Susan C. Loeb

Responses of Small Mammals to Coarse Woody Debris in a Southeastern Pine Forest

The importance of coarse woody debris (CWD) to small mammals in a managed pine forest in South Carolina was tested experimentally during summer and autumn 1990 and winter and spring 1991–1994. Abundance and demographics of small mammals were compared between plots with abundant CWD created by a tornado (unsalvaged plots) and plots where tornado-created CWD had been removed (salvaged plots). Species composition was similar between unsalvaged and salvaged plots, but more small mammals were captured on unsalvaged plots. Cotton mice ( Peromyscus gossypinus ) were the most abundant species captured in all plots and were significantly more abundant in unsalvaged plots in every trapping period. Adult female P. gossypinus in unsalvaged plots had greater survival and were more likely to be in reproductive condition than adult females in salvaged plots. Southern short-tailed shrews ( Blarina carolinensis ) and cotton rats ( Sigmodon hispidas ) tended to be more abundant in unsalvaged plots. Fox squirrels ( Sciurus niger ), the second most abundant species in salvaged plots, were never captured on unsalvaged plots. Large amounts of CWD improve habitat quality of pine forests for P. gossypinus , and CWD is probably an important habitat component for other species.

INDIANA BAT, MYOTIS SODALIS, MATERNITY ROOSTS IN THE SOUTHERN UNITED STATES

Abstract We characterized Indiana bat (Myotis sodalis) roosting habitat at three maternity colony sites in western North Carolina and eastern Tennessee. Using radio telemetry, we tracked six bats a total of 40 bat days (range 4–9 days/bat). In 1999, we located a primary roost in an eastern hemlock (Tsuga canadensis) snag (109 cm DBH) in the Nantahala National Forest, NC. In 2000, we located a primary roost in a pine (Pinus sp.) snag (39 cm DBH) in Great Smoky Mountains National Park (GSMNP), TN. Another primary roost was found in a pitch pine snag (P. rigida; 55 cm DBH) in GSMNP in 2001. Largest exit counts for the three colonies were 28, 23, and 81 bats. Primary roost sites were exposed to direct sunlight during most of the day. We also located six alternate roost trees: three pine snags, two red oak (Quercus rubra) snags, and one live sweet birch (Betula lenta). All three primary roosts located in this study were not used during subsequent summers. The eastern hemlock used in 1999 was still standing as of June 2001, while the two primary roosts in GSMNP had fallen within a year of being located. These records represent one of the first descriptions of Indiana bat maternity habitat in the southern United States.

Use and Selection of Red-Cockaded Woodpecker Cavities by Southern Flying Squirrels

Southern flying squirrels (Glaucomys volans) may have a negative impact on red-cock woodpeckers (RCWs, Picoides borealis). Thus, I examined cavities excavated by RCWs in central Georgia during 4 breeding seasons to determine the extent of cavity use by southern flying squirrels and other competitors, and to determine whether flying squirrels select cavities on the basis of cavity or tree characteristics. Species other than RCWs occupied 18-25% of the RCW cavities over the 4 years. Flying squirrels used 10-21% of RCW cavities, whereas avian species other than RCWs used 4-8% of the cavities. Flying squirrels selected cavities primarily on the basis of cavity entrance size. Entrances to cavities used by flying squirrels were smaller (P ≤ 0.05) than entrances to unused cavities, and squirrels strongly preferred (P ≤ 0.05) cavities that had not been enlarged

Using Hydrogen Isotopes to Assign Origins of Bats in the Eastern United States

Abstract Stable hydrogen isotopes (δDs) in metabolically inert tissues such as feathers and hair provide a set of endogenous markers that may be useful for establishing migratory connectivity in animals. We tested the assumption of a clear relationship between δD values of growing-season–weighted average precipitation (δDp) derived from 2 geographic information system (GIS) models or latitude (LAT) and δD values in bat hair (δDh), and examined intra- and interspecific variation in δDh of 4 bat species in the eastern United States. We analyzed 251 hair samples from 1 long-distance migrant (eastern red bat [Lasiurus borealis]) and 3 regional migrants (Indiana bat [Myotis sodalis], northern long-eared bat [M. septentrionalis], and little brown bat [M. lucifugus]) captured during the reproductive period (pregnancy and lactation) when bats are resident. LAT explained more of the variation in δDh than δDp derived from either of the GIS-based models, although 1 model of δDp performed better for some species. We found significant intraspecific differences in the relationships between δDh and LAT and between δDh and estimates of δDp derived from Bowen et al. (δDpB) for L. borealis, and significant variation in the regression equations of δDh and LAT and δDh and δDp among species for adult females and adult males. Stable hydrogen isotope analysis may be a valuable tool for studying migratory connectivity in bats, but significant intra- and interspecific variation in δDh values suggests that pooling across sex and age categories and use of surrogate species should be avoided.

Effects of Orientation and Weatherproofing on the Detection of Bat Echolocation Calls

Abstract Ultrasonic detectors are powerful tools for the study of bat ecology. Many options are available for deploying acoustic detectors including various weatherproofing designs and microphone o...

An experimental test of interspecific competition for red-cockaded woodpecker cavities

To test whether the presence of nest boxes near red-cockaded woodpecker (RCW, Picoides borealis) cavity trees reduced cavity use by other species and improved RCW reproductive success on the Francis Marion National Forest in coastal South Carolina, we placed 3 nest boxes in each of 62 experimental clusters and designated 61 clusters as controls. Our observations of nest box and cavity use showed that nest boxes were somewhat effective in reducing cavity use and that eastern bluebirds (Sialia sialis) and southern flying squirrels (Glaucomys volans) were the most frequent users of nest boxes and cavities. Bluebirds preferred nest boxes to cavities in both years and flying squirrels showed significant preference for nest boxes in 1992. Pretreatment monitoring (1990) of RCW reproductive performance showed no significant differences between control and experimental groups. However, posttreatment monitoring showed that in 1991 RCWs in experimental clusters were significantly more likely to nest than RCWs in control clusters; in 1991 and 1992, they were more likely to fledge ≥1 young. Further, RCWs were less likely to initiate a nest if≥1 cavity was occupied by a non-RCW species than if no cavities in the cluster were occupied by a non-RCW species. These results indicate that RCW cavities were subject to interspecific competition and that nest boxes may be an effective means of reducing competition, particularly when the number of cavities is limited.

Diet of nestling red-cockaded woodpeckers at three locations.

Abstract We conducted a 2-yr study of the nestling diet of Red-cockaded Woodpeckers (Picoides borealis) at three locations to determine how it varied among sites. We photographed 5939 nest visits by adult woodpeckers delivering food items for nestlings. In 1994, we located cameras near three nest cavities on the Lower Coastal Plain of South Carolina and near two cavities at the Savannah River Site, which is on the Upper Coastal Plain. In 1995, cameras were installed on the Savannah River Site and in the Piedmont National Wildlife Refuge, Georgia. The cameras recorded adults bringing 33 different types of food to nestlings. Wood roaches (Blattoidea: Blattellidae, Parcoblatta spp.) were the most common food composing 50% of the diet overall. They were also the most common prey at each location and for all but one of the woodpecker groups studied. Wood roaches were recorded in 26% of the visits photographed on the Lower Coastal Plain and 62% of the nest visits on the Upper Coastal Plain in 1994. In 1995, wood roaches were recorded in 57% and 50% of the visits on the Upper Coastal Plain and Piedmont, respectively. Woodpeckers on the Lower Coastal Plain used blueberries (Vaccinum sp.) and sawfly larvae (Hymenoptera: Diprionidae, Neodiprion sp.), two dietary items not commonly used at the other locations. Adults at two locations providing snail shells to nestlings possibly as an additional source of calcium. Moristas index of diet overlap (C) ranged from 0.94 to 0.99 for breeding males and females in the same group, from 0.63 to 0.99 among groups at the same location, and from 0.68 to 0.96 among locations. Because diet overlap of Red-cockaded Woodpecker nestlings at different geographical locations was within the range that occurred among groups at the same location, we conclude that nestling diets are similar across the geographical area studied, and that it varies little from year to year.

Ground-Dwelling Arthropod Association with Coarse Woody Debris Following Long-Term Dormant Season Prescribed Burning in the Longleaf Pine Flatwoods of North Florida

ABSTRACT A 5-year study of long-term (40 years) study plots was conducted on the Osceola National Forest in northern Florida to determine how dormant-season fire frequency (annual, biennial, quadrennial, or unburned) affects ground-dwelling macroarthropod use of coarse woody debris in longleaf pine (Pinus palustris Mill.) forests. Pitfall traps were used to sample arthropods near logs or metal drift fences of equal length. Samples were identified to genus or the lowest practical taxonomic level. Overall, significantly more arthropods and more arthropod biomass were captured near drift fences than near logs. Similarity of arthropods captured near logs or drift fences ranged from 64.4% in annually burned plots to 69.2% in quadrennially burned plots, with no significant differences noted. Likewise, Shannon diversity, evenness, richness, and number of rare genera were the same for traps regardless of the trap location. Interaction between fires and trap location were observed in 31 of 932 arthropod taxa. Of those, 10 taxa had significantly higher numbers captured in traps near logs in some burn treatments but there was no consistent pattern between log use and fire frequency. In most cases, more were captured in log pitfalls in frequently burned plots but that was not the case for at least 4 taxa. Where interactions between trap location and fire frequency were not significant, arthropods in an additional 101 taxa were captured in higher numbers at 1 trap location or the other. Of those, 73 were captured in higher numbers in pitfalls near drift fences and 28 were captured in higher numbers near logs. Results showed no increase in log usage by general or more mobile ground-dwelling arthropods as more frequent burning reduced the herbaceous and woody under story. However, logs were clearly important to a wide variety of arthropods regardless of burn frequency.

The role of fish, wildlife and plant research in ecosystem management

This paper examines the concepts of ecology, ecosystems, and ecosystem management and then further examines the role of fish, wildlife, and plant ecology research in ecosystem management, past, present, and future. It is often assumed that research in support of ecosystem management will entail comprehensive studies of entire ecosystems whereas research programs that focus on one species do not constitute ecosystem management level research. The supposed dichotomy between single species and ecosystem level approaches has been the focus of considerable debate. However, this is a false dichotomy and ecosystem studies and single-species studies simply represent two ends of a spectrum of approaches for understanding ecological processes. Given that the level of scientific investigation (e.g., individual species, community, or ecosystem) does not differentiate ecosystem management research from more traditional approaches, what are the distinguishing features? Ecosystem management research is broader in scope than more traditional ecological studies. A greater emphasis is also placed on integrating results of various studies and programs to understand larger scale interactions and the structure and function of ecosystems. Model building also plays a greater role in ecosystem management research efforts as a means of not only understanding ecosystem processes but also as a means of generating hypotheses. Although the primary responsibilities of research and management are different, there is much room for interaction and integration of functions. Consequently, adaptive management has become an important part of ecosystem management and will likely become a larger part of basic research programs. However, adaptive management experiments should not be the endpoint. Instead, results from adaptive management studies should be used to generate hypotheses that can be tested with more traditional and rigorous scientific methods. As managers begin to deal at larger spatial and longer temporal scales changes in the end-products of research will be necessary. The task of assessing present as well as future conditions will greatly increase the need for user-friendly analytical tools (e.g., simulation models) that allow managers to visualize conditions on a large scale. A balance of adaptive management and traditional experimental designs will ultimately lead to better models of management.

Differential Estimates of Southern Flying Squirrel (Glaucomys volans) Population Structure Based on Capture Method

Abstract It is commonly assumed that population estimates derived from trapping small mammals are accurate and unbiased or that estimates derived from different capture methods are comparable. We captured southern flying squirrels (Glaucomys volans) using two methods to study their effect on red-cockaded woodpecker (Picoides borealis) reproductive success. Southern flying squirrels were captured at and removed from 30 red-cockaded woodpecker cluster sites during March to July 1994 and 1995 using Sherman traps placed in a grid encompassing a red-cockaded woodpecker nest tree and by hand from red-cockaded woodpecker cavities. Totals of 195 (1994) and 190 (1995) red-cockaded woodpecker cavities were examined at least three times each year. Trappability of southern flying squirrels in Sherman traps was significantly greater in 1995 (1.18%; 22,384 trap nights) than in 1994 (0.42%; 20,384 trap nights), and capture rate of southern flying squirrels in cavities was significantly greater in 1994 (22.7%; 502 cavity inspections) than in 1995 (10.8%; 555 cavity inspections). However, more southern flying squirrels were captured per cavity inspection than per Sherman trap night in both years. Male southern flying squirrels were more likely to be captured from cavities than in Sherman traps in 1994, but not in 1995. Both male and female juveniles were more likely to be captured in cavities than in traps in both years. In 1994 males in reproductive condition were more likely to be captured in cavities than in traps and in 1995 we captured significantly more reproductive females in cavities than in traps. Our data suggest that population estimates based solely on one trapping method may not represent true population size or structure of southern flying squirrels.