Design of a Monitoring Program for Northern Spotted Owls

Abstract

This paper discusses methods for estimating population trends of Northern Spotted Owls (Strix occidentalis caurina) based on point counts. Although the monitoring program will have five distinct components, attention here is restricted to one of these: roadside surveys of territorial birds. Analyses of Breeding Bird Survey data and computer simulations were used to develop recommendations for design of the roadside surveys. An approach known as "lattice sampling," in which some stations are visited annually and other stations are visited less often, may offer some advantages over the more common practice in wildlife surveys of visiting every station once per year. The analyses suggest that an adequate sample of the roadside surveys could be obtained with less than one person-year of effort per year per state, an expenditure well within current efforts for surveying Northern Spotted Owls, and that a minimum of 8 years, and probably at least 10 years of survey data will be required to obtain reliable estimates of long-term population trends.

Parent Publication

• Monitoring bird populations by point counts

Citation

Bart, Jonathan; Robson, Douglas S. 1995. Design of a Monitoring Program for Northern Spotted Owls. In: Ralph, C. John; Sauer, John R.; Droege, Sam, technical editors. 1995. Monitoring bird populations by point counts. Gen. Tech. Rep. PSW-GTR-149. Albany, CA: U.S. Department of Agriculture, Forest Service, Pacific Southwest Research Station: p. 75-82