Estimating natal origins and migratory patterns of juvenile raptors banded during fall migration at Hawk Ridge Duluth, MN

Abstract

Effective conservation of migratory species requires knowledge of the many geographic locations utilized during their full annual cycle. Determining breeding location can be challenging due to the secretive nature of many raptors on their breeding grounds; however, during migration, these species are relatively easy to study since large numbers of individuals fly through migration corridors. The objective of this research was to improve our understanding of full annual cycle landscape use by identifying the breeding origin and migratory patterns of juvenile raptors utilizing hydrogen stable isotope analysis of feathers (ẟ2Hf) collected during fall migration at Hawk Ridge in Duluth, Minnesota. We found that ẟ2Hf was able to elucidate temporal migration patterns and broadly assign natal origins. However, assignments remain broad and could be improved by the addition of other techniques. Knowledge of breeding locations and migratory patterns is important for connecting ecological variables on breeding grounds to observed population changes during migration and placing Hawk Ridge’s long-term monitoring data within a geographical framework.