Breeding dispersal of Mexican Spotted Owls in the Sacramento Mountains, New Mexico

Abstract

ABSTRACT 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 th...