/ We propose a foraging guild classification for North American inland, coastal, and pelagic birds. This classification uses a three-part identification for each guild--major food, feeding substrate, and foraging technique--to classify 672 species of birds in both the breeding and nonbreeding seasons. We have attempted to group species that use similar resources in similar ways. Researchers have identified foraging guilds generally by examining species distributions along one or more defined environmental axes. Such studies frequently result in species with several guild designations. While the continuance of these studies is important, to accurately describe species' functional roles, managers need methods to consider many species simultaneously when trying to determine the impacts of habitat alteration. Thus, we present an avian foraging classification as a starting point for further discussion to aid those faced with the task of describing community effects of habitat change.Many approaches have been taken to describe bird feeding behavior. Comparisons between different studies, however, have been difficult because of differences in terminology. We propose to establish a classification scheme for North American birds by using common terminology based on major food type, substrate, and technique, using foraging guilds.The guild concept was originally proposed by Root (1967) to indicate a group of species that exploit the same class of environmental resources in a similar way. For example, Root defined a foliage-gleaning guild in oak woodlands as a group of birds whose diet consisted of arthropods obtained from the foliage zone of oaks. Root pointed out that birds could be a member of several guilds. Thus, seasonal changes that occur in avian feeding habitats could be accommodated. The guild concept has become a useful tool in looking at competition, niche separation, and functional relationships within the community. As a result, biologists can use the guild concept to show how different taxa interrelate and how impacts of habitat change influence community dynamics and not just individual species.The guild concept has been used by a number of authors to compare or classify components of a community. It is possible to establish guilds on the bases of different criteria. Landres (1983) reviews some efforts to assign species to guilds. Guilds were used by Severinghaus (1981) to develop the idea of indicator species; he believed that since all members use the same resource, all should respond similarly to changes in their environment. There are enough exceptions, in part because Severinghaus's guilds were not all ba~cd on habitat requirements, to question whether the indicator concept would be effective.Thomas and others (1979) developed lists of species by life form for each habitat and successional stage in the Blue Mountains of Oregon. This is a use of the guild concept in which assemblages of species are defined according to common nesting and feeding requirements. Another use of the guild concept was...

Nesting habitat degradation and its negative effect on nesting success might contribute to the recent population and distributional declines of greater sage-grouse (Centrocercus urophasianus) throughout North America. We used radiotelemetry to locate greater sage-grouse nests in 7 different areas of central and southwestern Wyoming between 1994 and 2002; we studied each area for 2 to 4 years. Using binary logistic regression, we compared microsite vegetal data collected at nests (n = 457) and random (n = 563) sites and successful (n = 211) and unsuccessful (n = 238) nests to test hypotheses concerning greater sage-grouse nesting habitat selection and vegetal conditions associated with nesting success. We used Akaike's Information Criterion (AIC c ) and model averaging to make inference about the weighted support for the importance of individual habitat variables through the comparison of sets of competing models. Selected nest sites were located in areas with increased total shrub canopy cover (relative importance [RI] = 1.00), residual grass cover (RI = 0.47), and residual grass height (RI = 0.77) compared to random sites. Successful nests had increased residual grass cover (RI = 0.43) and height (RI = 0.48) relative to unsuccessful nests. Additionally, annual nest success rates (i.e., above vs. below our study's average) were related to the preceding year's spring (Apr-May; RI = 0.44) and winter-early spring (Jan-Jun) precipitation (RI = 0.32). Correct classification rates for weighted average models that we derived through the 3 comparisons were between 60 and 70%, suggesting the variables adequately differentiated between plot types. However, high model selection uncertainty (i.e., the total number of models included in the sets of AIC c -selected models) suggested that nest site selection and nesting success may be influenced by factors not considered in the modeling process. Management strategies that protect dense sagebrush stands and enhance residual grass cover and height within those stands should be used to maintain nesting habitat and increase nesting success of greater sage-grouse. JOURNAL OF WILDLIFE MANAGEMENT 69(2):638-649; 2005

Two methods of estimating small—mammal population size from multiple capture—mark—recapture occasions, the Lincoln—Petersen estimator and program CAPTURE, were evaluated and compared using computer simulation. Comparisons were made for population sizes of 50, 75, and 100, trapping periods of 5, 7, and 10 d and numerous patterns of capture probabilities. Program CAPTURE often failed to provide useful estimates of population size due to the poor performance of its model selection procedure. The Lincoln—Petersen estimator provides estimates of population size with low biases and standard errors except when uniform behavioral response occurs or when there is high heterogeneity in individual capture probabilities. We suggest that researchers use CAPTURE as a screening technique to check for evidence of uniform trap responses and/or high individual heterogeneity in capture probabilities. If these influences are not present, the Lincoln—Petersen estimator may be the best method for estimation of small—mammal population size.

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Bird populations were sampled between May 30 and July 20, 1972, on twenty—four 0.08—ha plots on Walker Branch Watershed, a primarily deciduous forest located in Anderson County, Tennessee. Univariate analysis of variance was used to test for differences in abundance categories of each bird species with respect to 28 habitat variables. Differences in habitat preferences within major bird families (Picidae, Parulidae, Paridae, and Thraupidae) were apparent from this analysis. Discriminant function analysis was therefore used to order the variables according to their strength in separating abundance categories for 13 of the more abundant bird species. This analysis indicated that some bird species were distributed according to specific habitat variables. For example, Downy Woodpecker abundance was highly correlated with the number of saplings on a plot. Distributions of other species (e.g., the Scarlet Tanager) were not strongly related to any single variable but were related weakly to a large number of variables. The results form a basis for predicting avifaunal composition changes resulting from alteration of habitat structure.