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I measured characteristics of vegetation around middens of the endangered Mount Graham red squirrel (Tamiasciurus hudsonicus grahamensis) in the Pinaleno Mountains of southeastern Arizona. Midden sites were compared to random sites in both the spruce/fir and transition-zone forests. Foliage volume, canopy closure over plot center, volume of downed logs ≥20 cm in diameter, and density of snags >40 cm in diameter at breast height (dbh) were greater at midden sites and best distinguished midden sites from random sites in both forest types. The mean stand age of midden sites was >230 years in the spruce/fir forest and >200 years in the transition-zone forest. As regeneration of disturbed sites will take long periods of time, management applications to protect the red squirrel must focus on preserving existing habitat by limiting activities that remove large trees, snags, or logs, open the forest canopy, create forest edge, or otherwise disrupt forest integrity.

I quantified several aspects of hibernacula use and estimated home ranges of desert tortoises (Gopherus agassizii) in the San Pedro Valley, Arizona. Tortoises hibernated primarily on steep southerly slopes. Hibernacula included burrows in silt, silt with loose gravel, diatomite and/or diatomaceous marl, and beneath an ash layer, often in conjunction with live vegetation, dead and downed vegetation, and packrat (Neotoma albigula) nests. Male tortoises used longer hibernacula than females (p < 0.02). Female maximum hibernacula temperatures were consistently higher than male maximum hibernacula temperatures, but the difference was not significant (0.05 < p < 0.10). Female minimum hibernacula temperatures were significantly lower than males (p < 0.001) and female hibernacula temperatures fluctuated over a significantly wider temperature range than males (p < 0.01). Hibernacula used by males provided greater thermal buffering than those used by females. Duration of hibernation was positively correlated with shelter length. Home-range estimates did not differ significantly between males and females.

I radio-tagged and followed 5 and 9 male Northern Goshawks (Accipiter gentilis atricapillus) during the breeding seasons of 1991 and 1992, respectively, to evaluate their use of different forest conditions in managed ponderosa pine (Pinus ponderosa) forests. Sufficient data for habitat analyses were collected for 11 birds. Minimum convex polygon home-ranges averaged 1,758 ha (SD = 500 ha, range 896-2528 ha) and harmonic mean home ranges averaged 1,530 ha (SD = 477 ha, range 859-2,321 ha). I compared use (i.e., number of hawk locations) and availability (i.e., % of area of home range) for three different forest conditions (canopy closure, edge, and diversity) generated from LANDSAT data. Most (&ge;6) of the 11 birds used the categories in the three overlays in proportion to their availability. Six of the 11 birds used at least one category on one of the overlays nonrandomly. When the categories of canopy closure were ranked for each bird on the basis of relative preference, these ranks increased with increasing canopy closure.

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