Duane Diefenbach, PhD
Unit Leader - Pennsylvania Cooperative Fish and Wildlife Research Unit
Upon completion of his Ph.D., Duane worked for the Pennsylvania Game Commission as their biometrician for 7 years. There he began his current research involving grassland sparrows and black bears. Since 1999 he has been a research scientist with the Pennsylvania Unit and enjoys the challenges in integrating rese
Research Interests
Duane's primary research interests focus on empirically evaluating models used to estimate population parameters and how those models are incorporated in management decisions. Consequently, many of his research projects involve game species (white-tailed deer, black bear, and wild turkey). His research has focused on methods of estimating abundance as well as hunter attitudes and behavior and how that influences harvest rates and the spatial distribution of hunter harvest. Recent collaboration with the Pennsylvania Game Commission and DCNR Bureau of Forestry has involved the use of Structured Decision Making in developing management decision tools. Future research will likely work on integrating these tools in a quantitative manner into decision making processes.
However, not all his research involves game species. For over 10 years he has been studying grassland sparrows on reclaimed surface mines in Pennsylvania. There are several endangered and special concerns species that use reclaimed surface mines and he has focused on grasshopper, Savannah, and Henslow's sparrows because they are relatively abundant and are obligate grassland species. His research has focused on methods of estimating abundance and his students have addressed ecological issues related to their use of these habitats.
Teaching Interests
Duane teaches graduate courses in methods of estimating population parameters (WFS 560) and analyzing animal location data.
Professional Experience
Unit Leader, Pennsylvania Cooperative Fish and Wildlife Research Unit, 2007-
Assistant Unit Leader, Pennsylvania Cooperative Fish and Wildlife Research Unit, 1999-2007
Education and Certifications
Ph D University of Georgia 1992
MS University of Maine 1988
BS Washington State University 1985
Science and Products
Retention of riveted aluminum leg bands by wild turkeys
Evidence for range contraction of snowshoe hare in Pennsylvania
Population density influences dispersal in female white-tailed deer
Population and genetic outcomes 20 years after reintroducing bobcats (Lynx rufus) to Cumberland Island, Georgia USA
Can managers compensate for coyote predation of white-tailed deer?
Hidden Markov model for dependent mark loss and survival estimation
Mark-resight abundance estimation under incomplete identification of marked individuals
Setting objectives for managing Key deer
Occupancy patterns of regionally declining grassland sparrow populations in a forested Pennsylvania landscape
Habitat availability is a more plausible explanation than insecticide acute toxicity for U.S. grassland bird species declines
Effect of hunter selectivity on harvest rates of radio-collared white-tailed deer in Pennsylvania
Accounting for tagging-to-harvest mortality in a Brownie tag-recovery model by incorporating radio-telemetry data
Science and Products
- Publications
Filter Total Items: 67
Retention of riveted aluminum leg bands by wild turkeys
In order for mark–recapture models to provide unbiased estimates of population parameters, it is critical that uniquely identifying tags or marks are not lost. We double-banded male and female wild turkeys with aluminum rivet bands and estimated the probability that a bird would be recovered with both bands <1–225 wk since banding (mean = 51.2 wk, SD = 44.0). We found that 100% of females (n = 37)AuthorsDuane R. Diefenbach, Wendy C. Vreeland, Mary Jo Casalena, Michael V. SchiavoneEvidence for range contraction of snowshoe hare in Pennsylvania
In Pennsylvania, Lepus americanus (Snowshoe Hare) is near the southern limits of its range and at risk of range contraction because of loss of early-successional forest and impacts of climate change. We used hunter-harvest data to investigate changes in the distribution of Snowshoe Hare in Pennsylvania (1983–2011), forest inventory and land-use data to assess changes in amount and distribution ofAuthorsDuane R. Diefenbach, Stephen L. Rathbun, J.K. Vreeland, Deborah Grove, William J. KanapauxPopulation density influences dispersal in female white-tailed deer
Dispersal behavior in white-tailed deer (Odocoileus virginianus) predominantly occurs in 1-year-old males; however, females of the same age also disperse. The timing of female dispersal during fawning season and low dispersal rates suggest that competition for mates and reduced inbreeding are not ultimate causes of female dispersal, as suggested for males. We proposed that female dispersal is theAuthorsClayton L. Lutz, Duane R. Diefenbach, Christopher S. RosenberryPopulation and genetic outcomes 20 years after reintroducing bobcats (Lynx rufus) to Cumberland Island, Georgia USA
In 1988–1989, 32 bobcats Lynx rufus were reintroduced to Cumberland Island (CUIS), Georgia, USA, from which they had previously been extirpated. They were monitored intensively for 3 years immediately post-reintroduction, but no estimation of the size or genetic diversity of the population had been conducted in over 20 years since reintroduction. We returned to CUIS in 2012 to estimate abundance aAuthorsDuane R. Diefenbach, Leslie A. Hansen, Justin H. Bohling, Cassandra Miller-ButterworthCan managers compensate for coyote predation of white-tailed deer?
Many studies have documented that coyotes (Canis latrans) are the greatest source of natural mortality for white-tailed deer (Odocoileus virginianus) neonates (<3 months old). With the range expansion of coyotes eastward in North America, many stakeholders are concerned that coyote predation may be affecting deer populations adversely. We hypothesized that declines in neonate survival, perhaps cauAuthorsKelly F. Robinson, Duane R. Diefenbach, Angela K. Fuller, Jeremy E. Hurst, Christopher S. RosenberryHidden Markov model for dependent mark loss and survival estimation
Mark-recapture estimators assume no loss of marks to provide unbiased estimates of population parameters. We describe a hidden Markov model (HMM) framework that integrates a mark loss model with a Cormack–Jolly–Seber model for survival estimation. Mark loss can be estimated with single-marked animals as long as a sub-sample of animals has a permanent mark. Double-marking provides an estimate of maAuthorsJeffrey L. Laake, Devin S. Johnson, Duane R. Diefenbach, Mark A. TernentMark-resight abundance estimation under incomplete identification of marked individuals
Often less expensive and less invasive than conventional mark–recapture, so-called 'mark-resight' methods are popular in the estimation of population abundance. These methods are most often applied when a subset of the population of interest is marked (naturally or artificially), and non-invasive sighting data can be simultaneously collected for both marked and unmarked individuals. However, it caAuthorsBrett T. McClintock, Jason M. Hill, Lowell Fritz, Kathryn Chumbley, Katie Luxa, Duane R. DiefenbachSetting objectives for managing Key deer
The U.S. Fish and Wildlife Service (FWS) is responsible for the protection and management of Key deer (Odocoileus virginianus clavium) because the species is listed as Endangered under the Endangered Species Act (ESA). The purpose of the ESA is to protect and recover imperiled species and the ecosystems upon which they depend. There are a host of actions that could possibly be undertaken to recoveAuthorsDuane R. Diefenbach, Tyler Wagner, Glenn E. StaufferOccupancy patterns of regionally declining grassland sparrow populations in a forested Pennsylvania landscape
Organisms can be affected by processes in the surrounding landscape outside the boundary of habitat areas and by local vegetation characteristics. There is substantial interest in understanding how these processes affect populations of grassland birds, which have experienced substantial population declines. Much of our knowledge regarding patterns of occupancy and density stem from prairie systemsAuthorsJason M. Hill, Duane R. DiefenbachHabitat availability is a more plausible explanation than insecticide acute toxicity for U.S. grassland bird species declines
Grassland bird species have experienced substantial declines in North America. These declines have been largely attributed to habitat loss and degradation, especially from agricultural practices and intensification (the habitat-availability hypothesis). A recent analysis of North American Breeding Bird Survey (BBS) “grassland breeding” bird trends reported the surprising conclusion that insecticidAuthorsJason M. Hill, J. Franklin Egan, Glenn E. Stauffer, Duane R. DiefenbachEffect of hunter selectivity on harvest rates of radio-collared white-tailed deer in Pennsylvania
Radio transmitters are a commonly used tool for monitoring the fates of harvested species, although little research has been devoted to whether a visible radio transmitter changes a hunters' willingness to harvest that animal. We initially surveyed deer hunters to assess their willingness to harvest radio-collared deer and predicted radio collars were unlikely to affect the harvest of antlerless dAuthorsFrances E. Buderman, Duane R. Diefenbach, C.S. Rosenberry, Bret D. Wallingford, Eric S. LongAccounting for tagging-to-harvest mortality in a Brownie tag-recovery model by incorporating radio-telemetry data
The Brownie tag-recovery model is useful for estimating harvest rates but assumes all tagged individuals survive to the first hunting season; otherwise, mortality between time of tagging and the hunting season will cause the Brownie estimator to be negatively biased. Alternatively, fitting animals with radio transmitters can be used to accurately estimate harvest rate but may be more costly. We deAuthorsFrances E. Buderman, Duane R. Diefenbach, Mary Jo Casalena, Christopher S. Rosenberry, Bret D. Wallingford - Science