Recovery Plan for the Northern Spotted Owl - DRAFT

predict the power achieved by different designs given numbers recorded perstation, number of stations per year, and so on. The new programs wouldbe similar, but would include the benefits gained from stratification anddouble-sampling.4. What "domains" to obtain estimates for?The term domain refers to a portion of a sampled population about whichinferences are desired. A domain might consist of a certain province, DCAsof a certain type, or a certain environment. Domains may be redefined indifferent analyses; they do not all have to be identified before the analysesare conducted, and in reality, new domains are nearly always defined as theanalysis proceeds. Much of the "art" in sampling involves trying to maximizethe number of new domains of interest that can be constructed andstudied after the data have been collected. The process, however, obviouslyis easier if the domains are specified during design of the sampling program.For spotted owls, domains of interest include provinces, states, DCAs,federal land outside of DCAs, and several different environments. Thetentative list of domains to be studied in the monitoring program should bedeveloped and used in making final sample size decisions.Activity site monitoringFor this sampling program, the owl's range (including the demographic areas)would be subdivided into strata as in the roadside survey program. The stratacould be different but there might be considerable advantage to having thesame strata in the two programs. The sample size within each stratum wouldbe determined, and areas would be chosen randomly (except for "censused"strata). The selected areas would be surveyed to identify all activity sites, andone or more sites would be selected randomly. These sites would be surveyedfor some minimum number of years. Surveys would be conducted according toan approved protocol and the birds present at each site in each year would bebanded so that turnovers could be identified. Productivity (number of fledglingsproduced) would be recorded, as would age of first-time territory holdersand replacement times. Habitat information also should be collected about theactivity site and surrounding area.The major tasks needed for initiation and refinement of this program includethe following:1. Decide on stratification procedure and sample size requirements.Most of the comments made earlier about designing the roadside surveysapply to this program as well. Existing data on productivity, turnover rate,age ratios, and replacement times should be studied to obtain advanceestimates of the parameter values and the covariance structure of the data.The possibility of roadside bias should be investigated. Domains of interestshould be identified in advance, as much as possible, and the design shouldstrive to accommodate the new domains that undoubtedly will be identifiedafter analysis begins. Domains for the activity site monitoring may bedefined using either landscape features or features of the habitat in theimmediate vicinity of the activity site.2. Develop a program for recording habitat information about the activity site.Standardized methods should be developed for collecting data on the habitatat the nest site and in the nearby areas. This work will involve decidingwhat areas around each site should be characterized, and what informationshould be collected. The information should serve the purposes of biologists272