Fidelity to territory and mate and the causes and consequences of breeding dispersal in American goshawk (Astur atricapillus).

Using mark-resight data, we investigated fidelity to territory and mate as well as breeding dispersal rates and the causes and consequences of breeding dispersal in a 20-year study of American goshawks (Astur atricapillus) in Arizona, USA. Generalized Additive Mixed Models were used to identify the...

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Main Authors: Richard T Reynolds, Shannon L Kay, Jeffrey S Lambert, Martha Ellis
Format: Article
Language:English
Published: Public Library of Science (PLoS) 2025-01-01
Series:PLoS ONE
Online Access:https://doi.org/10.1371/journal.pone.0323805
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author Richard T Reynolds
Shannon L Kay
Jeffrey S Lambert
Martha Ellis
author_facet Richard T Reynolds
Shannon L Kay
Jeffrey S Lambert
Martha Ellis
author_sort Richard T Reynolds
collection DOAJ
description Using mark-resight data, we investigated fidelity to territory and mate as well as breeding dispersal rates and the causes and consequences of breeding dispersal in a 20-year study of American goshawks (Astur atricapillus) in Arizona, USA. Generalized Additive Mixed Models were used to identify the relative contributions of four prominent explanatory variables (eggs laid, nest failed, nest successful, mate loss) and 21 individual and environmental variables in a machine learning Conditional Inference Forest to predict breeding dispersal. Ninety-five percent of males and 92% of females exhibited lifetime territory fidelity and 97% exhibited lifetime mate fidelity. Mate loss alone (to divorce, possible emigration or death) made the biggest difference in the predicted probability of dispersal (0.11 with mate loss, 0.005 with mate retention). Yet, in 80% of mate losses a hawk stayed on its territory to eventually nest with a new mate. Territory fidelity was highest when the mate was retained in the next breeding and the pair's previous attempt produced fledglings. All males and 86% of females that dispersed to a territory in our study area moved no farther than to a 3rd-order neighboring territory (crossed 2 territories). Despite equivocal evidence of dispersal to territories more frequently occupied by egg-layers, there was otherwise little evidence that hawks on average dispersed to better territories. On average reproduction did not improve post-dispersal and dispersers did not move to territories with greater total (all monitored yrs) reproduction. Goshawks losing their mates appeared to use a home-based mate searching that minimized loss of a familiar territory by waiting on their territory for a new mate and prospecting nearby territories for unpaired mates. The small sample of nearby prospected territories, combined with fortuitous occurrences of unpaired mates, resulted in random (with respect to quality) selections of territories by dispersers.
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spelling doaj-art-7d6a1ad7be3d4700b291289ecb26f8ef2025-08-20T03:08:27ZengPublic Library of Science (PLoS)PLoS ONE1932-62032025-01-01205e032380510.1371/journal.pone.0323805Fidelity to territory and mate and the causes and consequences of breeding dispersal in American goshawk (Astur atricapillus).Richard T ReynoldsShannon L KayJeffrey S LambertMartha EllisUsing mark-resight data, we investigated fidelity to territory and mate as well as breeding dispersal rates and the causes and consequences of breeding dispersal in a 20-year study of American goshawks (Astur atricapillus) in Arizona, USA. Generalized Additive Mixed Models were used to identify the relative contributions of four prominent explanatory variables (eggs laid, nest failed, nest successful, mate loss) and 21 individual and environmental variables in a machine learning Conditional Inference Forest to predict breeding dispersal. Ninety-five percent of males and 92% of females exhibited lifetime territory fidelity and 97% exhibited lifetime mate fidelity. Mate loss alone (to divorce, possible emigration or death) made the biggest difference in the predicted probability of dispersal (0.11 with mate loss, 0.005 with mate retention). Yet, in 80% of mate losses a hawk stayed on its territory to eventually nest with a new mate. Territory fidelity was highest when the mate was retained in the next breeding and the pair's previous attempt produced fledglings. All males and 86% of females that dispersed to a territory in our study area moved no farther than to a 3rd-order neighboring territory (crossed 2 territories). Despite equivocal evidence of dispersal to territories more frequently occupied by egg-layers, there was otherwise little evidence that hawks on average dispersed to better territories. On average reproduction did not improve post-dispersal and dispersers did not move to territories with greater total (all monitored yrs) reproduction. Goshawks losing their mates appeared to use a home-based mate searching that minimized loss of a familiar territory by waiting on their territory for a new mate and prospecting nearby territories for unpaired mates. The small sample of nearby prospected territories, combined with fortuitous occurrences of unpaired mates, resulted in random (with respect to quality) selections of territories by dispersers.https://doi.org/10.1371/journal.pone.0323805
spellingShingle Richard T Reynolds
Shannon L Kay
Jeffrey S Lambert
Martha Ellis
Fidelity to territory and mate and the causes and consequences of breeding dispersal in American goshawk (Astur atricapillus).
PLoS ONE
title Fidelity to territory and mate and the causes and consequences of breeding dispersal in American goshawk (Astur atricapillus).
title_full Fidelity to territory and mate and the causes and consequences of breeding dispersal in American goshawk (Astur atricapillus).
title_fullStr Fidelity to territory and mate and the causes and consequences of breeding dispersal in American goshawk (Astur atricapillus).
title_full_unstemmed Fidelity to territory and mate and the causes and consequences of breeding dispersal in American goshawk (Astur atricapillus).
title_short Fidelity to territory and mate and the causes and consequences of breeding dispersal in American goshawk (Astur atricapillus).
title_sort fidelity to territory and mate and the causes and consequences of breeding dispersal in american goshawk astur atricapillus
url https://doi.org/10.1371/journal.pone.0323805
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