Nest-Site Preferences of Flammulated Owls in Western New Mexico

Abstract

We studied nest-site preferences of Flammulated Owls (Otus flammeolus) in the Zuni Mountains of western New Mexico and used multivariate analyses of the nest cavity, nest tree, and surrounding woody vegetation to ask if and then how the birds select nest sites. Significantly reduced variance in used compared to unused sites for both cavity/nest-tree and vegetation data indicates that the used sites are a nonrandom subset of the source pool (i.e., the birds are selective). Preferred cavities are modal in the source pool, but preferred vegetation is characterized by low shrub density, high canopy height, and high importance of mature Pinus edulis. Preferred vegetation characteristics appear more limited than preferred cavity/nest-tree characteristics. Nest sites have fewer shrubs in front of than behind the cavity entrance. This is consistent with the species' habit of flying at shrub level upon approaching and leaving the nest. The suggestion that Flammulated Owls have increased in abundance with increasing vegetative density is not supported.