Mephitis Mephitis Research Articles

The effects of red fox scent on winter activity patterns of suburban wildlife: evaluating predator-prey interactions and the importance of groundhog burrows in promoting biodiversity

During winter, prey species in suburban areas of the northeastern United States must consider trade-offs in maximizing survival while they are simultaneously constrained by predators and climatic conditions associated with winter such as snow and low temperatures. Many mammalian prey mitigate the physiological stress from the cold by taking refuge in burrows. Some have also developed olfactory sensitivity to predator scent cues as they attempt to avoid predation in the landscape of fear and co-evolutionary arms race between predators and prey. The Eastern cottontail (Sylvilagus floridanus) is one of these species that both uses burrows in winter and is sensitive to scents. However, despite the importance of cottontails in the diet of Red foxes (Vulpes vulpes), one of their major predators, little is known about scent cues that cottontails use to detect foxes. Eastern cottontails and other suburban wildlife that occupied burrows dug by Groundhogs near Ithaca, New York, USA were exposed to scent wicks treated with Red fox urine during the winter of 2017–2018 to determine if the frequency of burrow use would decrease because of a perceived heightened risk of predation. We observed no response to the predator odor by cottontails and the other burrow-utilizing species. This lack of a behavioral response by prey may be due to the attenuation of fear in suburban environments. A surprising variety of mammalian and avian taxa (n = 22) were recorded at burrows, including Striped skunks, mice, Domestic cats, Virginia opossums, Bobcats, White-tailed deer, Weasels, a Coyote, and a Gray fox. Surprisingly we did not observe a single Red fox, for whom intraspecific scent cues are also important. We also documented daily patterns of activity around burrows of the five most commonly observed taxa. Our investigation reveals that Groundhogs are notable ecosystem engineers whose burrows function as important landscape features and local hotspots of biodiversity during the winter in a suburban ecosystem.

American Dog Ticks (Dermacentor variabilis) as Biological Indicators of an Association between the Enteric Bacterium Moellerella wisconsensis and Striped Skunks (Mephitis mephitis) in Southwestern Manitoba, Canada.

Total genomic (g)DNA from 100 American dog ticks (Dermacentor variabilis) collected from humans, dogs, raccoons, and skunks near Minnedosa (Manitoba, Canada) in 2005 was tested for the presence of Moellerella wisconsensis (Gammaproteobacteria: Enterobacteriales) using PCR. Although two gDNA samples derived from ticks attached to two striped skunks (Mephitis mephitis) contained M. wisconsensis DNA, it is unlikely that D. variabilis is a vector of this bacterium. Genomic DNA prepared from the washes of the external surfaces of these two ticks (i.e., before DNA extraction from the whole tick) and another two ticks attached to same skunks were also PCR positive for M. wisconsensis. This suggests that ticks acquired the bacterium by physical contact with contaminated or infected skunks. However, it does not exclude the possibility that the ticks may have also imbibed the bacterium from their host blood and lymph. Nonetheless, the results of this molecular study suggest that the four adult D. variabilis represent biological indicators of the presence of M. wisconsensis in association with their vertebrate hosts (i.e., striped skunks). Additional work is needed to determine if M. wisconsensis is present in the blood and lymph of striped skunks in southwestern Manitoba and if there are potential health risks for persons coming into contact with infected animals.

Reserves as double-edged sword: Avoidance behavior in an urban-adjacent wildland

Human activities affect wildlife in a variety of direct (e.g., hunting, supplemental feeding, and culling) and indirect (e.g., displacement from habitat loss, competition with introduced invasive species, and avoidance of human-dominated landscapes) ways. Even ostensibly benign activities such as hiking or horseback riding in established parks may affect the spatial and temporal activity patterns of wildlife species. Characterization and quantification of effects is essential if parks and other protected areas are to balance the dual needs to nurture an appreciation of wildlands or satisfy a need to encounter nature (sensu the biophilia hypotheses) and to ensure that wild animals can survive and reproduce. We explored how human presence affects wildlife presence in a spatially extensive system of camera traps established in various protected areas in coastal southern California. To characterize and quantify effects we developed a conceptual framework on the basis of joint probabilities of occurrence on a per-camera basis and created a novel statistical approach to assess whether observed probabilities of co-occurrence differed from expected probabilities of co-occurrence. We found that same-day co-occurrence of wildlife and humans was significantly lower than expected at >90% of the cameras established. This pattern held across sites, across the seven species of large and medium-sized mammals (Bobcat Lynx rufus, Mountain Lion Puma concolor, Gray Fox Urocyon cinereoargenteus, Coyote Canis latrans, Striped Skunk Mephitis mephitis, Northern Raccoon Procyon lotor, and Mule Deer Odocoileis hemionus), and across the five types of human disturbance examined (hikers, bicyclists, domestic dogs, vehicles, and equestrians). Our results demonstrate that human presence acutely affects same-day wildlife detections in protected areas, supporting the hypothesis that avoidance behaviour is a type of “mortality-free predation.” Adaptive and flexible management plans need to be established, evaluated, and updated regularly to facilitate the human nature experience while lessening as much as possible long-term degradation of wildlife habitat. Wildlife in urban-adjacent preserves constitute a major part of the nature experience by humans and require effective management of pressures for use and recreation along aside those for wildlife habitat needs.

Partial molecular characterization of the mitochondrial genome of Baylisascaris columnaris and prevalence of infection in a wild population of Striped skunks.

Members of the genus Baylisascaris utilize omnivores or carnivores as their definitive hosts. The best known member of this genus is Baylisascaris procyonis, which is an intestinal parasite of raccoons. The closest relative of B. procyonis is B. columnaris, which utilizes the common skunk as its definitive host. Although B. procyonis has been extensively studied, relatively little is known of B. columnaris. For example, the mitochondrial genome of B. procyonis has been sequenced in its entirety. Conversely, the mitochondrial genome of B. columnaris remains largely unexplored. Likewise, the prevalence of this parasite in its wild host has not been documented. In this study, we collected parasites from a wild population of skunks in the state of Utah, United States. The cytochrome c oxidase subunit 1 and 2 genes, NADH dehydrogenase 2 and several tRNA genes were sequenced from the mitochondrial genome of these parasites. We also determined the prevalence of B. columnaris in a wild population of skunks. In this work we identify several novel polymorphic genetic loci between B. procyonis and B. columnaris. These findings provide additional molecular targets for the differentiation of Baylisascaris species through clarification of genetic differences between B. columnaris and B. procyonis.

Graphically Characterizing the Movement of a Rabid Striped Skunk Epizootic Across the Landscape in Northwestern Wyoming

A striped skunk (Mephitis mephitis) rabies epizootic in northwestern Wyoming was studied from the Index Case in 1988 to the last case in 1993, and possibly is the first rabies epizootic in a previously rabies-free zone monitored from beginning to end. The 843 km(2) study area comprised skunk habitat along 90 km of Shoshone River's floodplain from Bighorn Lake upstream to Cody. Of 1,015 skunks tested, 215 were rabies-positive. Integrating spatial and temporal data from positive cases, we analyzed the epizootic's movements and dynamics at 6-month intervals using multivariate movement maps, a new multivariate descriptive methodology presented here to demonstrate the epizootic's directional flow, while illustrating areas with higher case densities (i.e., wave crests). This approach should help epidemiologists and public health officials to better understand future rabies epizootics.

Influence of Wind and Humidity on Foraging Behavior of Olfactory Mesopredators

Many mammalian predators rely on scents to locate prey and weather conditions that affect an odor plume (i.e., scents suspended in air) or depositional odor (i.e., scents laid on the ground) should affect predator foraging behavior. We predicted that wind speed, wind direction, and humidity would influence the foraging behavior of olfactory mesopredators. We tested these predictions by conducting spotlight surveys for foraging Red Foxes (Vulpes vulpes), Striped Skunks (Mephitis mephitis), and Raccoons (Procyon lotor) along the dike surrounding Willard Bay Reservoir in Willard, Utah, from August 2008 to August 2009. We recorded predator species, locations, numbers, and weather conditions at the time each predator was observed. While humidity had no effect on foraging, wind speed and direction were significant predictors of a predator's nightly foraging activity, with most predators observed when wind speeds were 2 to 4 m/s and winds were blowing perpendicularly over the dike the dike rather than parallel to the dike. Wind speed and direction also influenced where predators foraged on the dike, with predators being more likely to forage on the windward side of the dike when wind speeds were high enough to cause turbulence. We detected differences among predator species in their response to wind speed: Raccoons were more active than Striped Skunks and Red Foxes when the wind was calm and blowing parallel to the dike. Overall, our results indicate that these predator species alter their foraging behavior based on wind speed and wind direction. By foraging when winds were light and blowing perpendicularly over the dike, predators could likely enhance their ability to locate food using olfaction.

A Group Defense Incident Involving Juvenile Striped Skunks, <em>Mephitis mephitis</em>

Striped Skunks (Mephitis mephitis) occasionally fall prey to various predators. To reduce the risk of predation, Striped Skunks have evolved multiple defensive behaviors and aposematic coloration. Several types of defensive behaviors have been reported for individual Striped Skunks, but never for a group of skunks. We describe a group defense incident in an encounter between four juvenile Striped Skunks and a perceived predator—a man on a motorcycle.

Influence of Gender and Den Type on Home Range Shape for Striped Skunks, <em>Mephitis mephitis</em>, in Saskatchewan

We investigated gender differences in shape of home ranges for Striped Skunks, Mephitis mephitis, in southcentral Saskatchewan, Canada, during 1993-1994. Data collected on free-ranging Striped Skunks indicated that shape of female home ranges was unaffected by den type (building versus burrow) and was similar to shape of male home ranges. Moreover, type of maternity den did not influence the position of the den within the home range (inside or outside of core area). We conclude that the distribution of Striped Skunks in summer, and the distribution of their foraging activity, are not affected by the availability of anthropogenic den structures.

Rabies Challenge of Captive Striped Skunks (Mephitis mephitis) following Oral Administration of a Live Vaccinia-Vectored Rabies Vaccine

Twenty-four adult striped skunks (Mephitis mephitis) were administered the raccoon product formulation of Rabies Vaccine, Live Vaccinia-Vectored (Raboral V-RG, Merial Limited, Athens, Georgia, USA), either by oral instillation or in vaccine-filled coated sachets either as single or multiple doses. A control group remained unvaccinated. Twenty-three of the skunks were challenged 116 days postvaccination with rabies virus (skunk isolate). Six of six naive skunks succumbed to challenge. Four of six skunks that received the vaccine by oral instillation survived challenge. The skunks that did not survive failed to seroconvert following vaccination. None of the skunks that accepted multiple doses of the vaccine offered in coated sachets survived challenge, nor were rabies virus-neutralizing antibodies (VNAs) detected in the sera. Likewise, none of the five skunks ingesting a single sachet developed VNA against rabies. However, in this group one skunk did survive rabies challenge. This preliminary study showed that the vaccinia-vectored oral rabies vaccine Raboral V-RG, as formulated for use in raccoons, is capable of protecting a percentage of skunks against rabies. However, although the fishmeal-coated sachets were readily consumed, subsequent challenge of these animals revealed poor vaccine delivery efficiency.

Extrinsic Effects on Long-term Population Trends of Virginia Opossums and Striped Skunks at a Large Spatial Scale

Abstract Long-term data on wildlife populations are needed to elucidate the relative importance of extrinsic factors on population dynamics; however, such data are rare for most species such as medium-sized mammals. We present long-term population indices for Virginia opossums (Didelphis virginiana) and striped skunks (Mephitis mephitis) in Illinois from 1975 to 1998. Annual road-kill indices (RKI) and spotlight indices were correlated for opossums, but not for skunks. Opossum indices exhibited an overall increase (P < 0.01) during the study, but there was no trend since 1983. Skunk RKI exhibited a negative slope (P < 0.01), but this was influenced by a fluctuation in RKI during the late 1970s and there has been no overall trend since. Mean winter temperatures (t − 1) were positively correlated with opossum RKI, but were not correlated with skunk RKI. Estimated harvest (t = 0) was positively related to skunk RKI, and effective harvest was positively correlated with opossum RKI. Annual rabies cases in skun...

The radiating mousing technique of the striped skunk

The radiating mousing technique of the striped skunk

Spatial Organization of a Prairie Striped Skunk Population during the Waterfowl Nesting Season

Information on the spatial organization of the striped skunk (Mephitis mephitis) is required for the management of this species as a predator of waterfowl eggs. Radiocollared striped skunks were tracked in southcentral Saskatchewan from April through August, 1993 (6 M, 13 F) and 1994 (2 M, 15 F). Home ranges (100% minimum convex polygon) of males (11.6 ± 2.8 km 2 , n = 5) were larger (P < 0.01) than those of females (3.7 ± 0.3 km 2 , n = 21). Similarly, core areas of males (3.0 ± 1.2 km 2 ) were larger (P < 0.01) than those of females (1.0 ± 0.1 km 2 ). Extensive intrasexual overlap occurred among home ranges (71 ± 4%) and core areas (26 ± 7%) of females. Daily ranges of striped skunks did not vary with sex or biological season (preparturition, parturition-rearing, predispersal, dispersal), and averaged 1.39 ± 0.26 km 2 for males and 1.11 ± 0.17 km 2 for females. Neither males nor females scent-marked, and all individuals were solitary (except females with young). Females are likely more important predators of duck eggs than males because females are more abundant, have overlapping ranges, and travel their home ranges more intensively.

The influence of close-range radio-tracking on the behavior of free-ranging Striped Skunks, Mephitis mephitis

The influence of close-range radio-tracking on the behavior of free-ranging Striped Skunks, Mephitis mephitis

Physical Characteristics of Striped Skunks in Northern Minnesota

Etude des differences de poids, de mensurations corporelle et crânienne, de pelage en fonction de: sexe, âge, saison pour des Mephitis mephitis du nord-est du Comte d'Itasca

Evaluation of Mark-Recapture for Estimating Striped Skunk Abundance

The mark-recapture method for estimating striped skunk (Mephitis mephitis) abundance was evaluated by systematically livetrapping a radio-equipped population on a 31.4-km2 study area in North Dakota during late April of 1977 and 1978. The study population was 10 females and 13 males in 1977 and 20 females and 8 males in 1978. Skunks were almost exclusively nocturnal. Males traveled greater nightly distances than females (3.3 vs. 2.6 km, P < 0.05) and had larger home ranges (308 vs. 242 ha) although not significantly so. Increased windchill reduced night-time activity. The population was demographically but not geographically closed. Frequency of capture was positively correlated with time skunks spent on the study area. Little variation in capture probabilities was found among trap-nights. Skunks exhibited neither trap-proneness nor shyness. Capture rates in 1977 were higher for males than for females; the reverse occurred in 1978. Variation in individual capture rates was indicated among males in 1977 and among females in 1978. Ten estimators produced generally similar results, but all underestimated true population size. Underestimation was a function of the number of untrapped skunks, primarily those that spent limited time on the study area. The jackknife method produced the best estimates of skunk abundance. J. WILDL MANAGE. 49(2):332-340 The estimation of animal abundance is often difficult. Mark-recapture is used commonly to estimate the abundance of secretive mammals, including striped skunks (Verts 1967, Bailey 1971, Lynch 1972). Although there are many estimators available (Cormack 1968, 1979; Otis et al. 1978; Pollock 1981; Seber 1982), there are few data on their application to populations of known size. This paper assesses the applicability of several estimators with data for populations of striped skunks of known size in 2 years and discusses aspects of skunk biology that influence capture probability. Although captures in this study are fewer than desired for most markrecapture evaluations, the approach represents a practical application of the mark-recapture method. W. B. Bicknell and J. L. Piehl provided field assistance. Radiotelemetry equipment was obtained from the James Ford Bell Mus., Cedar Creek Natl. Hist. Area, Univ. of Minnesota, St. Paul. D. R. Anderson and G. C. White provided the CAPTURE computer program. Appreciation is extended to D. W. Sparling, who verified J. Wildl. Manage. 49(2):1985 STRIPED SKUNK MARK-RECAPTURE * Greenwood et al. 333 some of the calculations and reviewed the manuscript, and to D. R. Anderson, K. P. Burnham, R. M. Cormack, L. L. Eberhardt, D. L. Otis, K. H. Pollock, and G. C. White, who provided constructive comments on the manu-

Hindlimb joint angle changes and action of the primary ankle extensor muscles during posture and locomotion in the Striped skunk (Mephitis mephitis)

Knee (femorotibial), ankle (talocrural) and metatarsophalangeal joint angles during posture and locomotion were determined for the adult Striped skunk, Mephitis mephitis. Cinematography of animals moving overground and cineradiography of animals walking on a treadmill are the basis for joint angle measurements. These data allowed for the documentation of muscle length change of the primary ankle extensors, soleus, medial and lateral gastrocnemius and plantaris during stepping. Whole muscle length—active tension curves were determined on anaesthetized skunks. Appropriate moment arms were measured over the physiological range of knee and ankle angles. This study provides some mechanical and musculoskeletal data of the ankle of M. mephitis and provides for comparison and contrast to similar data for the domestic cat. Major findings include: (1) the length—active tetanic tension curves of the ankle extensors tend to be broad over a wider range of lengths in M. mephitis than in the cat, (2) the range of lengths at which the ankle extensors are actively used is relatively narrow in both species, (3) as both animals walk faster the working range of the muscles is closer to the maximum in situ length, (4) a broader range of ankle joint angles exists for M. rnephitis than for the cat at which the length—active tension curve and moment arm curve interact to provide maximum or near maximum torque, and (5) in general, the stance phase of the skunk is initiated at muscle lengths (relative to standing length) that are much shorter than those of the cat which may result in greater elastic storage for the cat durine E2.These data coupled with an analysis of gait selection of M. mephitis lead us to conclude that many features of the posture, locomotion and musculoskeletal design of the ankle extensor system of this species are primitive. The cat deviates from the primitive condition to some extent related to its more extreme specialization toward a jumping and sprinting way of life. Nevertheless, the domestic cat is a useful musculoskeletal model for studies concerned with the neural control of mammalian locomotion.

Reproduction in Captive Striped Skunks (Mephitis mephitis)

Reproduction in Captive Striped Skunks (Mephitis mephitis)

Food Intake, Weight Changes and Activity of Confined Striped Skunks (Mephitis mephitis) in Winter

Four striped skunks (Mephitis mephitis) were held outdoors near Winnipeg, Manitoba, Canada, throughout the winter with an unlimited food supply to< examine aspects of winter dormancy in this species. Body weights and food intake were measured at monthly and weekly intervals, respectively. A treadle positioned at the entrance to each nest box and wired to an Esterline-Angus event recorder provided a continuous quantitative record of physical activity. No evidence of natural hypothermia was observed. Body weights increased in October and November, remained stable in December and January, decreased in February and March, and increased in April. Physical activity followed the same fundamental pattern shown by food intake. Both food intake and physical activity showed a strong correlation with ambient temperature. The skunks were largely nocturnal in October, November and April, but were strictly nocturnal from December to March inclusive. We consider the depression in growth, food intake and physical activity observed in the confined striped skunks in midwinter to be some of the characteristics of winter dormancy (carnivorean lethargy) in this species. We hypothesize that the characteristics of winter dormancy would be more fully expressed in the absence of a winter food supply.

Biology of Striped Skunks on a Southwestern Lake Erie Marsh

Striped skunks were studied on and near a 2083-acre marsh in northwestern Ohio in 1967 and 1968. The breeding season ranged from 12 February to 25 March, and the young were born from mid-April to mid-May. Most young skunks became self-sufficient in midAugust. The adult sex ratio averaged 0.8 male per female. Seventy-one per cent of the skunks examined were under 1 year old. Daily activity usually began within 60 min after sunset. Adult males and pregnant females were difficult to capture in the late spring and summer. Decreasing barometric pressure was significantly related to skunk captures. The average straight line distance between capture locations was 0.5 mile for adult males and females and 0.2 and 0.4 miles for juvenile males and females, respectively. Home ranges varied from 31 to 114 acres. The density of skunks in late summer was 12 per square mile. Skunks temporarily used the numerous dens on the dikes. Most of the 93 blue-winged teal and mallard nests observed were destroyed by predators, but skunks destroyed only 13 %. Waterfowl nesting areas surrounded by deep channels or over 0.5 mile from areas frequented by skunks were relatively safe from skunk predation.

An Improved Technique for Handling Striped Skunks in Disease Investigations

An Improved Technique for Handling Striped Skunks in Disease Investigations