Den Site Selection by the Florida Spotted Skunk

The eastern spotted skunk (Spilogale putorius) is a species of conservation concern in much of its range and has experienced a decline since the early to mid-1990s. But the subspecies that inhabits peninsular Florida, the Florida spotted skunk (S. p. ambarvalis), might still be abundant and is an important nest predator of the endangered Florida grasshopper sparrow (Ammodramus savannarum floridanus). To gain insight on this little-studied subspecies and inform potential management strategies, we conducted a resource selection study on the Florida spotted skunk. We examined 5 hypotheses for den site selection related to den type, vegetation, and landscape characteristics in a dry prairie ecosystem in central Florida. We tracked 36 individual skunks to 757 den sites. Using discrete choice analysis, we found that male and nonbreeding female skunks at our study site were 5 times more likely to select a mammal burrow over a gopher tortoise (Gopherus polyphemus) burrow, that selection of a den site increased 34% for each 1-burrow increase in the number of nearby burrows, and that selection of a den site increased 3% for every 10-cm increase in a visual obstruction index. Similarly, breeding female skunks were more likely to select mammal burrows and shallow depressions over gopher tortoise burrows by 16-fold and 13-fold, respectively, and selection of a den site increased by 75% for every 1-burrow increase in the number of nearby burrows. In contrast to previous studies that occurred in forested, mountainous environments elsewhere in the species' range, our findings suggest that den characteristics might be more important than landscape or vegetation characteristics to Florida spotted skunk den site selection in dry prairie. Additionally, the frequency of prescribed fires on the landscape did not appear to affect Florida spotted skunk den site selection. Thus, Florida spotted skunks in this ecosystem might be landscape generalists, thereby potentially limiting the ability of managers to control nest predation by this subspecies through habitat management. © 2019 The Wildlife Society.     

Landscape Ecology of Eastern Spotted Skunks in Habitats Restored for Red‐Cockaded Woodpeckers

Although examples are rare, conflicts between species of conservation concern can result from habitat restoration that modifies habitat to benefit a single taxon. A forest restoration program designed to enhance habitat for endangered red‐cockaded woodpeckers (Picoides borealis) may be reducing available habitat for the eastern spotted skunk (Spilogale putorius), a forest‐adapted sympatric species of conservation concern that occurs in the Ouachita National Forest, Arkansas, U.S.A. At small scales, eastern spotted skunks select early successional forest with structural diversity, whereas red‐cockaded woodpeckers prefer mature pine (Pinus spp.) habitat. We surveyed for eastern spotted skunks at 50 managed forest stands, modeled occupancy as a function of landscape‐level habitat factors to examine how features of restoration practices influenced occurrence, and compared known occupied forest stands to those where active red‐cockaded woodpecker nesting clusters were located. The most‐supported occupancy models contained forest stand age (negatively associated) and size (positively associated); suggesting eastern spotted skunks primarily occupy large patches of habitat with dense understory and overhead cover. Red‐cockaded woodpecker nesting clusters were located in smaller and older forest stands. These results suggest that increased overhead cover, which can reduce risk of avian predation, enhances occupancy by small forest carnivores such as eastern spotted skunks. Management activities that increase forest stand rotation length reduce the availability of young dense forest. The practice may enhance the value of habitat for red‐cockaded woodpeckers, but may reduce the occurrence of eastern spotted skunks. Implementing plans that consider critical habitat and extinction risks for multiple species may reduce such conservation conflict.     

Rabies in skunks from Mexico.

An enzootic focus of rabies in skunks in Mexico is described. Fifty three wild animals including two badgers (Taxidea taxus), 32 bats (various species), one bobcat (Lynx rufus), two coatis (Nasua narica) three foxes (Urocyon cineroargenteus), one raccoon (Procyon lotor) and 12 skunks (see below) were tested for rabies by direct immunofluorescence assay from 1991 to 1997 in the central part of San Luis Potosi State, Mexico. Rabies occurrence was 21% of all tested mammals, with 19% in skunks and only 2% in other wild species (one bobcat). Skunks represented 23% of all mammals tested and had a rabies prevalence of 83%. Only 10 individuals were identified: three hog-nosed skunks (Conepatus leuconotus) and seven spotted skunks (Spilogale putorius). All were involved in human attacks; the spotted skunk attacks were inside bedrooms while people were sleeping, and the hog-nosed skunk attacks occurred outdoors. Skunk cases of rabies represented 40% of all rabies cases in 1997, and 100% of cases registered for wild animals in San Luis Potosi state. This situation constitutes an important public health problem and requires further epidemiological research to make the human population aware of the problem and to establish measures to limit further human attacks by rabid skunks.     

A new species of helietta (Rutaceae) from Guerrero and Jalisco,Mexico; A synopsis of the North American species

Helietta lottiae, a new species from tropical deciduous forest from Guerrero and Jalisco, Mexico, is described. A key to the North American species of the genus and their geographical distribution are presented.     

Evaluating detection and occupancy probabilities of eastern spotted skunks

The eastern spotted skunk (Spilogale putorius) is a poorly understood mesocarnivore species that suffered a range-wide decline in the mid-1900s. Little is known about its current distribution or habitat needs, and in the southern Appalachians, where the Carolinas and Georgia converge, eastern spotted skunks were only recently discovered to persist. From January–April in 2016 and 2017, we used camera trap surveys to monitor eastern spotted skunks and used occupancy modeling to evaluate factors we hypothesized would influence the probability of spotted skunk detection and occurrence at the landscape scale. We detected spotted skunks at 55.6% of our sites and on 18.5% of sampling occasions. Our results suggest that detection probability was influenced by predation risk, camera setup, and the type of scent-based attractant used. Eastern spotted skunk occupancy probability had a negative relationship with elevation, such that the probability of occupancy on average increased 7% for every 100-m decrease in elevation. These results differ from previous findings from the northern Appalachian region, and suggest spotted skunks in the southern Appalachians may be more widely distributed than previously thought. To inform management, there remains a critical need for finer-scale investigations into resource selection and demographic trends. © 2019 The Wildlife Society.     

Predicted distribution of plains spotted skunk in Arkansas and Missouri

The plains spotted skunk (Spilogale interrupta) is of conservation concern because of widespread population declines and is being considered for listing under the United States Endangered Species Act. Although the taxon is relatively rare and difficult to study, recent research and reports provided some information about spotted skunks in Arkansas and Missouri, USA. Using this information, we employed full and simplified multivariate species distribution models to evaluate cover type associations and identify regions of high predicted presence for plains spotted skunks. The simple model contained percent forest and percent development within 5 km, land cover category, and distance to water. Percent forest within 5 km was the most important variable based on permutation importance in both models, indicating that plains spotted skunk habitat may persist in contiguous forest at the landscape scale. Regions predicted to have high presence occurred in northern, western, and southern Arkansas and southern Missouri, totaling >300,000 ha. The resulting plains spotted skunk distribution map can be used for research and management efforts in areas of high probability of occurrence, and future statewide survey efforts may validate our results.     

Identification of skunk species submitted for rabies testing in the desert southwest

Skunks usually are identified by their common name (skunk) when submitted for rabies testing. In the desert southwest (Arizona, New Mexico, Texas, USA; and northern Mexico), there are five species of skunks; four of which can occur in sympatry. To better understand the ecology of skunk rabies in these areas, it is imperative that species be properly identified. We used the displacement loop (d-loop) of the mitochondrial genome to identify to species 24 skunk brain samples submitted for rabies testing in New Mexico from 2001 to 2002. Most were identified as striped skunks (Mephitis mephitis), but hooded (Mephitis macroura) and hog-nosed (Conepatus leuconotus) skunks were also found.     

Nesting Habitat of the Lilac-crowned Parrot in a Modified Landscape in Mexico

Parrot populations are being increasingly pressured to occupy modified or fragmented landscapes, yet little is known of the habitat requirements of most species, particularly with regard to the effects on breeding habitat. We evaluated nesting habitat of the lilac-crowned parrot Amazona finschi in the modified landscape of coastal Michoacan in Mexico. We located 90 parrot nests in 12 tree species in Michoacan, with lilac-crowned parrots presenting a narrow niche-breadth of tree species used for nesting. Considering an additional 82 nest trees recorded for lilac-crowned parrots in Jalisco, we determined a 51 percent similarity in cavity resource use by parrots in the two dry forest regions. Overall, the predominant nest tree species with 76 percent of nests were Astronium graveolens , Piranhea mexicana , Brosimum alicastrum , and Tabebuia spp., all characteristic of semi-deciduous forest. Only 8 percent of nests occurred in trees characteristic of deciduous forest. Parrots utilized large trees with canopy level cavities as nest sites, and preferred conserved semi-deciduous forest for nesting, with fewer nests than expected in deciduous forest and transformed agricultural land. Nest areas in semi-deciduous forest occurred on significantly steeper terrain, as remnant semi-deciduous forest is restricted to steep ridges and canyons. Those parrot nests in modified habitats and forest patches were located near to continuous forest, with nest trees in open agricultural land being significantly closer to continuous forest than nests in disturbed forest patches. These results demonstrate the importance of conserved semi-deciduous forest as breeding habitat for the threatened, endemic lilac-crowned parrot, making wild populations of the species vulnerable to the high rate of transformation and fragmentation of tropical dry forest.     

Necrophilous coleoptera (Scarabaeidae, Silphidae y Trogidae) of Malinalco, State of Mexico, Mexico

Collections were made during one year, between August 2005 and July 2006, in Malinalco, State of Mexico, in three sites of tropical deciduous forest, a pasture and a induced forest of pine-oak, established in a altitudinal gradient ranging from 1,253 m to 2,300 m. The total of 7,680 specimens Scarabaeidae, Silphidae and Trogidae were captured through NTP-80, representing 18 genera and 38 species. Onthophagus and Canthon contained 46% of the richness of Scarabaeidae. The more distant sites were complementary in their species composition. The lowest complementarity occurred between sites with tropical deciduous forest. It revises the material collected through pitffal traps and light traps funnel type, increasing the list of 38 to 50 species in the study area. Between 40% and 50% of the species in Malinalco are distributed in localities of the province of the basin Balsas and localities of the province of the Sierra Madre del Sur, and 30% in the localities of the province of Pacifica coast. For the first time 17 species of Scarabaeidae and three Trogidae were reported for the State of Mexico.     

Effects of fire and agricultural practices on neotropical ant communities

Fire is extensively used in agricultural management in Mexico. There is little information on the effects of those practices on the abundance and diversity of animals that live within these forest soils. We studied the effect of slashing, burning and land use in a tropical deciduous forest on ant communities in the State of Jalisco, Mexico. The original vegetation (tropical deciduous forest) was modified into a corn field. Sampling was carried out in five stages: before slashing, after slashing, after burning, after seeding and after harvest. We found that very severe fires greatly reduced ant diversity. The most important effect of fire was the reduction of ant density, and the change of species composition and trophic guilds. These changes are relevant in the recycling process of energy in the ecosystem.     

A survey of parasites identified in the feces of eastern spotted skunks (Spilogale putorius) in western Arkansas

The endoparasite community of the eastern spotted skunk (Spilogale putorius) is poorly known. We surveyed parasites found in the feces of 29 eastern spotted skunks captured between March 2005 and January 2007 from a population in west-central Arkansas as part of a broader study of the ecology of the species. We identified 13 species (nine nematodes, four protozoa) from 82 fecal samples. Mean (+/-SD) number of species per individual skunk was 4.1+/-2.1, although this is likely an underestimate because some individuals were sampled more intensively than others. Most of the identified parasite species were also found in other skunk species or in other small carnivore species.     

Denning ecology of Molina's hog-nosed skunk in a farmland area in the Pampas grassland of Argentina

This paper reports the very first data on the denning habits of the little-studied Molina’s hog-nosed skunk (Conepatus chinga). We identified and characterized 240 (males: n = 92, females: n = 148) den sites used by nine radio-tracked skunks from November 2002 to October 2003 and from December 2005 to October 2007. Most dens were found in underground burrows and we found no variation in dimensions of den entrances across seasons. On average, 24.1% of the den sites were reused by C. chinga. Den sites were not homogeneously distributed within an animal's home range, being the density in core areas greater than in proximity to the borders of home ranges. C. chinga selected specific habitat characteristics for their den sites, such as high shrub and grass cover. Accordingly, the habitats preferred by skunks were native grasslands and pastures. Also, C. chinga preferred den sites located close to fences, roads, and grass patches. We argue that these preferences for den sites may provide two, not mutually exclusive, advantages: access to consistent and predictable sources of food, and protection from predators. Our results suggest that availability of semi-natural grassland and pasture areas may favor the conservation of C. chinga in the human-modified landscapes of the Pampas.     

Commonness,rarity, and oligarchies of woody plants in the tropical dry forests of Mexico

We assessed woody plant communities in two widely separated forests in the tropical dry forest (TDF) biome of Mexico for evidence of similar patterns of species commonness and rarity. We used belt transects laid out along contour lines (i.e., constant elevation) and stratified across elevation gradients at sites in Jalisco and Oaxaca to sample woody plant species diversity, abundance, relative frequency and basal area. We assembled a combined species list and compared species found in both sites (shared) to species found in only one site, assessing whether the most and least common species at a site tended to be shared or unshared. Of the 8242 individuals sampled, 370 species or morpho‐species were identified, with 222 species recorded at the Jalisco site and 270 at the Oaxaca site—122 (33%) species were shared across sites. Abundance, frequency and basal area of shared species were greater on average than for unshared species, and were positively correlated across sites. A subset of 68 shared species (18%) accounted for over half of all individuals encountered at the two sites. Species in the most common quartile were more likely to be shared than expected by chance, while species in the least common quartile were less likely. A genus‐level analysis found similar patterns. Our findings suggest that the TDF of Pacific coast Mexico shows evidence of widespread dominance by a small subset of species. These findings have potentially important implications for predicting species composition, understanding the role of oligarchic species in ecological processes, and conserving rare species.     

Habitat Use of Western Spotted Skunks and Striped Skunks in Texas

ABSTRACT Little information on foraging habitats of sympatric species of skunks in Texas, USA, is available. We compared 11 western spotted skunks (Spilogale gracilis) and 10 striped skunks (Mephitis mephitis) using radiotelemetry data to assess habitat use during foraging at broad levels of selection in a fragmented habitat. Western spotted skunks used areas with more large mesquite (Prosopis glandulosa) trees than did striped skunks and randomly selected points. Striped skunk habitat use was not different from randomly chosen locations. Contrary to previous research, both species appear to avoid agricultural habitat. A habitat management plan may be difficult to implement for striped skunks in Texas because they did not favor any available habitat. Conservation of western spotted skunks in west-central Texas should focus on areas with older mesquite trees, areas that are now often brush controlled for management of livestock.     

Denning ecology of the striped skunk in the Canadian prairies: implications for waterfowl nest predation

1. From 1993 to 1995, we studied the summer denning ecology of 40 radio-collared striped skunks Mephitis mephitis (32 females, eight males) during the waterfowl nesting season in Saskatchewan, Canada.
2. Forty-seven natal dens were used by 30 females. Natal den sites were either underground burrows (55%) or holes underneath buildings (45%), and were preferably located in farmsteads.
3. Male and female striped skunks used similar resting sites which consisted of above-ground retreats (57%), underground burrows (23%), buildings (17%) and culverts (3%).
4. Habitat preferences for resting sites did not differ between males and females: both sexes preferred farmsteads and wetlands, whereas managed waterfowl nesting areas, woodland and miscellanous habitats were avoided. Cropland was avoided for both natal dens and resting sites.
5. Females did not simultaneously share natal dens or resting sites, but both types of retreats were occupied by different females over time. Natal dens were occupied for 47 ± 3 days for females using a single den vs. 60 ± 3 days for females using >1 natal dens. Den switching may have been induced by a build-up of faeces.
6. Management of natal den sites such as abandoned farmsteads and buildings may provide an avenue of non-destructive predator management that is less expensive and controversial than exclusion or control.     

Hematology and serum chemistry of the island spotted skunk on Santa Cruz Island

We determined serum biochemistry and hematologic values for island spotted skunks (Spilogale gracilis amphiala) on Santa Cruz Island (California, USA). Samples were collected from island spotted skunks chemically restrained with ketamine hydrochloride and acepromazine in August 1999 (dry season) and from skunks manually restrained in August 2000 (dry season) and January 2001 (wet season). One parameter, glucose, significantly differed with season, with higher levels during the wet season. Serum chemistry and hematologic profiles suggest that method of restraint (manual or chemical), as well as other methodologic details, may influence blood characteristics in the island spotted skunk.     

Microbial macroecology: highly structured prokaryotic soil assemblages in a tropical deciduous forest

Aim To assess the hypothesis that free‐living prokaryotes show a pattern of ‘no biogeography’ by examining the scaling of soil prokaryotic diversity and by comparing it with other groups’ biogeographical patterns. Location Two sites in the tropical deciduous forest of Chamela, Jalisco, on the western coast of Mexico. Methods We examined the diversity and distribution of soil prokaryotes in two 8 × 8 m quadrats divided in such manner that we could sample at four spatial scales. Restriction fragment length polymorphisms of 16S rRNA genes were used to define operational taxonomic units (OTUs) that we used in lieu of species to assess diversity. Results We found highly structured species assemblages that allowed us to reject multiple predictions of the hypothesis that soil bacteria show ‘no biogeography’. The frequency distribution of range size (measured as the occupancy of quadrats) of OTUs followed a hollow curve similar to that of vertebrates on continents. Assemblages showed high levels of beta diversity and a non‐random nested pattern of diversity. OTU diversity scaled with area followed a power function with slopes z = 0.42 and 0.47. Main conclusions We demonstrate a non‐ubiquitous dispersal for soil prokaryotes, which suggests a complex biogeography similar to that found for terrestrial vertebrates.     

Dung beetle assemblages in primary forest and disturbed habitats in a tropical dry forest landscape in western Mexico

Dung beetles (Scarabaeinae) are conspicuous components in most terrestrial ecosystems, performing important ecological functions and services. Being sensitive to several types of disturbance, they have been successfully used as indicators of habitat change. Dung beetle communities in tropical rainforests have been well studied, but considerably less information is available for tropical dry forests. In this study I sampled dung beetles in two undisturbed habitats, deciduous forest and semideciduous forest, and two disturbed habitats, secondary forest and open area habitat, in the Chamela-Cuixmala region of western Mexico. Dung beetle species with high indicator value for each habitat were identified. Beetle abundance, observed species richness and estimated species richness were similar in the three forest habitats, but significantly lower in the open area habitat. A more detailed analysis of species-specific abundances in the three forest habitats revealed some differences. Transects of one of the undisturbed habitats, the deciduous forest, were more similar to the non-adjacent transects of disturbed secondary forest, than to the adjacent undisturbed semideciduous forest transects. Unlike studies in other tropical sites that have found a decrease in equitability in Scarabaeinae assemblages between undisturbed forest and disturbed habitat (particularly open habitats), in the Chamela-Cuixmala region all four habitats showed similar low equitability in community structure, with two or three very dominant species.     

Resource utilization by two insular endemic mammalian carnivores,the island fox and island spotted skunk

We compared resource utilization of two insular endemic mammalian carnivores, the island spotted skunk and island fox, along niche dimensions of space, food, and time on Santa Cruz Island. We predicted that resource use by foxes and skunks would differ along one or more niche dimensions, and that both species would have broader niches or higher densities compared with mainland relatives. Island foxes and island spotted skunks differed to some extent in habitat use, diets, and circadian activity, which may account for their long-term coexistence. Nonetheless, substantial overlap between skunks and foxes in spatial, dietary, and temporal dimensions suggests that competition between the two species does occur. Moreover, competition may be asymmetric, affecting skunks more than foxes. Compared with mainland foxes, island foxes have smaller body size, smaller home range, increased population density, increased diurnal activity, and behavior that is more highly inquisitive and less flightprone all common features of insular faunas. Island skunks, however, apparently have not developed these changes, perhaps due to asymmetric competition with foxes in conjunction with severe ecosystem disturbances caused by feral sheep.     

Leaf phenology is associated with soil water availability and xylem traits in a tropical dry forest

In tropical dry forests, spatial heterogeneity in soil water availability is thought to determine interspecific differences in key components of resource use strategies, such as leaf phenology and xylem function. To understand the environmental drivers of variation in leaf phenology and xylem function, we explored the relation of soil water potential to topographic metrics derived from a digital elevation model. Subsequently, we compared nine xylem hydraulic, mechanical and storage traits in 18 species in three phenological classes (readily deciduous, tardily deciduous, and evergreen) in the dry tropical forest of Chamela, Mexico. Soil water potential was negatively correlated with elevation, insolation and water flow accumulation. Evergreen species characterized low-elevation moist sites, whereas deciduous species dominated hills and dry sites. Overall, evergreen species had lower xylem specific conductivity than deciduous species, and tardily deciduous species were different from readily deciduous and evergreen species in five of eight xylem traits. In dry tropical forests, water availability promotes divergence in leaf phenology and xylem traits, ranging from low wood density, evergreen species in moist sites to a combination of low wood density, readily deciduous species plus high wood density, tardily deciduous species in dry sites.