Recovery Plan for the Northern Spotted Owl - DRAFT

Each program is discussed briefly here. We review what information is needed,how much has been learned already, and what work should receive highestpriority in the next few years. Much of this work is already in progress (thoughin most cases for purposes other than the development of a comprehensivemonitoring program). As noted earlier, these suggestions are preliminary andwill need considerable discussion and refinement.Estimating or predicting population trends is the main objective of thesemonitoring programs, but the information they provide also could be useful inother aspects of the recovery program. For example, the roadside surveyscould provide indications of relative abundance in young landscapes with andwithout remnant old-growth stands or individual trees. This information couldbe useful to silviculturalists studying ways to accelerate development of suitablehabitat. In the following discussion, we attempt to identify some of theseobjectives and suggest how the monitoring program can be designed to helpachieve them as well as achieve the primary goal of estimating or predictingpopulation trends.Roadside surveysA great deal of effort already has been expended in developing techniques forcalling owls, and these studies provided an excellent basis for designing theroadside survey. Little if any additional field work may be needed, but severalanalyses, discussed here, are needed.1. Estimate variance components from samples of survey data.The computer program described earlier would provide more reliable predictionsof power if estimates were available of the average number of birdsrecorded per station, and if the covariance structure in the data set wasbetter defined, in different environments and portions of the range. Thedata needed for such analyses already have been collected, for example bythe Forest Service monitoring programs and within the density study areas.2. Estimate "road bias" and ways that it can be reduced.As noted in the description of roadside surveys, the savings in labor realizedfrom restricting the surveys to roads (except in roadless areas such aswilderness areas) are so great that this approach probably should be followedin most areas. Numerous possibilities exist, however, for such arestriction to cause bias in trend estimates. For example, habitat is probablymore fragmented near roads, may be more fragmented than far fromroads, and population trends might therefore be different along roads and inthe entire region. These possibilities can be assessed best by using thegeographic information system (GIS) developed by the Recovery Team. Itmay be possible to stratify the range (e.g., into categories based on fragmentation)and to consider that within strata the roadside stations constitute arandom sample.3. Development of the double-sampling approach.Completion of the two tasks just discussed will provide the basis for finaldevelopment of the double-sampling approach suggested for the roadsidesurveys. Estimates will be available of numbers of birds likely to be recordedper station in different strata and how these numbers will varythrough space and time. This information can be used to develop morerealistic formulas and simulations for estimating power and sample sizerequirements, and for suggesting allocation of effort among different strata.The result probably will be a program somewhat like the one used earlier to271