Recovery Plan for the Northern Spotted Owl - DRAFT

Table B.1. Roles and relative importance of different kinds of information abouthabitat suitability in making assessments and predictions about owl viabilitya.Step In Making Assessments or PredictionsMeasure of Define Measure Evaluate BasisHabitat Habitat Habitat forSuitability Categories Suitability ExtrapolationStructuralFeatures ofUtilizedHabitats XXX XAmounts ofHabitat inHome Ranges X XXPreference forRoosting andForaging XX XAbundance ofOwls inDifferentHabitats XX XDemographicRates inDifferentHabitats XXX XXStudies ofSpecificResources XXX XX XXXa XXX = most important; e= east important................... - - I I ....... - 1.11- 1- 1- 1.11 ..... 11 I .......... I -............." I'll - - ....... S~~~~~~~~~~~~~~~the hypothesis that retaining large trees creates suitable habitats. Functionalstudies are needed, however, to reveal whether large trees cause the highdensity of owls (compared to existing stands without large trees) or whether thelarge trees are simply correlates of some other feature that occurs in theexisting habitats but might not occur as a result of the silvicultural manipulation.Much of the effort in the recovery program will be devoted to identifying habitatsthat are "suitable" for owls at the stand, territory, and landscape level. Alltypes of habitat study have contributions to make in this effort. Suppose, forexample, that we have defined a habitat, call it Type A, that we believe mightprovide all of the resources needed by owls to maintain viable populations.We would first define the habitat using structural measures such as averagedbh, canopy cover, and presence of a hardwood understory. We would thenuse several types of information to evaluate the hypothesis that Type A habitatwas suitable for owls.289