A Revision to the Distribution of Plumage Polymorphism in the Red-Tailed Hawk (Buteo jamaicensis)

Abstract

Aim

The high proportion of plumage polymorphism in raptor species presents exciting research potential. Unfortunately, fundamental knowledge gaps remain that limit our ability to fully understand the development and role of plumage polymorphism in this group and extend those insights to vertebrates as a whole. We report data that fills one such knowledge gap in the red-tailed hawk (Buteo jamaicensis) that will enable investigations to uncover factors that influence the biogeography of plumage polymorphism in the species and raptors more generally.

Location

North America.

Taxon

Buteo jamaicensis (red-tailed hawk).

Methods

We captured and outfitted four dark and 22 light morphs with GPS/GSM satellite transmitters during the non-breeding season in the Great Lakes region of North America to assess their breeding provenance and behaviours. We calculated 95% AKDE nesting home ranges during an 80-day period meant to capture the incubation and brood-rearing periods and compared home ranges by age and sex to contextualise movements.

Results

Our results indicate that dark types nest in eastern Canada and belong to the same breeding population as the light individuals tagged in our study, extending the known distribution of plumage polymorphism in the species approximately 1500 km eastward into eastern Canada.

Main Conclusions

This revised distribution of plumage polymorphism is a critical first step for understanding the biogeography of plumage polymorphism and assessing drivers of within-population trait diversity in this species, and predatory vertebrates more generally.