Spotted owl demography in the central Sierra Nevada

There has been a great deal of controversy over the status of spotted owl (Strix occidentalis) populations in western North America. Therefore, we estimated the population dynamics of a population of California spotted owls (S. o. occidentalis) in the central Sierra Nevada. We assessed reproductive status at 62 territories on 253 occasions over a 10-year period and recorded 714 captures of 210 individuals over a 14-year period. Reproduction varied temporally but did not exhibit any noticeable trends, whereas survival followed a quadratic pattern: owls experienced higher survival during the middle years of the study. Demographic parameter estimates indicate that the population declined 5.2% (SE = 2.6) per year from 1990-1999. Although conditions behind this decline may change in the future, these results suggest that management of spotted owl populations and maintaining their habitat are high conservation priorities in the central Sierra Nevada.