Eastern Spotted Skunk Research Articles

Increasing Detections of Small to Medium-Sized Mammals Using Multiple Game Cameras

Surveys using game cameras have become a standard method to determine presence of small to medium-sized mammals such as Spilogale putorius (Eastern Spotted Skunk). Surveys typically use a single camera at each site; however, prior work with other species suggests that single cameras are less likely than multiple cameras to detect small and mid-size mammals. During the winters of 2019–2020 and 2020–2021, we placed 71 camera stations in the Arkansas Ozarks, with each station having 2 cameras aimed at the same target. We used detections of a common species, Sciurus carolinensis (Eastern Gray Squirrel), to determine if adding an additional camera at each site could increase detections of animals similar in size. Overall, detections increased 27% with the addition of a second camera. We found that a second camera increased Eastern Gray Squirrel detections by 15.6% when the animal was closer than 1 body-length from the target bait tree and 41.2% when the animal was more than 1 body-length from the bait tree. We conclude that a single camera may miss a significant number of detections of small to medium-sized animals and could bias results of detection/non-detection studies.

A Review of Camera-Trapping Methodology for Eastern Spotted Skunks

Abstract Eastern spotted skunks Spilogale putorius are an understudied species that has experienced range-wide declines. Over the past 16 y, camera traps have become an increasingly common tool to monitor and understand their current distribution. To inform best surveying practices, we reviewed 16 camera-trap studies specifically targeting this species. We focused on reported latency to initial detection and three main aspects of study design: seasonality of detections, baits and lures, and camera-trap brands. Latency to initial detection ranged from 1 to 82 d with a mean of 17.1 d (SD = 9.1). Attractants varied among projects, but most (75%) used sardines as bait. The percentage of skunk detections tended to vary across the year, with the highest percentage of skunk detections occurring in March (92%). We conclude by suggesting best practices and directions for future research techniques that will aid in developing more efficient methods to address key knowledge gaps for this elusive species. Given the long timeframes for latency to initial detection, monitoring individual sites for at least 4 wk, with the use of bait, is likely the best strategy to detect eastern spotted skunks. We encourage further experimental approaches on the effectiveness of different baits and lures, and methods to increase latency to initial detection. Collectively, we hope this leads to the development of a standardized monitoring approach that researchers can implement across studies and states within the eastern spotted skunk's range.

Status and Distribution of the Eastern Spotted Skunk in Maryland: A Historic Review and Recent Assessment

There have been no confirmed detections of Spilogale putorius (Eastern Spotted Skunk) since 1967 in Maryland. We summarized historical records, as well as recent studies from other available mammal projects completed in Maryland. We conducted camera-trap surveys between 2015 and 2018 at 33 sites in western Maryland. We sought information from outdoor recreationists, mail-surveys sent to licensed wildlife damage control operators (n = 56), and an online questionnaire of natural resources professionals (n = 149). We compiled 13 historic records, including 7 catalogued specimens. No Eastern Spotted Skunks were detected with our camera traps. Our call for public information did not result in any confirmed sightings, and there were no personal observations or secondary evidence reported by responding wildlife damage control operators (n = 10) or natural resource professionals (n = 49). It appears the Eastern Spotted Skunk may no longer be a permanent resident in Maryland. However, the state still retains potential habitat and is in close proximity to known populations in West Virginia, from which Eastern Spotted Skunks could potentially disperse to Maryland in the future.

Predicted Spatial Distribution of the Eastern Spotted Skunk (Spilogale putorius) in Virginia Using Detection and Non-Detection Records

The geographic distribution of a species is a fundamental component in understanding its ecology and is necessary for forming effective conservation plans. For rare and elusive species of conservation concern, accurate maps of predicted occurrence are particularly problematic and often highly subjective. Spilogale putorius (Eastern Spotted Skunk) populations have experienced large declines since the 1940s. Their elusive behavior and perceived rarity result in low detection probability when using conventional methods for sampling small mammals. Low detection probability often causes uncertainty as to where Eastern Spotted Skunks could be a management concern. We modeled the distribution of predicted occurrence of Eastern Spotted Skunks using verifiable occurrence and non-detection records obtained throughout Virginia from 2010 to 2020. Occurrence data consisted of trapping records reported to the Virginia Department of Wildlife Resources, incidental photo-verified reports of sightings and road-killed animals, and remote-camera detections. Non-detections were presumed at baited remote-camera locations following intense survey efforts. We fit predicted occurrence models using generalized linear modeling in an information-theoretic framework using the package ‘stats’ in Program R. Our results incidated a greater probability of presence from the Blue Ridge westward, increasing with slope steepness along northeastern- to southeastern-facing slopes and decreasing with slope steepness along southeastern- to southwestern-facing slopes. Emergent rock outcrops prominent along northeastern slopes offer ample protective rocky cover, whereas mixed Quercus spp. (oak), Kalmia latifolia (Mountain Laurel), and Rhododendron maximum (Rosebay Rhododendron) forest communities along southern-facing slopes provide suitable areas of cover, both of which are critical for spotted skunk survival and reproductive success. Our analysis provides insight into the relationships between landscape features and Eastern Spotted Skunk distributions across Virginia. Understanding these relationships is critical for the effective management and conservation of this vulnerable species.

Detection of Eastern Spotted Skunks on Pine Mountain in Southeastern Kentucky Using Baited Enclosed Track Plates

Spilogale putorius (Eastern Spotted Skunk) is listed as a species of greatest conservation need by Kentucky Department of Fish and Wildlife Resources. The objective of this study was to use enclosed track plates to investigate whether the species occurred in 7 protected areas along Pine Mountain in eastern Kentucky. We inventoried 30 sites from December 2017 through March 2018. We detected skunks in March at 2 different sites located at Kingdom Come Preserve and Hensley Pine Wildlife Management Area. We recommend further inventories for Eastern Spotted Skunks on Pine Mountain and comparisons of enclosed track plates to remote camera traps to detect Eastern Spotted Skunks in Appalachia.

Burrow Excavation by an Eastern Spotted Skunk and Visitation by a Long-Tailed Weasel

In this field note, we detail video evidence of Spilogale putorius (Eastern Spotted Skunk) further excavating a den site that was subsequently visited by Mustela frenata (Long-tailed Weasel). In October 2019 in Burke County, NC, we tracked a radio-collared Eastern Spotted Skunk to a small ground burrow. A camera trap was set outside the den entrance for 7 days. During this period, we observed that the burrow was occupied by 1 or more individual spotted skunks, and concurrently occupied by 2 spotted skunks on at least 1 occasion. The burrow was further excavated by 1 of the spotted skunks, representing the first recorded footage of this behavior in the Eastern Spotted Skunk. On 1 occasion, between visits to the den by the spotted skunks, a Long-tailed Weasel investigated the burrow. This observation represents one of the first close associations between these cryptic species.

Optimization of Camera-Trap Surveys for Eastern Spotted Skunks and Other Meso-Mammals in the Appalachian Foothills

We conducted baited camera-trap surveys in eastern Kentucky during October 2017–April 2018 to assess the efficacy of survey duration and attractant type in detecting Spilogale putorius (Eastern Spotted Skunk) and other Appalachian meso-mammals. We surveyed 16 sites across 10 counties over more than 1200 trap-nights. We observed meso-mammals of 9 species, including 3 records of Eastern Spotted Skunks. Our results indicated that a 2-week survey duration with sardine bait yielded meso-mammal detection rates, richness estimates, and species accumulation curves comparable to a 4-week survey duration with sardine bait; the addition of fatty acid scent tablets did not affect results. However, Eastern Spotted Skunks were not recorded until an average of 15 days after deployment, suggesting that species-specific trapping rates must be considered in the duration of camera-trap surveys.

Canine Distemper Outbreak in a Population of Eastern Spotted Skunks

Canine distemper is an epizootic disease that can cause high mortality rates in carnivores, such as mustelids, and can have important deleterious effects on vulnerable, often small, carnivore populations due to its highly transmissible nature. In April and May 2020, we recovered 5 Spilogale putorius (Eastern Spotted Skunk) carcasses over a 15-day period that showed no visible signs of trauma. Clinical examination of the carcasses indicated that the skunks died due to canine distemper. Four of these skunks were radio-collared as part of our research at the time of their deaths, meaning that 50% of our study sample succumbed to distemper. Additionally, 2 other skunks we had radio-collared went missing during this time and might have contracted and died of distemper as well. To our knowledge, this is the first documented outbreak of distemper in Eastern Spotted Skunks. Our observation underscores the need to further study the effects of disease on the declining Eastern Spotted Skunk across its range.

Distribution and Relative Abundance of Eastern Spotted Skunk Records across Their Range

Evidence suggests the range of Spilogale putorius (Eastern Spotted Skunk) has contracted and its abundance has declined in the past 70 years, leading to conservation concerns. We summarized county records of Eastern Spotted Skunks collected during 2000–2020 to determine the current range and relative abundance of the species. We accumulated 1174 records from 257 counties across its historic range in the United States, with 901 records from 197 counties considered verified. Verified records included museum specimens, photo-documented occurrences, and captures by researchers. We created 2 distribution maps: one of their current range based on all occurrence records and another from only verified records. Records indicated the Eastern Spotted Skunk persisted across a large portion of its historic range, and is relatively abundant in the Interior Highlands, Appalachian Mountains, central Texas, central South Dakota, and south Florida. Our results also suggest that the species' overall range has contracted since 1959. Regions with a relatively high abundance of current records covered a variety of ecosystems, including agricultural areas, grasslands, woodlands, and forests. These data provide managers with information concerning where research and conservation efforts can be focused for this potentially declining species.

Demography of the Appalachian Spotted Skunk (Spilogale putorius putorius)

Spilogale putorius (Eastern Spotted Skunk) is a small, secretive carnivore that has substantially declined throughout the eastern United States since the mid-1900s. To better understand the current status of Eastern Spotted Skunks, we studied survival and reproduction of the S. p. putorius (Appalachian Spotted Skunk) subspecies across 4 states in the central and southern Appalachian Mountains from 2014 to 2020. Using encounter histories from 99 radio-collared Appalachian Spotted Skunks in a Kaplan–Meier known-fate survival analysis, we calculated a mean annual adult survival rate of 0.58. We did not find support for this survival rate varying by sex, predator cover (canopy cover and topographic ruggedness), or climate. Compared to estimates of survival from previous research, our data suggest that Appalachian Spotted Skunk survival is intermediate to the S. p. interrupta (Plains Spotted Skunk) and S. p. ambarvalis (Florida Spotted Skunk) subspecies of Eastern Spotted Skunk. We located 11 Appalachian Spotted Skunk natal dens and estimated mean litter size to be 2.8 juveniles per female. We used a Lefkovitch matrix to identify the most important demographic rates and found that adult survivorship had the largest impact on the population growth rate. These results provide important demographic information for future Eastern Spotted Skunk population viability analyses and can serve as a baseline for future comparative assessments of the effects of management interventions on the species.

Temporal Assessment of Eastern Spotted Skunk Geographic Distribution

Spilogale putorius (Eastern Spotted Skunk) experienced range-wide population declines beginning in the mid-1900s with no clear understanding of the causal mechanism or whether such declines were associated with range contractions. Species-distribution models can provide a powerful framework to assess changes in landscape suitability in response to changing environmental conditions. Herein, we modeled time-stepped distributions of suitable environmental conditions for Eastern Spotted Skunks from 1938 to 2016 in Maxent, incorporating climate and land-cover predictors. Climate and land-cover variables reliably predicted landscape suitability of Eastern Spotted Skunks over time. We found a 37% decline in suitable area from historic predictions, consistent with reports of population declines in these areas. Our predicted landscape-suitability maps can be used to evaluate the current distribution of environmentally suitable conditions for the species as well as guide research and conservation efforts.

Den-Site Selection by Eastern Spotted Skunks in the Central Appalachian Mountains of West Virginia

We assessed den-site selection of Spilogale putorius (Eastern Spotted Skunk) in the Appalachian Mountains of West Virginia by radio-tracking 8 individuals to 83 dens from January 2018 to October 2019. We measured local habitat characteristics at den sites and nearby, presumed unused paired sites and compared the habitat predictors via binary logistic regression. Results from the averaged model indicated greater understory cover from stems of Kalmia latifolia (Mountain Laurel) and Vaccinium spp. (Blueberry) and Gaylussacia spp. (Huckleberry), as well as medium to large rocks, and coarse woody debris increased the odds of a den site being used. Medium to large rocks were the most influential predictor of a den site. Our results suggest Eastern Spotted Skunks in this region would likely benefit from management practices that increase density of understory cover and coarse woody debris and preserve rocky outcroppings.

River Crossings by Two Male Eastern Spotted Skunks in West Virginia

Spilogale putorius (Eastern Spotted Skunk) populations have declined throughout their range and may now be extirpated from the northeast in Pennsylvania and Maryland. Populations have persisted south of the Potomac River along shared mountain ranges in Virginia and West Virginia. Little is known about the dispersal capabilities of the species, including if large riverine systems inhibit their dispersal. During a radio-telemetry study of 8 Eastern Spotted Skunks in West Virginia, 2 males crossed the South Branch of the Potomac River (SBPR) on 9 occasions. Crossings may have been motivated by breeding movements, as 7 occurred during the breeding season. Stretches of the Potomac River similar in size to the SBPR might not inhibit the natural recolonization of the northeastern range.

Itching for Recognition: Dermatophytosis Identified in an Eastern Spotted Skunk (Spilogale putorius) Population in Texas

The diversity, clinical manifestations, and impact on overall health of pathogenic fungi in Spilogale putorius (Eastern Spotted Skunk [ESS]) have been poorly investigated. Herein, we describe the first reported cases of fungal dermatitis in ESS from a population in southeastern Texas. In 2016, two of 3 ESS live-trapped in Harris County, TX, exhibited symptoms consistent with dermatophytosis. We isolated fungus from 1 of 2 cultures grown from scraped samples of infected ESS skin and morphologically identified it as Microsporum canis. Reviewing local wildlife rehabilitation records, we were able to confirm the prevalence of dermatophytosis within local mephitid populations. We examine the implications of the discovery of a zoonotic fungal pathogen in ESS in light of its importance in wildlife medicine as well as its ramifications for the health of domestic animals and humans.

Advancing Small Carnivore Research and Conservation: The Eastern Spotted Skunk Cooperative Study Group Model

Nearly half of all small carnivore species are declining globally, with many in danger of extinction and requiring urgent conservation attention. We herein describe the formation of a conservation group focused on the formerly poorly understood Spilogale putorius (Eastern Spotted Skunk). The Eastern Spotted Skunk Cooperative Study Group (CSG) was formed in 2015 by experts in the biology and management of the species and currently contains 143 members representing 29 state agencies, 24 universities, 6 federal agencies, 3 non-governmental organizations, and 2 tribal nations. The goals of the CSG are to (1) enhance communication about the species, (2) identify management and research priorities, and (3) facilitate collaborative planning, funding, outreach, monitoring, and research opportunities. This voluntary group has made progress on all 3 goals by facilitating collaborative research and outreach that have greatly advanced our understanding and awareness of the species, including the drafting of a species conservation plan that has been endorsed by every regional government committee that oversees management of Eastern Spotted Skunks across their range. We conclude by profiling the lessons learned and future directions for the CSG, with the hopes that the CSG could be a model for advancing conservation of small carnivores and other species in need of attention around the globe.

First Documentation of Two Types of Aboveground Den Structures in the Eastern Spotted Skunk (Spilogale putorius)

Spilogale putorius (Eastern Spotted Skunk) is a small, nocturnal carnivore that typically spends daylight hours resting in underground den sites. During a study on the den-site selection of S. p. ambarvalis (Florida Spotted Skunk) in the dry prairie of south-central Florida in 2016 and 2017, we tracked individuals to discernible aboveground structures composed of vegetation on 25 occasions. These structures were 1 of 2 easily distinguishable types: large mounds of vegetation primarily composed of shredded Serenoa repens (Saw Palmetto), or smaller cup-like structures with a horizontal entrance that resembled a ground-nesting bird's nest. These sites were occasionally reused by individual skunks, and on 1 occasion we observed 2 female spotted skunks occupying a site at the same time. Due to the absence of other wildlife species in the study area capable of making such structures, we believe that these structures were created by the skunks themselves. While Eastern Spotted Skunks are known to pull vegetation into their underground burrows, and have been documented occupying man-made structures (e.g., haystacks) as den sites, our observations represent the first documentation of aboveground, self-constructed structures being repeatedly used by this species. Use of these structures might be unique to Florida Spotted Skunk due to reduced predation risk or occasional flooding in the region that temporarily reduces availability of underground den sites.

Infectious Diseases of Eastern Spotted Skunks (Spilogale putorius) within a One Health Framework

Owing to their omnivorous diet, den-site habits, foraging activities, mating behaviors, and other pertinent habitat-use and natural-history traits, Spilogale putorius (Eastern Spotted Skunk [ESS]) are exposed to a wide variety of pathogenic agents. Understanding the diversity of infectious diseases affecting ESS in conjunction with the role this species plays in the disease ecology of these pathogens is crucial not only for devising efficacious management strategies, but also in formulating comprehensive veterinary and public health strategies for combatting zoonotic diseases associated with this species. Herein I review the reported infectious diseases of ESS. I address the implications of these pathogens for current and future population health of the species with reference to the changing dynamics of ESS disease ecology, influenced by increasing habitat fragmentation, exposure to pathogens across the domestic–wildlife interface, fluctuating climatic patterns, antimicrobial-resistant pathogens, and the profusion of immunosuppressant chemicals throughout the environment. Employing a One Health framework to evaluate the role that ESS play in the disease ecology of zoonoses further highlights the interrelationships of ESS health to the health of humans, domestic animals, and other wildlife. The potential for ESS to serve as hosts, “dilutors”, and/or sentinels for zoonoses underscores their importance in public health and provides an opportunity to leverage their potential disease-mitigating attributes for the conservation of ESS aligned with their provision of ecosystem services.

Effects of Seasonality and Bait Type on Capture Efficacy and Sex Ratio of Plains Spotted Skunks

Improper or inefficient survey designs are commonly cited as underlying issues contributing to failure to detect rare or understudied species. Researchers primarily rely on information obtained when species were widely distributed and abundant to inform research design. Recently, interest in Spilogale putorius (Eastern Spotted Skunk) has piqued due to declining populations and an uncertain conservation status. To address knowledge gaps on the effects of seasonality, bait choice, and survey design on capture efficacy and sex ratio, we surveyed Spilogale putorius interrupta (Plains Spotted Skunk) in the Katy Prairie region of Texas with 2 survey designs. Our systematic survey design provided 2 bait types, a 5-day survey length, and a grid array of traps, while our casual live-trapping surveys had 1 bait type with varied survey length and trap array. From February 2019 through August 2020, we captured 29 unique Plains Spotted Skunks 49 times. Analysis of systematic survey data indicates that seasonality and bait type did not affect capture success. Additionally, surveys conducted in the summer resulted in similar overall capture rates but higher female capture rates when compared to other seasons. Our finding of similar capture rates among seasons is in contrast to previous reports that suggest reduced capture efficacy of spotted skunks during the summer. These results improve the current knowledge of techniques for capturing spotted skunks and offer more efficient means for researchers to assess populations.

Camera-Trapping Survey for Plains Spotted Skunk (Spilogale putorius interrupta) in Eastern Oklahoma

Once known as a regularly harvested fur bearer, Spilogale putorius (Eastern Spotted Skunk) has experienced drastic population decline and is now considered a species of conservation concern throughout much of its range. In an effort to contribute to distribution and habitat presence data in Oklahoma, we surveyed 95 locations using camera traps during the months of October and April (2018–2019 and 2019–2020) attempting to detect the S. p. interrupta (Plains Spotted Skunk) subspecies. We began surveying the Ouachita National Forest in eastern Oklahoma and broadened our survey to include areas of recently confirmed sightings. We only detected Eastern Spotted Skunks in 5 of the 95 locations that were surveyed, during 12 of the 5287 trap nights, and 13 of the 2085 mammal detections. Although we had low trap success, we believe our results are useful in supporting the rarity of, or difficulty detecting, this species. Additionally, the information resulting from this study should be useful in establishing a basis for continued sampling in Oklahoma and providing information to improve sampling technique and design when researching this species.

Mating behavior of Eastern Spotted Skunk Spilogale putorius Linnaeus, 1758 (Mammalia: Carnivora: Mephitidae) revealed by camera trap in Texas, USA

Eastern Spotted Skunks Spilogale putorius are an understudied Vulnerable small carnivore. Here we report a novel capture of Eastern Spotted Skunks mating via a camera trap in central Texas. This detection adds to the minimal natural history knowledge of the species and highlights the utility of camera traps for documenting rarely observed behaviors.