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Geology topics

D.F. Stauffer

Publications and source records attributed to D.F. Stauffer.

3 recordsLinked to original sources

Evaluation of a habitat suitability index model

We assisted with development of a model for maternity habitat of the Indiana bat (Myotis soda/is), for use in conducting assessments of projects potentially impacting this endangered species. We started with an existing model, modified that model in a workshop, and evaluated the revised model, using data previously collected by others. Our analyses showed that higher indices of habitat suitability were associated with sites where Indiana bats were present and, thus, the model may be useful for identifying suitable habitat. Utility of the model, however, was based on a single component-density of suitable roost trees. Percentage of landscape in forest did not allow differentiation between sites occupied and not occupied by Indiana bats. Moreover, in spite of a general opinion by participants in the workshop that bodies of water were highly productive feeding areas and that a diversity of feeding habitats was optimal, we found no evidence to support either hypothesis.

Conference Paper

Buteos

Red-tailed, red-shouldered, and broad-winged hawks nest throughout the 11 northeastern states, and red-tailed, red-shouldered, and rough-legged hawks winter in this region. Historical and present ranges of these species are similar, although red-shouldered and broad-winged hawk ranges now have more vacant patches at a local and regional level. Only the red-shouldered hawk is of special concern or officially listed as threatened by some state agencies. Analysis of Breeding Bird Survey (BBS) data indicated positive trends in counts of red-tailed hawks along the more developed Northeast corridor. No trends were found in analyses of BBS data for red-shouldered hawks in either more- or less-developed regions of the Northeast. Based on the BBS, we found a decreasing trend in counts of broad-winged hawks along the more-developed Northeast corridor, and an increasing trend in less-developed regions of the Northeast. Our analyses of Christmas Bird Count data indicated no trend in counts of red-shouldered nor rough-legged hawks, but an increase in counts of red-tailed hawks from 1962 to 1983. Many individuals believe that species such as the red-shouldered hawk are declining in the Northeast, but no trends were detected in our analyses.

Book chapter