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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

Filter Total Items: 67

Caution is warranted when using animal space-use and movement to infer behavioral states

BackgroundIdentifying the behavioral state for wild animals that can’t be directly observed is of growing interest to the ecological community. Advances in telemetry technology and statistical methodologies allow researchers to use space-use and movement metrics to infer the underlying, latent, behavioral state of an animal without direct observations. For example, researchers studying ungulate ec
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Cooperative Research Units

The future of managing ungulate species: White-tailed eeer as a case study

The future challenge to managing ungulate populations to meet objectives is likely to become more difficult as participation in recreational hunting declines and ungulate populations become more abundant. The authors use the white-tailed deer (Odocoileus virginianus) in North America as a case study to illustrate the management challenges facing decision makers. In states with fewer licensed deer
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Cooperative Research Units

Demography and loss of genetic diversity in two insular populations of the bobcat (Lynx rufus)

Among felids worldwide, only 6 of 38 species have stable or increasing populations, and most felid species are threatened by anthropogenic influences, especially habitat loss and fragmentation. We documented changes in genetic diversity in an isolated, reintroduced population of bobcats on Cumberland Island (CUIS), Georgia, USA, compared to another bobcat population on Kiawah Island, South Carolin
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Cooperative Research Units

Risky movements? Natal dispersal does not decrease survival of a large herbivore

Natal dispersal is assumed to be a particularly risky movement behavior as individuals transfer, often long distances, from birth site to site of potential first reproduction. Though, because this behavior persists in populations, it is assumed that dispersal increases the fitness of individuals despite the potential for increased risk of mortality. The extent of dispersal risk, however, has rarel
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Cooperative Research Units

Modeling how to achieve localized areas of reduced white-tailed deer density

Localized management of white-tailed deer (Odocoileus virginianus) involves the removal of matriarchal family units with the intent to create areas of reduced deer density. However, application of this approach has not always been successful, possibly because of female dispersal and high deer densities. We developed a spatially explicit, agent-based model to investigate the intensity of deer remov
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Cooperative Research Units

Relative reproductive phenology and synchrony affect neonate survival in a nonprecocial ungulate

Degree of reproductive synchronization in prey is hypothesized as a predator defense strategy reducing prey risk via predator satiation or predator avoidance. Species with precocial young, especially those exposed to specialist predators, should be highly synchronous to satiate predators (predator satiation hypothesis), while prey with nonprecocial (i.e. altricial) young, especially those exposed
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Cooperative Research Units

Survival is negatively associated with glucocorticoids in a wild ungulate neonate

It is unknown how ungulate physiological responses to environmental perturbation influence overall population demographics. Moreover, neonatal physiological responses remain poorly studied despite the importance of neonatal survival to population growth. Glucocorticoid (GC) hormones potentially facilitate critical physiological and behavioral responses to environmental perturbations. However, elev
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Cooperative Research Units

Assessment of spatial genetic structure to identify populations at risk for infection of an emerging epizootic disease

Understanding the geographic extent and connectivity of wildlife populations can provide important insights into the management of disease outbreaks but defining patterns of population structure is difficult for widely distributed species. Landscape genetic analyses are powerful methods for identifying cryptic structure and movement patterns that may be associated with spatial epizootic patterns i
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Cooperative Research Units

Latitudinal variation in snowshoe hare (Lepus americanus) body mass: A test of Bergmann’s Rule

The relationship between body size and latitude have been the focus of dozens of studies across many species. However, results of testing Bergmann’s Rule – that organisms in colder climates or at higher latitudes possess larger body sizes – have been inconsistent across studies. We investigated whether snowshoe hares (Lepus americanus) follow the Rule by investigating differences in body mass usin
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Cooperative Research Units

Soil chemistry, and not short-term (1–2 year) deer exclusion, explains understory plant occupancy in forests affected by acid deposition

The loss of species diversity and plant community structure throughout the temperate deciduous forests of North America have often been attributed to overbrowsing by white-tailed deer (Odocoileus virginanus). Slow species recovery following removal from browsing, or reduction in deer density, has been termed a legacy effect of past deer herbivory. However, vegetation legacy effects have also coinc
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Cooperative Research Units

Effect of male age structure on reproduction in white-tailed deer

Selective harvest regimes that create female-biased sex ratios can potentially lead to delayed breeding, reduced breeding synchrony, reduced productivity, and a female-biased sex ratio of offspring. These resulting changes in breeding behavior and population dynamics have potential to adversely affect population growth. In 2002, Pennsylvania implemented harvest regulation changes that reduced deer
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Cooperative Research Units

Deer harvest variation in small and large management units in Pennsylvania

Large game management units often lead to criticisms from hunters because they assume smaller units possess less variation in wildlife populations and more closely represent their local area. In 2003, Pennsylvania, USA, replaced smaller, socio-political county-based management units with larger wildlife management units (WMUs). We tested the hypothesis that smaller county units possessed less vari
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Cooperative Research Units
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Bobcat

Unique Study of Isolated Bobcat Population Confirms Accuracy of Extinction Model

The reintroduction of 32 bobcats to an island off the coast of Georgia more than three decades ago created an ideal experiment to examine the accuracy of a genetic-modeling technique that predicts extinction of isolated wildlife populations. That’s the conclusion of Penn State researchers who continue to monitor the bobcat population on Cumberland Island National Seashore, and who conducted a...
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Ecosystems Mission Area, Cooperative Research Units
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Unique Study of Isolated Bobcat Population Confirms Accuracy of Extinction Model

The reintroduction of 32 bobcats to an island off the coast of Georgia more than three decades ago created an ideal experiment to examine the accuracy of a genetic-modeling technique that predicts extinction of isolated wildlife populations. That’s the conclusion of Penn State researchers who continue to monitor the bobcat population on Cumberland Island National Seashore, and who conducted a...
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