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Federal Register / Vol. 69, No. 168/Tuesday, August 31,,2004/Rules and Regulations 53183 Recovery Plan for the Mexican Spotted Owl (Recovery Plan) (Service 1995). However, some of this information is discussed in our analyses below, such as the description of the primary constituent elements. Two primary reasons were cited for listing the owl as threatened in 1993: (1) Historical alteration of its habitat as the result of timber management practices, specifically the use of even -aged silviculture, and the threat of these practices continuing; and (2) the danger of catastrophic wildfire. The Recovery Plan for the owl outlines management actions that guide land management agencies in efforts to remove recognized threats and recover the owl. This critical habitat designation is based on recovery needs and guidelines identified in the Recovery Plan. The Recovery Plan provides for three levels of habitat management: protected areas, restricted areas, and other forest and woodland types. We define protected areas to include all known owl sites (Protected Activity Centers [PACs% and all areas in mixed - conifer or pine -oak types with slopes greater than 40 percent where timber harvest has not occurred in 20 years, and all legally and administratively reserved lands, such as Wilderness Areas or Research Natural Areas. Protected areas can also include steep - walled canyon habitat. Owl PACs are delineated around known owl sites. PACs include a minimum of 600 acres (ac) (243 hectares [ha)) that includes the best nesting and roosting (i.e., resting) habitat in the area. A PAC contains the nest site, a roost grove commonly used during the breeding season in the absence of a verified nest site, or the best nesting /roosting habitat if both nesting and roosting information are lacking and the most proximal and highly used foraging areas (Service 1995). Areas outside of PACs, including restricted areas, provide additional habitat appropriate for foraging. Restricted areas include mixed - conifer forest, pine -oak forest, and riparian areas where potential nesting and roosting habitat exist. Canyons may also contain restricted areas. The Recovery Plan provides less specific management guidelines for these areas. The Recovery Plan does not provide owl- specific guidelines for "other forest and woodland habitat." The owl occupies a broad geographical area, but does not occur uniformly throughout its range (Service 1995). Instead, the owl occurs in disjunct localities that correspond to isolated mountain systems and canyons. The owl is frequently associated with mature mixed - conifer, pine -oak, and riparian forests (Ganey et al. 1988, Skaggs and Raitt 1988, Ganey and Balda 1989, Gutierrez and Rinkevich 1991, Willey 1993, Fletcher and Hollis 1994, Ganey and Dick 1995, Gutierrez et al. 1995, Seamans and Gutierrez, 1995, and Ward et a1.1995). Mature mixed- conifer forests are mostly composed of Douglas - fir (Psuedotsuga menziesh), white fir (Abies concolor), limber pine (Pinus flexilis) or blue spruce (Picea pungens). Pine -oak forests are mostly composed of ponderosa pine (Pinus ponderosa) and Gambel oak (Quercus gambell1i). Riparian forests are dominated by various species of broadleaved deciduous trees and shrubs (Service 1995). These riparian forests can be important linkages between otherwise isolated subpopulations of owls (Service 1995). Owls are also found in canyon habitat dominated by vertical- walled rocky cliffs within complex watersheds including tributary side canyons. Rock walls include caves, ledges, and other areas that provide protected nest and roost sites (Gutierrez and Rinkevich 1991). Canyon habitat may include small isolated patches or stringers of forested vegetation including stands of mixed- conifer, ponderosa pine, pine - oak, pinyon - juniper, and /or riparian vegetation in which owls regularly roost and forage. Owls are usually found in areas with some type of water source (i.e., perennial stream, creeks, and springs, ephemeral water, small pools from runoff, reservoir emissions) (Gutierrez and Rinkevich 1991). Even small sources of water such as small pools or puddles create humid conditions (Geiger 1965 in Gutierrez and Rinkevich 1991). Owls are highly selective for roosting and nesting habitat, but forage in a wider array of habitats (Service 1995, Ganey and Balda 1994, and Seamans and Gutierrez 1995). Roosting and nesting habitat exhibit certain identifiable features, including large trees (those with a trunk diameter of 12 inches (in) (30.5 centimeters (cm)) or more (i.e. high tree basal area)), uneven- aged tree stands, multi- storied canopy, a tree canopy creating shade over 40 percent or more of the ground (i.e. moderate to high canopy closure), and decadence in the form of downed logs and snags (standing dead trees) (Ganey and Balda 1989; Ganey and Dick 1995; Grubb et al. 1997; Tarango et al. 1997; Peery et al. 1999; Ganey et al. 2000; and Geo - Marine 2004). Canopy closure is typically greater than 40 percent (Ganey and Balda 1989; Fletcher 1990; Zwank et al. 1994; Grubb et al. 1997; Tanrango et al. 1997; Ganey et al. 1998; Young et al. 1998; Ganey et al. 2000; and Geo - Marine 2004). All nests reported by Zwank et al. (1994), Seamans and Gutierrez (1995), and Geo- Marine (2004) were in either mixed- conifer or Douglas -fir habitat. Roost and nest trees were the oldest and largest within tree stands (Ganey and Balda 1989, 1994, and, Seamans and Gutierrez 1995). Owls use areas that contain a number of large trees of different types including mixed - conifer and pine -oak with smaller trees under the canopy of the larger trees. These types of areas provide vertical structure and high plant species richness that are important to owls. (FO) (Ganey and Dick 1995; Seamans and Gutierrez 1995; and Ganey et al. 2003). Tarango et al. (1994) and Ganey et al. (2000) recorded seven or more tree species at roost sites. Therefore, we believe that mixed- conifer dominated by Douglas -fir, pine -oak, and riparian forests with high tree diversity are important to the owl. Juvenile owls disperse in September and October, into a variety of habitats ranging from high - elevation forests to pinyon - juniper woodlands and riparian areas surrounded by desert grasslands (Gutierrez et al. 1995; Arsenault et al. 1997; and Willey and C. van Riper 2000). Observations of long - distance dispersal by juveniles provide evidence that they use widely spaced islands of suitable habitat which are connected at lower elevations by pinyon - juniper and riparian forests. As a result of these movement patterns, isolated populations may have genetic significance to the owl's conservation (Keitt et al. 1995; Guteirrez and Harrison 1996; Seamans et al. 1999; and Willey and C van Riper 2000). Owls have been observed moving across open low desert landscapes between islands of suitable breeding habitat (Arsenault et al. 1997; Ganey et al. 1998; and Willey 1998). Owl movements were also observed between "sky island" mountain ranges in New Mexico (Gutierrez et al. 1996). Therefore, contiguous stands or islands of suitable mixed - conifer, pine -oak, and riparian forests are important to the owl. Owl foraging habitat includes a wide variety of forest conditions, canyon bottoms, cliff faces, tops of canyon rims, and riparian areas (Gutierrez and Rinkevich 1991 and Willey 1993). Ganey and Balda (1994) reported that owls foraged more frequently in unlogged forests containing uneven- aged stands of Douglas -fir and white fir, with a strong component of ponderosa pine, than in managed forests. The primary owl prey species are woodrats , (Neotoma spp.), peromyscid mice (Peromyscus spp.), and microtine voles