We assessed diet of spotted bats ( Euderma maculatum (J.A. Allen, 1891)) by visual analysis of bat feces and stable carbon (δ13C) and nitrogen (δ15N) isotope analysis of bat feces, wing, hair, and insect prey. We collected 33 fecal samples from spotted bats and trapped 3755 insects where bats foraged. Lepidopterans averaged 99.6% of feces by volume; other insects were not a major component of diet. The δ13C and δ15N values of bat feces were similar to those of moths from families Noctuidae (N), Lasiocampidae (L), and Geometridae (G), but differed from Arctiidae (A) and Sphingidae (S). We used a mixing model to reconstruct diet; three families (N, L, G) represented the majority (88%–100%) of the diet with A + S representing 0%–12%. Although we compared δ13C and δ15N values of wing, hair, and feces of spotted bats, feces best represented recent diet; wing and hair were more enriched than feces by 3‰ and 6‰, respectively. This pattern was consistent with that reported for other bat species. We suggest that spotted bats persist across a wide latitudinal gradient partly because they can forage on a variety of noctuid, geometrid, and lasiocampid moths. Using visual fecal inspection with stable isotope analysis provided information on families of moths consumed by an uncommon bat species.
In montane forests of the western United States, a general correlation of accipiter body size and scaling of the vegetation component of nesting sites and nest trees used by sympatric Accipiter species has been reported. We evaluated this pattern with vegetation data collected at Northern Goshawk (Accipiter gentilis), Cooper' s Hawk (A. cooper@, and Sharp-shinned Hawk (A. striatus) nest sites in the Jemez Mountains and Pajarito ,Plateau of north-central New Mexico. We selected habitat variables at the nest tree and nest site scale that would allow us to evaluate the prediction that accipiters use nesting habitat in which their body size is positively correlated with tree size and tree spacing, and inversely correlated with tree density, basal area, and percent canopy closure. At the nest-site level, density of larger diameter trees should be positively correlated with body size, and density of smaller diameter trees should be inversely correlated with body size. Our results suggest that nest tree height and diameter support body size predictions about nesting habitat for accipiter hawks. None of the nest-site parameters measured in this study supported the body size predictions due to a large amount of intra-specific variation. As a result of this variation, it was difficult to differentiate between Cooper' s Hawk and Northern Goshawk nest sites for most site variables. These results suggest there is a correlation between accipiter size and nest tree size, but that a correlation between nest site structural size and accipiter body size may not be a widespread phenomenon for all vegetation variables for all three species. Many commonly measured forest stand structural characteristics such as basal area and total tree densities may not be adequate for predicting suitable accipiter nesting habitat in all areas, particularly in the absence of comparisons with available habitat.
Lek disturbance buffers can be used to identify areas that provide important seasonal habitat for Gunnison sage grouse Centrocercus minimus (hereafter GUSG), a species with declining or vulnerable populations across their range. Lek disturbance buffers define areas around leks where anthropogenic disturbance is not permitted and have been considered for potential conservation strategies across GUSG habitat. Currently there is minimal information available on the effectiveness of the size of defined lek disturbance buffers. This study focused on two GUSG populations, the smaller Crawford population and a segment of the larger Gunnison Basin population. We utilized global positioning system location data on GUSG to evaluate seasonal use within three lek disturbance buffers, then compared and contrasted results between the two populations. The Crawford GUSG population showed increased movements from breeding season to late brood-rearing season and in winter returned to a usage pattern similar to the breeding season. Comparatively, the western Gunnison Basin GUSG population showed considerable movement throughout the entire year. In addition to these differences, we noted remarkable differences in distance between active leks, home range size, and total daily distance traveled between Crawford and western Gunnison Basin populations. Lek disturbance buffers created using the standard protocol provided varying protection depending on the distance between leks and number of leks. In small populations, the disturbance buffers overlapped each other, thus producing a smaller total lek disturbance buffer area. In addition to adding to the general body of knowledge of a little-studied species, our study had two important findings: 1) the use of empirical cumulative distribution demonstrated considerable differences in lek disturbance buffer use between the Crawford and the western Gunnison Basin populations, and 2) lek disturbance buffers did not provide equal protection for all populations on the basis of their current definition and derivation. We anticipate that land managers will find our results useful and informative when developing land management plans for the conservation of GUSG. Our analysis showed that the variability between populations and species is important for managers to consider when developing conservation strategies, especially for small populations.
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