Territory size and overlap in male Ovenbirds: contrasting a fragmented and contiguous boreal forest

Abstract

We evaluated if male age and body size, density of conspecifics, and arthropod biomass contributed to variation in territory size and overlap of Ovenbirds, Seiurus aurocapillus (L., 1766), in a fragmented and contiguous boreal forest. Territory size and overlap were determined by radio-tracking territorial male Ovenbirds in fragmented (n = 22) and contiguous forest (n = 13) from late May to the end of June 1999 and 2000. Variation in male territory size was most strongly associated with individual characteristics, specifically body size and age. Furthermore, we found strong support for an effect of density of conspecifics on territory overlap, suggesting that the exclusivity of territories and perhaps levels of territoriality were greater for males in contiguous forest than for those in fragments. Our findings (i.e., mean territory size was similar between landscapes and territory overlap was greater in fragments than in contiguous forest) suggest that fragments either have larger areas of unsuitable habitat or are less saturated with Ovenbirds. Furthermore, because resources were not distributed equally among individuals, our results were consistent with the ideal dominance model of habitat selection. Finally, previous studies based on acoustical surveys have likely underestimated space-use requirements in forest passerines.