Nicholas R. Holler

Enhancing Bachman's sparrow habitat via management of red-cockaded woodpeckers

Bachmans sparrows (Aimophila aestivalis) and red-cockaded woodpeckers (Picoides borealis) use mature pine woodlands characterized by well-spaced pines, an open midstory, and a dense understory of grasses and forbs. Populations of the Bachmans sparrow began declining in the 1930s, with both a dramatic retraction in geographic distribution and the extinction of many local populations. Current land management practices in the southeastern United States often focus on the habitat requirements of the red-cockaded woodpecker without considering other species with similar habitat requirements (i.e., Bachmans sparrow). We examined habitat requirements of the Bachmans sparrow on Eglin Air Force Base, Florida, to determine if management practices directed at recovery of red-cockaded woodpeckers are providing Bachmans sparrows with suitable habitat. Comparisons between active red-cockaded woodpecker clusters occupied (n = 8) and unoccupied (n = 13) by Bachmans sparrows showed that Bachmans sparrows selected areas with a dense understory of grasses and sparse midstory vegetation. Areas suitable for red-cockaded woodpeckers were not always suitable for Bachmans sparrows. Red-cockaded woodpeckers appear more tolerant of a hardwood midstory and do not require a dense cover of grasses and forbs. Prescribed burning is key for development and maintenance of the dense herbaceous understory preferred by Bachmans sparrow. In areas managed for red-cockaded woodpeckers, frequent (3-5 yr) burning early in the growing season appears the best way to increase habitat suitability for Bachmans sparrows.

Habitat use and relative abundance of gray squirrels in southern Alabama

We studied habitat use and estimated relative abundance of gray squirrels (Sciurus carolinensis) in 3 habitats at the Solon Dixon Forestry Education Center, Covington and Escambia counties in southern Alabama, from January 1987 to September 1988. Three representative stands of even-aged pine, mixed pine-hardwood, and hardwood were selected for study, and a 50-station trapping grid was established in each. We captured 603 squirrels 1,586 times. Relative abundance was based on the minimum number of squirrels known alive. Squirrel abundance in hardwood and in mixed pine-hardwood habitat did not differ (P=0.47), but abundance in even-aged pine was lower (P<0.001) than either of the other 2 habitats. We measured 6 habitat variables in each study area. Moderately open understories with a dense shrub crown (vegetation between 1 and 5 m) component appear to be important to squirrel abundance. To determine habitat preference, we fitted 17 gray squirrels with radio transmitters. Narrow bands of hardwoods along ephemeral streams (i.e., hardwood stringers) were an important component of gray squirrel habitat in even-aged pine and mixed pine-hardwood stands. Forest management should include the retention of hardwood stringers within pine and mixed pine-hardwood stands

Population Dynamics of Beach Mice (Peromyscus polionotus ammobates) in Southern Alabama

Population dynamics of Alabama beach mice ( Peromyscus polionotus ammobates ) were studied at two sites (Perdue and Ft. Morgan) on Bon Secour National Wildlife Refuge, Baldwin Co., Alabama, from January 1987 to November 1989; 997 mice were marked and released. Closed population models (program CAPTURE) and minimum number of mice known alive were used to obtain population indices; open population models (program JOLLY) were used to estimate survival probabilities. Population numbers fluctuated seasonally, with mice most abundant in winter and spring. Sex ratios neither varied seasonally nor differed from 1:1, although numerically more males than females were captured in 19 of 24 trapping periods. Percentage of subadults was highest in winter and lowest in summer, whereas percentage of reproductively active females was highest in autumn and winter and lowest in summer. Mean body mass of adult mice did not vary seasonally; females weighed more than males during the winter.

Potential Secondary Hazards of Avitrol Baits to Sharp-Shinned Hawks and American Kestrels

18pp. MARTIN, L. R., AND J. J. JACKSON. 1977. Field testing a bird repellent chemical on cereal crops. Pages 177-185 in J. R. Beck, ed. Vertebrate pest control and management materials. Am. Soc. Test. Mater. ASTM STP 680. SCHAFER, E. W., JR., AND R. B. BRUNTON. 1971. Chemicals as bird repellents: two promising agents. J. Wildl. Manage. 35:569-572. , R. B. BRUNTON, N. F. LOCKYER, AND J. W. DE GRAZIO. 1973. Comparative toxicity of seventeen pesticides to the quelea, house sparrow, and red-winged blackbird. Toxicol. Appl. Pharmacol. 26:154-157.

Simulation of cotton rat population dynamics and response to rodenticide applications in Florida sugarcane

Abstract Alternative deterministic simulation models were compared to test the management consequences of present uncertainty about the degree of density dependence involved in cotton rat population cycles in southern Florida sugarcane fields. Efficacy of rodenticide applied in different months was explored under six different scenarios of density dependence and independence in two population parameters: fecundity and juvenile survival. Output from the six models differed considerably in the number of rats produced, but was remarkably consistent in the most effective months to apply rodenticide. Since models without density-dependent fecundity were inherently unstable and an inverse relationship between fecundity and population size is apparent in field data, such a population-growth mechanism seems possible in Florida sugarcane fields. The model in which fecundity was density-dependent at all times produced rat densities closest to field data. Output from this model was most sensitive to changes in the amount litter size declines as population size increases. Field tests are necessary to validate the general agreement among the models about the most effective months to apply rodenticide.