Duane Diefenbach, PhD (Former Employee)

Natural and anthropogenic landscape features, such as rivers, mountain ranges, and roads can alter animal dispersal paths and movement patterns. Consequently landscape, through its effects on dispersal, may influence many ecological processes, including disease transmission, invasion dynamics, and gene flow. To investigate influences of landscape features on dispersal patterns of a large...

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...

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...

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...

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...

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...

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...

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...

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

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...

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...

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...