, rather than avoiding them. We studied these competing hypotheses in breeding mallards (Anas platyrhynchos) by a cross-over experiment in 2 years, introducing birds onto lakes before migratory wild mallards arrived. If mallards use the ideal preemptive rule, breeding density of wild mallards in experimental lakes should be lower and they should be occupied less frequently than control lakes, but if mallards use the conspecific attraction rule the reverse should be true. Our results allowed us to reject the ideal preemptive rule whereas the conspecific attraction rule was to some extent supported. We discuss these findings in relation to population limitation. The results suggest that the local breeding population studied is not limited by spacing behaviour related to habitat selection.
authors.affiliation: Finnish Game and Fisheries Research Institute, Evo Game Research Station, Kaitalammintie 75, FIN-16970 Evo, Finland Fax: +358 205 751 459; e-mail: hannu.poysa@rktl.fi, , , , , , FI.
authors.forename: Hannu
authors.initials: H
authors.lastname: Pöysä
authors.affiliation: Department of Animal Ecology, Swedish University of Agricultural Sciences, S-901 83 Umeå, Sweden, , , , , , SE.
authors.forename: Johan
authors.initials: J
authors.lastname: Elmberg
authors.affiliation: Department of Animal Ecology, Swedish University of Agricultural Sciences, S-901 83 Umeå, Sweden, , , , , , SE.
authors.forename: Kjell
authors.initials: K
authors.lastname: Sjöberg
authors.affiliation: Department of Applied Zoology, University of Helsinki, P.O. Box 27 (Viikki, C), FIN-00014 University of Helsinki, Finland, , , , , , FI.
authors.forename: Petri
authors.initials: P
authors.lastname: Nummi
keywords: Conspecific attraction; Habitat selection; Ideal preemptive distribution; Key wordsAnas platyrhynchos; Population limitation