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1 September 2014 Breeding dispersal of Mexican Spotted Owls in the Sacramento Mountains, New Mexico
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Dispersal is a key process influencing population dynamics and gene flow in species. Despite this, little is known about breeding dispersal in threatened Mexican Spotted Owls (Strix occidentalis lucida), here defined as movement of a non-juvenile owl between territories where it had the opportunity to breed. We observed 28 cases of breeding dispersal during a study of color-banded Mexican Spotted Owls in the Sacramento Mountains, New Mexico, 2003–2011. This represented 4.9% of total opportunities to disperse (n  =  575 observed occasions, range  =  0–9.0% of owls dispersing per yr). Breeding dispersal probability was greater for single owls and paired owls whose mate disappeared or moved than for paired owls whose mate remained in the original territory, greater for subadult than for adult owls, and greater for owls that failed to reproduce the year prior to dispersing than for owls that reproduced successfully. There was some evidence that dispersal probability was greater for female owls and that females dispersed greater distances than males, but dispersal distances generally were small for both sexes of owls (mean distance  =  5.1 and 3.6 km for females and males, respectively). All dispersing owls were paired the first year they were observed in their new territory. Breeding dispersal appeared to occur regularly but at relatively low levels in this population, and dispersal probability appeared to be associated with owl social status, reproductive status, and age prior to dispersal. Because most dispersing owls either were unpaired or lost their mate, and because most failed to reproduce the year prior to dispersal, these owls generally were able to improve their social status and reproductive success by dispersing.

2014 by the Wilson Ornithological Society
Joseph L. Ganey, Darrell L. Apprill, Todd A. Rawlinson, Sean C. Kyle, Ryan S. Jonnes, and James P. Ward "Breeding dispersal of Mexican Spotted Owls in the Sacramento Mountains, New Mexico," The Wilson Journal of Ornithology 126(3), 516-524, (1 September 2014).
Received: 9 January 2014; Accepted: 1 April 2014; Published: 1 September 2014

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