FACTORS INFLUENCING BURROWING OWL (SPEOTYTO-CUNICULARIA) NEST DENSITIES AND NUMBERS IN WESTERN NEBRASKA

Burrowing owls (Speotyto cunicularia) were studied at 21 prairie dog t owns in native prairie and 17 native prairie pastures with badger (Tax idea taxus) burrows in the Nebraska panhandle in the spring and summer from 1989-1991. The number of nesting burrowing owl pairs ranged from 1-20 in prairie dog (Cynomys ludovicianus) towns and from 1-4 in past ures with badger burrows. Burrowing owl densities in small prairie dog towns (<35 ha) varied between 0.1-30.0 owls/ha; densities in large pr airie dog towns (greater than or equal to 35 ha) ranged from 0.03-0.4 owls/ha, and densities in burrowing owl clusters within large (greater than or equal to 35 ha) prairie dog towns ranged from 0.9-2.5 owls/ha . Mean nearest-neighbor distance (+/-SE) in clusters within large (gre ater than or equal to 35 ha) prairie dog towns was 125.0 m +/- 4.6, wh ereas the mean distance between owl nests in small towns (<35 ha), whe re owls did not have the space to cluster, was 105.1 m +/- 7.4. Mean n earest-neighbor distance for owls nesting in pastures with badger burr ows was 240.2 m +/- 39.2. No relationship was found between owl number s and number of active or inactive prairie dog burrows. In 1990 burrow ing owl density was inversely related to active burrow density, but no relationship was found in 1991. Burrow availability may be a limiting factor for owls nesting in pastures with badger burrows. As the size (ha) of prairie dog towns increased, burrowing owls occurred in higher numbers but lower densities.