Title

Dispersal and Survival of Red-Shouldered Hawks Banded in Suburban Southern Ohio, 1996-2018

Document Type

Article

Publication Date

9-1-2019

Abstract

© 2019 The Raptor Research Foundation, Inc. We used banding data to investigate dispersal and survival of Red-shouldered Hawks (Buteo lineatus) in two study areas in southern Ohio from 1996 to 2018. Of the 2448 nestlings we banded, 167 (6.8%) were encountered (dead or alive) some time after banding. Mean distance from the natal nest at the time of encounter was 31.6 ± 6.2 km (median = 10.0, range = 0.1-568.6 km, n = 163); natal dispersal distance averaged 16.0 ± 1.9 km (median = 9.0, range = 1.4-117.1 km, n = 110), and was significantly greater for females than for males. Most hawks dispersed <30 >km, but 11 hawks (6.7%) dispersed >100 km from their natal nest. Of these long-distance dispersers, nine (82%) were old, suggesting that some young birds wander widely prior to breeding. Dispersal distance differed by sex and age at encounter, with dispersal distance negatively correlated with age at encounter, and females dispersing farther (39.8 ± 12.3 km) than males (22.8 ± 9.86 km) and unknown-sex birds (33.9 ± 10.6 km; all P < 0.05; means estimated from the logistical regression model). Dispersal direction for all birds followed a uniform distribution (P > 0.05); however, dispersal direction of long-distance dispersers was not uniform (P < 0.05) but bimodal, with hawks encountered either to the south or to the northeast of the study area. Mean age at recovery was 2.6 ± 0.3 yr (median = 1.5 yr, range = 0.2-10.3 yr). As in other raptor species, apparent annual survival varied between age classes, with young birds (hatch-year and second-year) having lower apparent annual survival (0.49 ± 0.03) than adult birds (0.76 ± 0.03). Our study provides information on dispersal, survival, and causes of mortality of Red-shouldered Hawks, demographic data that are important for evaluating population trends and the sustainability of urban/suburban populations.

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