Geology topics

K. S. Laves

Publications and source records attributed to K. S. Laves.

2 recordsLinked to original sources

USGS2006

Effects of southern flying squirrels Glaucomys volans on red-cockaded woodpecker Picoides borealis reproductive success

Anecdotal data gathered from many populations suggest that southern flying squirrel (SFS, Glaucomys volans ) use of the endangered red-cockaded woodpecker's (RCW, Picoides borealis ) nest and roost cavities may negatively affect RCW populations. We conducted a controlled experiment to determine the effects of SFSs on RCW reproductive success. During the 1994 and 1995 breeding seasons, SFSs were removed from 30 RCW clusters and 32 clusters served as controls. SFSs were the most frequently encountered occupants of RCW cavities and used 20–33% of RCW cavities in control and treatment clusters over both years. Treatment groups produced significantly more successful nests (≥ 1 fledgling) than control groups in 1994. In 1995 however, there was no difference in the number of successful nests. In both years, RCW groups nesting in treatment clusters produced significantly more fledglings than groups in control clusters in each of four experimental areas, averaging approximately 0.7 additional fledglings per nesting group. Loss of entire clutches or broods, possibly as a result of predation or abandonment, was a major factor limiting reproduction in control groups in 1994. In contrast, differences in partial brood loss appeared to be the cause of differential fledging success in 1995. Usurpation of RCW roost cavities by SFSs may have placed greater energetic demands on RCWs for cavity defence or thermoregulation, thus reducing energy available for reproduction. Our results show that SFS use of RCW cavities during the breeding season has a significant impact on RCWs and that management of RCW populations should include activities that either minimize SFS populations in RCW clusters or limit access of SFSs to RCW cavities.

Animal Conservation↗

USGS2006

Differential estimates of southern flying squirrel (Glaucomys volans) population structure based on capture method

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.

American Midland Naturalist↗