Space-use strategies of wintering Ovenbirds in Belize: causes and consequences

作者：Kresnik Ross J; Stutchbury Bridget J M^*

来源：Journal of Field Ornithology, 2014, 85(3): 274-288.

DOI：10.1111/jofo.12067

• body condition
• Neotropical migrant
• Seiurus aurocapilla
• space use
• wanderer
• winter territoriality

For long-distance migrants, territoriality and prey biomass during the non-breeding season have been linked to body condition that can carry over to affect spring migration and breeding events. For Ovenbirds (Seiurus aurocapilla), studies in Jamaica showed that body condition in mid-season depended on leaf litter prey biomass and declined seasonally as conditions became drier, and that individuals with sedentary (territorial) and wandering space-use strategies did not differ in age or body condition. During October and November 2010-2011, we radio-trackedOvenbirds in Belize to determine if space-use patterns differed with age and sex, if space-use strategy influenced foraging behavior or body condition, and if areas used by wanderers and territory owners differed in food abundance or habitat characteristics. Most Ovenbirds (41 of 51, 80.4%) possessed small (1-ha) territories with largely non-overlapping cores, but 22.5% (10 of 51) of birds were wanderers (similar to 7-ha home range). Early season space use was predicted by age class, with most wanderers (90%, 9 of 10) being first-year birds and most territory owners (63%) being older birds. Sex ratios of wanderers and territory owners did not differ. We found that wanderers may have been at a disadvantage because they had significantly lower foraging rates and lower relative body masses than territorial birds, although baseline corticosterone levels did not differ. Habitat characteristics of areas used by wanderers and territory owners did not differ nor did biomass of ground-surface arthropods, likely because ranges of most wanderers overlapped those of territory owners. Using stable hydrogen isotopes in feathers, we found that first-year Ovenbirds that were wanderers tended to have a more northern natal origins than sedentary birds, though the difference was not significant. Longer migration distances could delay arrival and reduce competitive ability. Our results suggest that wandering may not be an alternative and equally successful strategy, at least early in the season, and instead young birds may be competitively excluded from territory ownership.

• 出版日期2014-9