Habitat characteristics of Spotted Owl roosting sites (Strix occidentalis lucida) in the Sierra Madre Occidental, Mexico

Abstract

The Spotted Owl (Strix occidentalis lucida) is a threatened species and little has been studied in Mexico. In this study, we characterized its habitat at roosting sites (reproductive and non-reproductive) and at random sites (sites where the species is distributed randomly without a pattern) in Aguascalientes, Durango and Zacatecas and identified the physical and biological (habitat) variables they select. We used descriptive statistics and determined through a Poisson Regression (PRA) those variables that had an effect on the registered owls; we also grouped the variables identified by the pra with a Simple Correspondence (ACS) analysis and performed a Kruskal-Wallis test to detect possible significant differences between sites (rest and random). We located 29 owls (pairs, chicks and solitary individuals) in 11 roosting sites in oak-pine forests (63.6%) and in slopes with northern exposure and more inclined than those of random sites. The reproductive sites were located at a higher elevation, compared with non-reproductive and random sites; we also found at these sites, a greater tree density and with perching and dead trees of greater dimensions compared with trees found at non-reproductive and at random sites. However, only the tree density variable was statistically different (P < 0.05) between sites. The vegetation variables that were most associated with the roosting sites of the spotted owl were the tree height of the perch tree, the shrub cover and DBH of the perch tree. This information can be used in management and conservation plans of the subspecies in Mexico.

Keywords

• encinos
• sitios aleatorios
• sitios de descanso
• sitios reproductivos
• variables.