Spatial patterns of burrowing owl (Speotyto cunicularia) nests within black-tailed prairie dog (Cynomys ludovicianus) towns

Abstract

The spatial patterns of burrowing owl (Speotyto cunicularia) nests in black-tailed prairie dog (Cynomys ludovicianus) towns were examined in the Nebraska panhandle during the spring and summer of 1989–1991. Because of higher nest densities (≥ 0.20 nests/ha) and internest distance requirements, it was not possible for owls to demonstrate patterns other than random in the smaller (< 35 ha) prairie dog towns. In large prairie dog towns (> 35 ha), burrowing owls were less dense (≤ 0.20 nests/ha), and choice of nest sites by pairs resulted in a clumped nest distribution. In prairie dog towns < 35 ha, nearest neighbor distance was positively related to prairie dog town size, whereas no relationship was found between prairie dog town size and nearest neighbor distance for towns ≥ 35 ha. Burrow availability was not responsible for clumping. Ample burrows were available throughout the towns in 1990 and 1991. In 1991, two towns with clumped distributions of owls showed no differences in numbers of burrows around active owl nests and random burrows throughout the towns. Other possible explanations for clumping, including food availability and reduced predation risk, are discussed.