Recovery Plan for the Northern Spotted Owl - DRAFT

IntroductionMore than 450 species of birds, mammals, and amphibians occur in forestswest of the crest of the Cascade Mountains in Oregon and Washington (Brown1985:37), as well as 178 species of freshwater and anadromous fishes. Thenumber of plant species in this area is also large and the number of invertebratespecies is large, but cannot be determined accurately because manyarthropods and molluscs have not been described and named (J. Lattin,Oregon State University; T. Frest, Deixis Consultants, pers. comm.). However,more than 3,400 species of arthropods have been reported from the H.J.Andrews Experimental Forest in the Oregon Cascade Mountains (Parsons et al.1991). The Cascades region is about three times richer in mammalian speciesand about twice as rich in species of breeding birds as the coniferous forests ofthe coastal plains of the southeastern United States (Harris 1984:45). Thishigh species richness reflects a great diversity of communities, ranging fromestuarine to freshwater, from coastal to montane, and from prairie to temperaterain forest. Of the higher vertebrates (those other than fishes), about 58percent are birds, 30 percent are mammals, 7 percent are amphibians, and 5percent are reptiles (Harris 1984:47). In addition to the high species richnessof mammals and birds, many unique faunal types are endemic to the PacificNorthwest. For example, the genus Phenacomys (Arborimus: tree voles) occursonly in western Oregon and northwestern California, and the region has morespecies of mammalian insectivores than any other part of temperate NorthAmerica. Numerous species are narrowly or broadly endemic to westernOregon and Washington and northwestern California. The region also containsseveral unique species, such as the tailed frog, one of the most primitive extantamphibians, which has been essentially unchanged in the fossil record formillions of years. Although the amphibians are not as rich in species as thebirds and mammals, most of the species are narrowly or broadly endemic tothe Pacific Northwest (e.g., Oregon slender salamander, Siskiyou Mountainsalamander) (Bury et al. 1991). In addition, there is evidence of a decline ofamphibian populations in many parts of the world (Blaustein and Wake 1990).The number of amphibians that are associated closely with streams (Bury1988) and the many dwindling fish stocks (Nehlsen et al. 1991) exemplify theimportance of riparian ecosystems in coniferous forests.The northern spotted owl is associated with older forest ecosystems in thePacific Northwest (Forsman et al. 1984, Thomas et al. 1990), and optimalhabitat for the species usually is found in old-growth forests that are morethan 200 years old. Because of its association with older coniferous forests,the spotted owl has been used as an indicator species for older forest ecosystems.The owl is well-suited for this role in many respects because of itspreference for mature or old-growth forests and its large home range size thatvaries from 1,000 to 10,000 acres from California to northern Washington(Thomas et al. 1990:194). The amount of mature and old-growth forest withina pair's home range also varies considerably from north to south (Thomas et al.1990:195). The species' preferred habitat for nesting, roosting, and foragingthroughout most of its range is old-growth coniferous forests. However, olderforests are extremely diverse in structure and function, and it is clear that theowl can not represent all the key components of these forests.Secretary of the Interior Lujan's charge to the Recovery Team included thefollowing statement: 'There are other forest ecosystem species that may becandidates for listing under the Endangered Species Act which may benefitfrom any recovery plan for the northern spotted owl. To the extent possible,the team should assess the relative benefits to these species from the implementationof various recovery options" (memo to the Recovery Team: February5, 1991). As a result of this directive, a committee of the Recovery Team was333