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
Loss of butt-end leg bands on male wild turkeys
An evaluation of sex-age-kill (SAK) model performance
Estimating avian population size using Bowden's estimator
Movement and habitat use of sika and white-tailed deer on Assateague Island National Seashore, Maryland
Modeling distribution of dispersal distances in male white-tailed deer
Multiple proximate and ultimate causes of natal dispersal in white-tailed deer
Deer hunting on Pennsylvania's public and private lands: A two-tiered system of hunters?
Incorporating availability for detection in estimates of bird abundance
Spatial organization of a reintroduced population of bobcats
Controlling for anthropogenically induced atmospheric variation in stable carbon isotope studies
Forest cover influences dispersal distance of white-tailed deer
Annual survival estimation of migratory songbirds confounded by incomplete breeding site-fidelity: Study designs that may help
Science and Products
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Filter Total Items: 67
Loss of butt-end leg bands on male wild turkeys
We estimated loss of butt-end leg bands on male wild turkeys (Meleagris gallapavo) captured in New York, Ohio, and Pennsylvania (USA) during December–March, 2006–2008. We used aluminum rivet leg bands as permanent marks to estimate loss of regular aluminum, enameled aluminum, anodized aluminum, and stainless steel butt-end leg bands placed below the spur. We used band loss information from 887 turAuthorsDuane R. Diefenbach, Mary Jo Casalena, Michael V. Schiavone, David A. Swanson, Michael Reynolds, Robert C. Boyd, Robert Eriksen, Bryan L. SwiftAn evaluation of sex-age-kill (SAK) model performance
The sex-age-kill (SAK) model is widely used to estimate abundance of harvested large mammals, including white-tailed deer (Odocoileus virginianus). Despite a long history of use, few formal evaluations of SAK performance exist. We investigated how violations of the stable age distribution and stationary population assumption, changes to male or female harvest, stochastic effects (i.e., random flucAuthorsJoshua J. Millspaugh, John R. Skalski, Richard L. Townsend, Duane R. Diefenbach, Mark S. Boyce, Lonnie P. Hansen, Kent KammermeyerEstimating avian population size using Bowden's estimator
Avian researchers often uniquely mark birds, and multiple estimators could be used to estimate population size using individually identified birds. However, most estimators of population size require that all sightings of marked birds be uniquely identified, and many assume homogeneous detection probabilities. Bowden's estimator can incorporate sightings of marked birds that are not uniquely identAuthorsD.R. DiefenbachMovement and habitat use of sika and white-tailed deer on Assateague Island National Seashore, Maryland
This research project was conducted to describe habitat use of sika deer (Cervus nippon) and white-tailed deer (Odocoileus virginianus) and possibly attribute the effects of ungulate herbivory to specific deer species, if spatial separation in habitat use could be identified. Sturm (2007) conducted an exclosure study to document the effect of feral horse (Equus caballus) herbivory, deer herbivory,AuthorsDuane R. Diefenbach, Sonja ChristensenModeling distribution of dispersal distances in male white-tailed deer
Dispersal distances and their distribution pattern are important to understanding such phenomena as disease spread and gene flow, but oftentimes dispersal characteristics are modeled as a fixed trait for a given species. We found that dispersal distributions differ for spring and autumn dispersals of yearling male white-tailed deer (Odocoileus virginianus) but that combined data can be adequatelyAuthorsD.R. Diefenbach, E.S. Long, C.S. Rosenberry, B.D. Wallingford, D. R. SmithMultiple proximate and ultimate causes of natal dispersal in white-tailed deer
Proximate and ultimate causes of dispersal in vertebrates vary, and relative importance of these causes is poorly understood. Among populations, inter- and intrasexual social cues for dispersal are thought to reduce inbreeding and local mate competition, respectively, and specific emigration cue may affect dispersal distance, such that inbreeding avoidance dispersal tends to be farther than disperAuthorsE.S. Long, D.R. Diefenbach, C.S. Rosenberry, B.D. WallingfordDeer hunting on Pennsylvania's public and private lands: A two-tiered system of hunters?
Recreational hunting is crucial for controlling white-tailed deer populations. Public land is increasingly important as access to private lands declines. However, differences between public and private land hunters remain unknown. Our study of Pennsylvania hunters revealed differences between private and public land hunters that may pose problems for management. Hunters who only hunted public landAuthorsR.C. Stedman, P. Bhandari, A.E. Luloff, D.R. Diefenbach, J.C. FinleyIncorporating availability for detection in estimates of bird abundance
Several bird-survey methods have been proposed that provide an estimated detection probability so that bird-count statistics can be used to estimate bird abundance. However, some of these estimators adjust counts of birds observed by the probability that a bird is detected and assume that all birds are available to be detected at the time of the survey. We marked male Henslow's Sparrows (AmmodramuAuthorsD.R. Diefenbach, M.R. Marshall, J.A. Mattice, D.W. BrauningSpatial organization of a reintroduced population of bobcats
The spacing patterns and mating systems of solitary carnivores have important implications for social behavior and for the survival and reproduction of individuals. Over 2 years, we reintroduced 32 (15 males and 17 females) bobcats (Lynx rufus) to a barrier island off the coast of Georgia and studied patterns of bobcat spatial distribution. Population density increased to 3.1 bobcats/10 km2. We foAuthorsD.R. Diefenbach, L.A. Hansen, R.J. Warren, M.J. ConroyControlling for anthropogenically induced atmospheric variation in stable carbon isotope studies
Increased use of stable isotope analysis to examine food-web dynamics, migration, transfer of nutrients, and behavior will likely result in expansion of stable isotope studies investigating human-induced global changes. Recent elevation of atmospheric CO2 concentration, related primarily to fossil fuel combustion, has reduced atmospheric CO2 ??13C (13C/12C), and this change in isotopic baseline haAuthorsE.S. Long, R.A. Sweitzer, D.R. Diefenbach, M. Ben-DavidForest cover influences dispersal distance of white-tailed deer
Animal dispersal patterns influence gene flow, disease spread, population dynamics, spread of invasive species, and establishment of rare or endangered species. Although differences in dispersal distances among taxa have been reported, few studies have described plasticity of dispersal distance among populations of a single species. In 2002-2003, we radiomarked 308 juvenile (7- to 10-month-old), mAuthorsE.S. Long, D.R. Diefenbach, C.S. Rosenberry, B.D. Wallingford, M.D. GrundAnnual survival estimation of migratory songbirds confounded by incomplete breeding site-fidelity: Study designs that may help
Many species of bird exhibit varying degrees of site-fidelity to the previous year's territory or breeding area, a phenomenon we refer to as incomplete breeding site-fidelity. If the territory they occupy is located beyond the bounds of the study area or search area (i.e., they have emigrated from the study area), the bird will go undetected and is therefore indistinguishable from dead individualsAuthorsM.R. Marshall, D.R. Diefenbach, L.A. Wood, R.J. Cooper - Science