Abstract

Differential migration timing between sex or age classes is an example of how migratory movement strategies can differ among subgroups within a population. However, in songbirds, evidence for intrinsic differences in en route migratory behaviour is often mixed, suggesting that the local environmental context may play a role in accentuating or diminishing patterns. We evaluated how multiple intrinsic and extrinsic variables influenced refuelling rates, local movement behaviour and departure decisions in the white-throated sparrow Zonotrichia albicollis during spring migration. This species exhibits a unique genetically based plumage dimorphism, providing a unique class of individual in which to evaluate patterns and processes of differential migration, in addition to sex, age and migration distance. At a migratory stopover site, plasma metabolite analysis was used to quantify individual variation in stopover refuelling rate. In after second year adults, automated and manual radio telemetry was used to quantify daily activity timing, daily movement distances, stopover duration and departure time. Arrival timing to the stopover site was determined using capture data. Non-breeding and previous breeding/natal latitude were determined using analysis of hydrogen isotopes in claws and feathers. Males arrived at the stopover site 11days on average before females, but no difference in migration timing was observed between plumage morph or age classes. After second year, adults with more southern previous breeding latitudes arrived at stopover earlier, whereas second year birds making their first return migration arrived at stopover in an inverse relationship to non-breeding latitude. Stopover refuelling rate did not differ between ages, sexes or plumage morphs, and daily departure probability of adults was higher under warmer temperatures and favourable tailwinds. White-striped morphs moved greater distances during stopover, initiated daily activity earlier in the morning and departed for migration earlier in the evening than tan-striped morphs. Our results show that while individual phenotype can influence some aspects of local stopover-scale movement behaviour, evidence for differential stopover behaviour was weak. Differential migration timing is unlikely to result from intrinsic differences in en route refuelling rate and departure decisions, especially because the latter is strongly influenced by meteorological conditions.

Full Text
Paper version not known

Talk to us

Join us for a 30 min session where you can share your feedback and ask us any queries you have

Schedule a call

Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.