Recovery Plan for the Northern Spotted Owl - DRAFT

years. The strategy of managing for many local populations within themetapopulation should allow maintenance of a nondeclining trend in themetapopulation despite this variation.The management for local populations within the metapopulation also shouldbe designed to reduce the risk of local or widespread extirpation of owl populationsdue to catastrophic destruction of habitat. Such destruction could resultfrom natural causes including windthrow, fire, flooding, insects, diseases,volcanic action, or climatic change. The risk to the overall population fromlarge-scale disturbances is reduced by distributing local population centersacross the species' range, and by providing redundancy of habitats. Additionalsecurity from catastrophic loss can be provided by reducing the risk withinlocal population centers. The risk of catastrophic loss within a given populationcenter can be influenced by the size, configuration, and management ofthat center. Larger areas are less susceptible to complete elimination from fireand windthrow. The likelihood of fire, and the likely impacts of fire, can bereduced through management of fuels both within the population center and inthe surrounding forest matrix. In some ecological conditions, the risk ofserious insect and disease losses may be reduced through appropriate management.Habitat conditions and spacing between local populationsmust providefor survival and movement of northern spottedowls.Metapopulations are sets of local populations that are linked by dispersingindividuals. While each local population might be subject to extirpation overthe long term, individuals dispersing among the areas help to reestablish localpopulations after severe local declines or extirpations. The interbreedingprovided by dispersing individuals also provides insurance against deleteriouseffects of inbreeding. To allow for movement of northern spotted owls amongsource areas, those areas must be spaced appropriately; there must be redundantlinkages among areas; and the intervening habitat must provide thedispersal needs of adults and juveniles.Studies of dispersing juvenile owls (Miller 1989, Gutierrez et al. 1985) indicatethat their initial movements have a strong random component. The probabilityof a juvenile finding suitable habitat is related to the amount of suitablehabitat in the landscape around its natal area and the distance of that habitatfrom its starting point. Increasing the number of blocks of suitable habitatwithin the dispersal distance of any given local population center will increasethe chance for success of dispersing juveniles. Also, having each block withinthe dispersal distance of two or more other blocks allows the system of localpopulation centers to retain connectivity even if a given local population iseliminated. In this case, that population center can be reoccupied by owlscoming from two or more other centers.The connecting zones among local population centers must contain habitatthat will allow movement of juvenile and adult dispersers and provide for basiclife needs during the dispersal period. Key elements for survival includeroosting opportunities, protection from predators, and adequate foragingopportunities (Thomas et al. 1990).102