James C. Beasley

A Hierarchical Analysis of Habitat Selection by Raccoons in Northern Indiana

Abstract Although numerous studies have examined habitat use by raccoons (Procyon lotor), information regarding seasonal habitat selection related to resource availability in agricultural landscapes is lacking for this species. Additionally, few studies using radiotelemetry have investigated habitat selection at multiple spatial scales or core-use areas by raccoons. We examined seasonal habitat selection of 55 (31 M, 24 F) adult raccoons at 3 hierarchical orders defined by the movement behavior of this species (second-order home range, second-order core-use area, and third-order home range) in northern Indiana, USA, from May 2003 to June 2005. Using compositional analysis, we assessed whether habitat selection differed from random and ranked habitat types in order of selection during the crop growing period (season 1) and corn maturation period (season 2), which represented substantial shifts in resource availability to raccoons. Habitat rankings differed across hierarchical orders, between seasons within hierarchical orders, and between sexes within seasons; however, seasonal and intersexual patterns of habitat selection were not consistent across hierarchical orders of spatial scale. When nonrandom utilization was detected, both sexes consistently selected forest cover over other available habitats. Seasonal differences in habitat selection were most evident at the core-area scale, where raccoon selection of agricultural lands was highest during the maturation season when corn was available as a direct food source. Habitat use did not differ from availability for either sex in either season at the third-order scale. The selection of forest cover across both seasons and all spatial orders suggested that raccoon distribution and abundance in fragmented landscapes is likely dependent on the availability and distribution of forest cover, or habitats associated with forest (i.e., water), within the landscape. The lack of consistency in habitat selection across hierarchical scales further exemplifies the need to examine multiple biological scales in habitat-selection studies.

Home-Range Attributes of Raccoons in a Fragmented Agricultural Region of Northern Indiana

Abstract For many wildlife species, agricultural landscapes undergo spatial and temporal fluctuations in the composition of food and cover annually with the planting and harvesting of crops. Raccoon (Procyon lotor) populations have flourished in agricultural landscapes, where crops increase foraging opportunities and efficiencies. However, information is lacking regarding the effects of temporal shifts in food and cover resulting from agricultural activities on raccoon home ranges. We examined home-range characteristics of 60 (33 M, 27 F) adult raccoons in northern Indiana, USA, from May 2003 through June 2005 to identify shifts in the size of home ranges and core use areas among seasons defined by crop availability and crop developmental stages. Mean fixed-kernel home-range (92 ± 6 ha; 𝑥̄ ± SE) and core-area sizes (20 ± 2 ha) of males were significantly larger than those of females (58 ± 7 ha and 13 ± 2 ha, respectively), and both were smaller than those reported for raccoons in other fragmented agricultural landscapes. Home-range sizes varied little among seasons for either sex. However, home ranges of males were smallest during the crop maturation stage, whereas home ranges of females were smallest during the crop growing season. The results of our study suggest that even in expansive rural landscapes, raccoons can maintain small home ranges when food, water, and denning resources are readily available. Additionally, the lack of differences among seasonal home-range sizes, despite the presence of an ephemeral superabundant food source (i.e., corn) during the maturation season, was likely due to the close proximity of foraging and denning resources across seasons.

Reducing Baylisascaris procyonis Roundworm Larvae in Raccoon Latrines

Baylisascaris procyonis roundworms, a parasite of raccoons, can infect humans, sometimes fatally. Parasite eggs can remain viable in raccoon latrines for years. To develop a management technique for parasite eggs, we tested anthelmintic baiting. The prevalence of eggs decreased at latrines, and larval infections decreased among intermediate hosts, indicating that baiting is effective.

Spatio-temporal variation in the demographic attributes of a generalist mesopredator

Human land-use practices have dramatically altered the composition and configuration of native habitats throughout many ecosystems. Within heterogeneous landscapes generalist predators often thrive, causing cascading effects on local biological communities, yet there are few data to suggest how attributes of fragmentation influence local population dynamics of these species. We monitored 25 raccoon (Procyon lotor) populations from 2004 to 2009 in a fragmented agricultural landscape to evaluate the influence of local and landscape habitat attributes on spatial and temporal variation in demography. Our results indicate that agricultural ecosystems support increased densities of raccoons relative to many other rural landscapes, but that spatial and temporal variation in demography exists that is driven by non-agricultural habitat attributes rather than the availability of crops. At the landscape scale, both density and population stability were positively associated with the size and contiguity of forest patches, while at the local scale density was positively correlated with plant diversity and the density of tree cavities. In addition, populations occupying forest patches with greater levels of plant diversity and stable water resources exhibited less temporal variability than populations with limited plant species complexity or water availability. The proportion of populations comprised of females was most strongly influenced by the availability of tree cavities and soft mast. Despite the abundance of mesopredators in heterogeneous landscapes, our results indicate that all patches do not contribute equally to the regional abundance and persistence of these species. Thus, a clear understanding of how landscape attributes contribute to variation in demography is critical to the optimization of management strategies.

Long-term census data reveal abundant wildlife populations at Chernobyl

Summary Following the 1986 Chernobyl accident, 116,000 people were permanently evacuated from the 4,200 km 2 Chernobyl exclusion zone [1]. There is continuing scientific and public debate surrounding the fate of wildlife that remained in the abandoned area. Several previous studies of the Chernobyl exclusion zone (e.g. [2,3]) indicated major radiation effects and pronounced reductions in wildlife populations at dose rates well below those thought [4,5] to cause significant impacts. In contrast, our long-term empirical data showed no evidence of a negative influence of radiation on mammal abundance. Relative abundances of elk, roe deer, red deer and wild boar within the Chernobyl exclusion zone are similar to those in four (uncontaminated) nature reserves in the region and wolf abundance is more than 7 times higher. Additionally, our earlier helicopter survey data show rising trends in elk, roe deer and wild boar abundances from one to ten years post-accident. These results demonstrate for the first time that, regardless of potential radiation effects on individual animals, the Chernobyl exclusion zone supports an abundant mammal community after nearly three decades of chronic radiation exposures.

Addressing ecological effects of radiation on populations and ecosystems to improve protection of the environment against radiation: Agreed statements from a Consensus Symposium.

This paper reports the output of a consensus symposium organized by the International Union of Radioecology in November 2015. The symposium gathered an academically diverse group of 30 scientists to consider the still debated ecological impact of radiation on populations and ecosystems. Stimulated by the Chernobyl and Fukushima disasters’ accidental contamination of the environment, there is increasing interest in developing environmental radiation protection frameworks. Scientific research conducted in a variety of laboratory and field settings has improved our knowledge of the effects of ionizing radiation on the environment. However, the results from such studies sometimes appear contradictory and there is disagreement about the implications for risk assessment. The Symposium discussions therefore focused on issues that might lead to different interpretations of the results, such as laboratory versus field approaches, organism versus population and ecosystemic inference strategies, dose estimation approaches and their significance under chronic exposure conditions. The participating scientists, from across the spectrum of disciplines and research areas, extending also beyond the traditional radioecology community, successfully developed a constructive spirit directed at understanding discrepancies. From the discussions, the group has derived seven consensus statements related to environmental protection against radiation, which are supplemented with some recommendations. Each of these statements is contextualized and discussed in view of contributing to the orientation and integration of future research, the results of which should yield better consensus on the ecological impact of radiation and consolidate suitable approaches for efficient radiological protection of the environment.

Use of Rhodamine B to Reveal Patterns of Interspecific Competition and Bait Acceptance in Raccoons

Abstract Passive treatment of raccoons (Procyon lotor) through distribution of vaccine-laden baits recently has emerged as a potential solution to address health and economic conflicts associated with raccoon rabies and may have applications in the management of other pathogens carried by raccoons if frequent bait deployments are used. Consumption of baits by nontarget species reduces the efficiency in which baits can be used to manage wildlife disease, although no study has explicitly evaluated the influence of bait competitor density on the ability to treat raccoons. Our objectives were to use the biomarker Rhodamine B (RB) to 1) evaluate patterns of raccoon bait acceptance as a function of competition with Virginia opossums (Didelphis virginiana), the dominant bait competitor; 2) characterize attributes of opossum bait acceptance to improve efficiency of raccoon treatment; and 3) evaluate the effect of repeated bait exposure on rates of bait acceptance as may be required in the management of wildlife disease issues beyond rabies. Identifying bait consumption by individuals based on the presence of an RB mark in a sample of whiskers, we used logistic regression to model raccoon and opossum bait acceptance as a function of bait availability, previous exposure to baits, demographic attributes, and an index of time spent in the baited area (residency index). For both raccoons and opossums, the best measure of bait availability was the variable number of baits per opossum. The most parsimonious logistic regression model for raccoon bait acceptance included the variables baits per opossum, exposure history, and residency index. The strength of the variable baits per opossum relative to competing measures of bait availability indicated bait consumption by opossums significantly limited the ability to treat raccoons. The most parsimonious model for opossum acceptance was composed of the variables baits per opossum, sex, weight, residency index, baits per opossum × sex, and weight × sex. Patterns of opossum bait acceptance likely were driven by effects of bait availability and sex-dependent differences in movement. Our results call attention to the importance of bait competition in limiting the ability to effectively treat raccoon populations through distribution of baits and suggest managers incorporate information on density of bait competitors, particularly opossums, in allocation of baits.

A Genetic Analysis of the Virginia Opossum Mating System: Evidence of Multiple Paternity in a Highly Fragmented Landscape

Using molecular techniques, we examined patterns of paternity in Virginia opossums occupying a highly fragmented agricultural landscape in northern Indiana. During 2008, we collected tissue from 64 females and their pouch young in 34 forest patches distributed over a 1100-km(2) region. Using genotypes from 10 microsatellite loci, we determined the minimum number of fathers contributing to each litter using GERUD 1.0. Genotyped offspring with known mothers were then analyzed using CERVUS 3.0, incorporating genotypes from 317 males sampled from 2007-2008 to identify potential fathers. Our analyses revealed that promiscuity was common among females, with 26 (41%) litters having > or = 2 sires. Despite the fact that we intensively sampled forest patches for potential fathers, we only were able to identify 13 fathers contributing to 14 litters, with an average Euclidean distance of 18.7 km between father-offspring pairs found in disparate patches (N = 6). Our inability to identify most (85%) fathers of sampled litters, coupled with the extensive distances observed between putative father-offspring pairs, suggests that opossums may not maintain explicit home ranges in highly fragmented landscapes.

Effects of Culling on Mesopredator Population Dynamics

Anthropogenic changes in land use and the extirpation of apex predators have facilitated explosive growth of mesopredator populations. Consequently, many species have been subjected to extensive control throughout portions of their range due to their integral role as generalist predators and reservoirs of zoonotic disease. Yet, few studies have monitored the effects of landscape composition or configuration on the demographic or behavioral response of mesopredators to population manipulation. During 2007 we removed 382 raccoons (Procyon lotor) from 30 forest patches throughout a fragmented agricultural ecosystem to test hypotheses regarding the effects of habitat isolation on population recovery and role of range expansion and dispersal in patch colonization of mesopredators in heterogeneous landscapes. Patches were allowed to recolonize naturally and demographic restructuring of patches was monitored from 2008–2010 using mark-recapture. An additional 25 control patches were monitored as a baseline measure of demography. After 3 years only 40% of experimental patches had returned to pre-removal densities. This stagnant recovery was driven by low colonization rates of females, resulting in little to no within-patch recruitment. Colonizing raccoons were predominantly young males, suggesting that dispersal, rather than range expansion, was the primary mechanism driving population recovery. Contrary to our prediction, neither landscape connectivity nor measured local habitat attributes influenced colonization rates, likely due to the high dispersal capability of raccoons and limited role of range expansion in patch colonization. Although culling is commonly used to control local populations of many mesopredators, we demonstrate that such practices create severe disruptions in population demography that may be counterproductive to disease management in fragmented landscapes due to an influx of dispersing males into depopulated areas. However, given the slow repopulation rates observed in our study, localized depopulation may be effective at reducing negative ecological impacts of mesopredators in fragmented landscapes at limited spatial and temporal scales.

Habitats associated with vehicle collisions with wild pigs

Abstract Context. Over the past few decades, the frequency of wild pig–vehicle collisions (WPVCs) and number of human fatalities associated with these accidents have increased with expanding populations of this species, particularly in regions outside its native distribution. Aims. To better understand this widespread and growing human safety threat, we quantified habitat attributes associated with 311 WPVC locations occurring between 1983 and 2012 at the Savannah River Site (SRS) in South Carolina, USA, to test the hypothesis that WPVCs occur more frequently in areas proximal to preferred habitats (i.e. riparian and bottomland hardwood habitats). Methods. At each collision site, we measured the distance to the nearest wetland and stream, as well as the composition of habitats within 100-m and 1699-m buffers. We then contrasted habitat attributes associated with collision sites with those from randomly selected locations along the same roads, to identify habitat characteristics contributing to a higher incidence of these accidents. Key results. WPVCs were non-randomly distributed across both spatial scales measured, with collisions occurring more frequently in areas of preferred habitat for this species. Specifically, collisions occurred in areas closer to streams and containing less pine forest than at random locations at both spatial scales evaluated. Conclusions. Similar to vehicle accidents with other ungulate species, our study suggested that vehicle collisions involving wild pigs are spatially clustered around preferred habitat types. Management efforts to reduce vehicle collisions with wild pigs should be focussed in areas where roadways bisect preferred habitats such as stream crossings and bottomland hardwood or other riparian habitats. Implications. These data will aid in the development of mitigation strategies to reduce the frequency and impacts of WPVCs in areas of high wild-pig densities. However, given the paucity of data on WPVC mitigation, additional research is needed to quantify the efficacy of various methods (e.g. signage, fencing, underpasses) at reducing the frequency and severity of collisions with this species.