Care, management, and biology of captive striped skunks (Mephitis mephitis).

The striped skunk has a number of characteristics that make it one of the most desirable wild carnivores for scientific study. This paper described in detail the care and management of this species in captivity. Reproduction and factors which may affect productivity were discussed, including: duration of mating period, experience, and age of the female. Two optimal mating periods resulted in the greatest productivity and survival of young: (1) 24 hours and (2) 24 hours followed by another mating of equal duration 2 or 3 da later. Experienced females required fewer matings, conceived earlier, and had larger litters than their inexperienced counterparts. Captive skunks conceived as early as mid-February; births occurred in May or June with litters averaging 4.17 pups per litter. Females produced their maximum number of young at age 2 and had a progressive decline in mean litter size after this age. Measurements of growth and development of the young up to 32 da were included. A descenting method used in descenting nearly 300 pups was described. Mortality was high during the first 2 mo of life, with only 59.81% (192/321) of the pups surviving until weaning. Sixteen different pathologic conditions confirmed by necropsy were listed. The signs of canine distemper in the striped skunk were described.     

Polymorphic microsatellite markers for the striped skunk, Mephitis mephitis, and other mephitids

We report 10 polymorphic microsatellite loci primers developed for striped skunks (Mephitis mephitis), a widespread mesocarnivore in North America. Numbers of alleles in these loci ranged from seven to 14 and the observed heterozygosity ranged from 0.76 to 1.0. These primers will be useful for studying population dynamics of skunks where rabies is endemic and will be useful to estimate genetic relatedness among females sharing winter dens. Most of these primers amplify across species within the Mephitidae.     

Ontogeny and sexual dimorphism in a captive population of juvenile striped skunks <Emphasis Type="Italic">Mephitis mephitis</Emphasis>

Three main hypotheses can explain the origin of the sexual size dimorphism: (1) the birth-size hypothesis, which states that birth size of males is larger than that of females; (2) the growth-rate hypothesis, which states that males grow faster than females; (3) the growth-length hypothesis, which states that males grow for a longer period of time than females. We examined the factors that may contribute to sexual size dimorphism with growth data of striped skunks Mephitis mephitis Schreber, 1776 held in captivity in Manitoba (Canada), from 7 to 72 days of age. At seven days of age, the mass of male skunks (mean = 79.7 g ± 13.9 SE, n = 37) was significantly larger than that of females (mean = 71.2 g ± 15.0 SE, n = 35) but the head and body length was not statistically different between males (mean = 110.3 mm ± 8.0 SE, n = 37) and females (mean = 95.3 mm ± 7.4 SE, n = 35). There was no difference in growth rate for mass or for length between sexes. We were not able to test for a difference in growth length between sexes. Our results suggest that mass dimorphism occurs early in life.     

Energetic consequences and ecological significance of heterothermy and social thermoregulation in striped skunks (Mephitis mephitis)

We assessed patterns and energetic consequences of different overwintering strategies, torpor, and social thermoregulation in the striped skunk (Mephitis mephitis) under natural ambient temperature and photoperiod. Striped skunks entered spontaneous daily torpor, with the lowest torpid body temperature (T(b)) reaching 26.0 degrees C, the lowest recorded T(b) for a carnivore. Patterns of daily torpor differed between solitary and grouped skunks: all solitary skunks regularly entered daily torpor, but only some individuals in communal dens employed torpor. When they did, it was shallow and infrequent. Solitary skunks entered torpor on average 50 times (in 120 d) compared with 6 times for grouped skunks. During torpor, solitary skunks had average minimum T(b) of 26.8 degrees C and bout duration of 7.8 h, whereas grouped skunks had average minimum T(b) of 30.9 degrees C and bout duration of 5.4 h. Torpor by solitary skunks occurred during their activity phase, but grouped skunks' shallow torpor bouts were restricted to their diurnal resting phase. On average, grouped skunks experienced lower percent daily fat loss, and they emerged in spring with higher percent body fat of 25.5%. In contrast, solitary skunks emerged in spring with only 9.3% body fat. In conclusion, the use of daily torpor and social thermoregulation in northern populations of striped skunks represent two strikingly different mechanisms to minimize energetic costs and increase individual fitness in response to unfavorable environmental conditions.     

Reproductive parameters of the common genet <Emphasis Type="Italic">Genetta genetta</Emphasis> (Linnaeus, 1758) in Southwest Europe

We used information from 148 litters belonging to 119 different wild and captive female common genets (Genetta genetta) in SW Europe over a period of almost 50 years to study certain reproductive parameters. Data were obtained from a combination of sources including carcasses, live captures, telemetry-based studies, captive genets, and reports in the literature. The circannual pattern of breeding was fairly similar in both wild and captive genets, with births occurring in all months except December, albeit with a large peak in spring and a secondary peak in autumn. The sex ratio at birth was near to 1:1, and mean litter size was 2.16 ± 0.76 cubs/litter with a range of 1–5 cubs. Litters of two cubs were the most frequent both in wild and captive settings. In captivity, we have observed the births of replacement litters and double litters; however, we did not find evidence of wild females that having two litters in the same year. We conclude that the possibility of breeding at any time of the year is facilitated by the continuous spermatogenesis of the males and by the ability of females to enter into estrus after losing a litter prematurely and to breed twice in the same year.     

Behavior, movements, and demographics of rabid raccoons in Ontario, Canada: management implications

During 1999-2003, 127 cases of raccoon variant rabies were reported in raccoons (Procyon lotor) and striped skunks (Mephitis mephitis) in Ontario, Canada. Raccoons accounted for 98% (125/127) of the reported cases with behaviors/conditions including aggression, fighting with dogs, ataxia, vocalizations, appearance of being sick, and the presence of porcupine (Erethizon dorsatum) quills. Seventy-eight percent of the rabid raccoons were adults. Juveniles were underrepresented (22%) compared with the adult/juvenile ratios found in nonrabid Ontario raccoon populations. Of the known aged raccoons, 83% were < or = 3 yr of age, and 22% of the rabid adult female raccoons had evidence of having had a litter during the year in which they were found to be rabid. The majority of rabid raccoons were reported during the fall, winter, and spring, suggesting a relationship between raccoon behavioral activities such as denning and breeding and the timing of rabies outbreaks. Multiple cases of raccoon rabies occurred at several barns, suggesting that those structures serve as focal points of rabies transmission as a result of denning activities. Movements of five rabid raccoons (range 1,564-4,143 m) were not different from movements of nonrabid raccoons in Ontario. Sixty-six percent of the rabid animals were submitted by government staff, stressing the importance of those agencies in rabies control and surveillance operations. Increased knowledge of the behaviors of rabid raccoons should assist in the development of management strategies for rabies.     

ACCLIMATION TO CAPTIVITY: A QUANTITATIVE ESTIMATE BASED ON SURVIVAL OF BOTTLENOSE DOLPHINS AND CALIFORNIA SEA LIONS

An estimate of how long marine mammals need to acclimate to captivity would permit more precise comparisons of husbandry practices, yet no quantitative analysis of acclimation has been performed. Therefore, we estimated the duration of acclimation to captivity for bottlenose dolphins (BD) and California sea lions (CSL) by comparing 5-d survival rates during the first 90 d of captivity with a survival rate based on days 91-365 in captivity. Wild-born BD (n = 1,270) and CSL (n = 1,650) acclimate to captivity in approximately 35 and 40 d, respectively, whereas captive born BD (n = 332) and CSL (n = 992) acclimate in approximately 50 and 40 d, respectively. When transferred between two institutions, BD (n = 911) acclimated in the same amount of time (45 d) as when first transferred from the wild, whereas transferred CSL (n = 336) acclimated more rapidly (15 VJ. 40 d) than when first transferred from the wild. Based on results from these two species, a 60-d acclimation period is recognized as a distinct interval of relatively high mortality that should be treated separately from long-term survival estimates when evaluating husbandry practices of ocean-aria and zoos.     

Streptococcus equisimilis infection in striped skunks (Mephitis mephitis) in Saskatchewan

Three radio-collared striped skunks (Mephitis mephitis) found dead during a field study of winter ecology of striped skunks near Willowbrook, Saskatchewan, Canada were examined. Streptococcus equisimilis was identified as the primary agent causing necrotizing purulent pneumonia in one skunk and suppurative meningoencephalitis in another. Both Streptococcus equisimilis and Streptococcus canis were isolated from lesions of purulent myocarditis and pyothorax in the third skunk. These are apparently the first reported cases of S. equisimilis infection in striped skunks and suggest that this opportunistic pathogen may be a significant cause of mortality under some conditions.     

Captive husbandry of stoats Mustela erminea

Abstract

Captive stoats are essential for testing technological developments for pest control in New Zealand. We have reviewed husbandry practices and experiences of keeping stoats in captivity for a range of purposes. Stoats can be kept individually outside and subjected to normal regimes of light and temperature if sufficient bedding and shelter is provided. They appear to survive and breed best when fed on freshly killed rodents. Live prey is desirable though will rarely be permissible due to regulatory constraints. Breeding in captivity has been problematic in most cases, and although in a few instances wild‐caught females carrying embryos in delay have given birth, this is a rare event. Procedures taken to minimise stress in captivity may reduce the loss rate of blastocysts due to resorption and facilitate rapid expansion of captive colonies.     

Density-dependent predation by skunks using olfactory search images

The formation of search images can create density-dependent predation. Predators have been shown to form search images when searching for many small prey items in one feeding session. This paper reports experiments that test whether striped skunks can form olfactory search images in other situations: when prey are found over several days, when prey are large, and when prey are found in certain habitats. Striped skunks were raised in captivity, and their reaction distance to food was measured outside in a natural grassy area. In experiment 1 skunks were offered many small food items for several days in a row. From one day to the next, skunks initially detected food from further away, they increased detection distance faster and their maximum detection distance increased – i.e., they formed olfactory search images faster and stronger from one day to the next. In experiment 2 skunks formed search images over several days when finding only one large food item per day. In experiment 3 skunks lost olfactory search images when they entered habitats in which they had previously searched for another type of food. These long-term search images magnify the effects of short-term search images, extend the effects of short- term search image to longer time spans, and affect different species from short-term search images. Received: 26 July 1996 / Accepted: 13 December 1996     

Ovarian cycle and egg production of the western swamp tortoise Pseudemydura umbrina (Testudines: Chelidae) in the wild and in captivity

The reproductive organs of logn-term captive females and of wild females of the western swamp tortoise, Pseudemydura umbrina , which were taken temporarily into captivity, were studied over several years by ultra-sound scanning. Pseudemydura umbrina , a critically-endangered species, is active during winter and spring when the ephemeral swamps it inhabits contain water and aestivates during summer and autumn (November to May/June) when the swamps are dry. The vitellogenic growth of ovarian follicles commences during aestivation in summer and continues during autumn and winter. The timing of the vitellogenic cycle is remarkably similar to that of many other Australian chelids and that of many other chelonians of temperate and subtropical regions, but the patterns of energy harvest, storage and allocation to ovarian follicles is different. Ovulation occurs between late September and early November and is preceded by a feeding bout and a sharp increase in female body mass. One clutch of 3–5 eggs (exceptionally of one or two) is laid in November/December. Sub-adult females show cycles of follicular growth, followed by atresia, for several years before ovulating and laying eggs. Females taken into captivity may miss the following vitelogenic cycle, but captivity does not generally affect vitellogenic cycles. Ovulation and egg production of captive animals is easily suppressed, however, under stress or sub-optimal food intake in spring. The sensitivity of ovulation to sub-optimal conditions and the subsequent reabsorption of the yolk material may enhance survival of the reproducing individual during long dry periods in an unpredictable environment.     

Cotton-top tamarins (Saguinus (o.) oedipus) in a semi-naturalistic captive colony

To test the prediction that the breeding success of captive cotton-top tamarins (Saguinus (o.) oedipus) could be improved by maintaining them in groups whose size and age-sex composition resembled those of wild groups, data were collated from 6.5 years of records from a breeding colony that otherwise had housing and husbandry procedures similar to those of other successful colonies. Group size and composition in the colony closely resembled those of wild groups, and infant survival was the highest yet reported for the species, with 69% of the 124 infants born reared by their parents to adulthood, and a mean surviving litter size of 1.5 infants. Abortion, stillbirth, and parental neglect of infants were rare. Parity had several effects on reproduction: mean litter size decreased, but percentage infant survival increased; interbirth intervals decreased in length; and seasonality in reproduction was more pronounced for the first four litters born to breeding females than for their subsequent litters, with a birth peak in the spring. Although a spacious and complex physical environment, retention of offspring in their natal families until experience of several sets of infant siblings had been obtained, and non-invasive husbandry and research techniques may all have contributed to the colony's success, it seems possible that the improvement over other colonies is due to the resemblance of group composition to those of wild tamarins.     

Aposematic Behaviour in the Striped Skunk,Mephitis mephitis

From April to August, 1993 to 1995, we studied the aposematic behaviour patterns of striped skunks, Mephitis mephitis, incidentally while ground-tracking radio-marked animals. During 2668 h of tracking, 207 defensive postures were displayed by 34 radio-collared (27 females, 7 males) and 21 unidentified skunks. Skunks most often advertised their noxiousness using Tail-up (69.1 % occurrence) and Stomp (17.4%). Encounters were frequently (42.5 %) terminated by the skunk running away from the source of disturbance. Most warning behaviour was directed at radio-trackers (95.7 %), and the remainder was displayed to a variety of predatory and non-predatory animals or objects. Stomp occurred more frequently in taller vegetation, where visual advertisement was limited. Reaction distance of skunks disturbed by observers (median = 6 m) was not affected by wind, movement or vegetation height. The small awareness circle and high tolerance of skunks to disturbance are consistent with the life history traits of aposematic animals.     

Helminths of sympatric striped, hog-nosed, and spotted skunks in west-central Texas

Twenty-eight hog-nosed skunks (Conepatus leuconotus), 23 striped skunks (Mephitis mephitis), and nine spotted skunks (Spilogale gracilis) from an area of sympatry in west-central Texas were examined for helminth parasites. Shared helminth species among all three host species were one nematode (Physaloptera maxillaris), two acanthocephalans (Pachysentis canicola, Macracanthorhynchus ingens), and one cestode (Mathevotaenia mephitis). Two nematodes (Gongylonema sp. and Filaria taxidaea) occurred in both the striped and hog-nosed skunks. One nematode (Filaroides milksi) and one acanthocephalan (Oncicola canis) were collected only from C. leuconotus. The most common helminth infections for striped and hog-nosed skunks were P. maxillaris and P. canicola. Helminth species richness was highest in hog-nosed skunks, but striped skunks had the highest prevalences and intensities of all the common helminth species. The helminth fauna of spotted skunks was markedly depauperate in terms of species richness and helminth abundance compared to the other two host species. Differences in helminth communities across these three sympatric skunks may be related to differences in their relative abundance, behavior, food habits, and geographic range.     

The susceptibility of five species of wild animals to experimental infection with Leptospira grippotyphosa

Five species of wild animals including opossums, Didelphis marsupialis, striped skunks, Mephitis mephitis, red, Vulpes vulpes, and gray foxes, Urocyon cinereoargenteus and raccoons, Procyon lotor, were inoculated intraperitoneally with varying numbers of Leptospira grippotyphosa, organisms. Clinical signs were not detected, however, leptospiremia, leptospiruria and antibodies for the homologous organism, were demonstrated. Lesions attributed to leptospirosis were observed in liver and kidney tissue of infected animals. Infections were demonstrated in 5 of 9 opossums, 3 of 9 striped skunks, 3 of 9 red foxes, none of the gray foxes, and 9 of 9 raccoons. Therefore, it would appear that under conditions of this experiment that raccoons were most, opossums moderately, and skunks and red foxes least susceptible; gray foxes were not susceptible.     

Bimodal annual reproductive pattern in laboratory-reared marbled crayfish

The marbled crayfish, Procambarus fallax f. virginalis, is a new research model and potent invader of aquatic ecosystems that reproduces by obligatory parthenogenesis. My data show that in captivity, it can reproduce throughout the year. However, when kept at constant 20 °C and natural photoperiod there were two prominent spawning maxima, one before the spring equinox and another one before the fall equinox. If temperature fluctuated between ~15 °C in winter and ~25 °C in summer, the first maximum was shifted beyond the spring equinox and the second maximum was shifted closer towards the fall equinox. These results indicate a bimodal annual rhythm for the reproduction in marbled crayfish that can be modulated by temperature. Comparison with P. fallax suggests that this rhythmicity was inherited from its sexually reproducing mother species. Potential consequences of my laboratory findings for wild populations of marbled crayfish in temperate and tropical regions are discussed. Since marbled crayfish can be kept in captivity for up to four years under a broad range of conditions, they offer the possibility to investigate endogenous circannual rhythms and their entrainment by environmental zeitgebers in decapod crustaceans.     

Calomys laucha (Rodentia, Cricetidae): growth and breeding in laboratory conditions

The husbandry and breeding of Calomys laucha (Rodentia, Cricetidae) in captivity are described. Growth curves based on body weight and length showed statistical differences between sexes after 45 days, males being heavier than females. The overall reproductive efficiency was 53.4% but birth rate was depressed during winter. Gestation length was 21 +/- 1 days and females exhibited postpartum oestrus with a 3-7 day implantation delay (51%). Litter size was 5.3 +/- 1.1 (n = 34). Pup survival at weaning was 84.9%. Mean life span in laboratory conditions was 13.5 months and a cumulative mortality of 90% was reached at 27-28 months of age.     

Seroprevalence of Toxoplasma gondii in mesocarnivores of the Canadian prairies

The protozoon Toxoplasma gondii has a worldwide distribution and affects many species of warm-blooded animals. In the Canadian prairies, mesocarnivores such as striped skunks (Mephitis mephitis) and raccoons (Procyon lotor) have experienced an increase in density and distribution, and they are in close contact with human dwellings. However, there has been no systematic study on the seroprevalence of T. gondii in these mesocarnivore populations. The objectives of the current project were to determine the serum antibody prevalence of T. gondii in Canadian prairie mesocarnivores and to study the relationship between antibody prevalence and species, sex, age, location, and year of collection. Antibodies to T. gondii were found in 5 of 24 (20.8%) skunks from Saskatchewan trapped in 1999 and 5 of 40 (12.5%) in 2000. Seroprevalences for T. gondii in raccoons and skunks trapped in Manitoba were 2 of 10 (20%) raccoons trapped in 2002, 7 of 44 (15.9%) trapped in 2003, and 16 of 37 (43.2%) trapped in 2004; and in 13 of 99 (13.1%) skunks trapped in 2003, 29 of 131 (22.1%) trapped in 2004, 53 of 165 (32.1%) trapped in 2005, and 30 of 51 (58.8%) trapped in 2006. Age, location, and year, but not the host species, were important variables in the determining the seroprevalence of T. gondii in skunks and raccoons. Results confirm that T. gondii is endemic in the skunk and raccoon populations in the Canadian prairies.     

Seasonal variation in fertility, fecundity and litter sex ratio in laboratory and wild stocks of house mice (Mus domesticus)

Data compilations were made for three parameters pertaining to reproduction in a domestic strain (14 years) and a wild stock (4 years) of commensal house mice: (a) the percentage of females mated that produced litters; (b) the average number of pups per litter; and (c) the sex ratio of the pups in the litters. Fecundity and fertility varied seasonally in both domestic and wild mice. More females become pregnant and litter sizes were larger in the spring, summer, and fall months than during the winter season. Sex ratios also varied seasonally with more male biased litters produced during the 4 winter months. There appear to be seasonal shifts in productivity for both stocks of mice and these seasonal trends have not been altered by domestication under laboratory conditions. In spite of the fact that house mice are generally opportunistic, it is possible that there has been selection in the mice for shifting rates of production in relation to the best seasons of the year in terms of climate and resource availability. The higher production of males during summer months may be geared toward greater success in dispersal at that season and a higher probability that the males can find a territory and mate successfully in summer rather than winter. These results have potential implications for animal breeders and for those who maintain mouse colonies to produce animals for scientific investigations.     

The effect of long non-reproductive periods on the genital health in captive female white rhinoceroses (Ceratotherium simum simum, C.s. cottoni)

White rhinoceroses suffer from a low reproductive rate in captivity. Intensive efforts to propagate specifically the northern white rhinoceros have been very limited. The dismal outlook for this subspecies in the wild makes successful ex situ breeding programs paramount. In this context, this study examined 48 southern and 6 northern white rhinoceroses using ultrasound and faecal hormone analysis to elucidate causes for female reproductive failure and to determine whether long non-reproductive periods have a detrimental impact on genital health. Results showed that 76% of the nulliparous females had intact hymenal membrane indicating these females had never been bred, at an age when their wild counterparts have delivered multiple offspring. Fifty-six percent of the studied population had various reproductive pathology. Cystic endometrial hyperplasia; leiomyomas of the cervix, uterus and ovary, adenoma; para-ovarian cysts and hydromucometra represent the scope of lesions identified. The stages of the lesions in nulliparous females correlated with age (r = 0.4, P < 0.05). Due to the severity of the lesions, 28% of the study population was considered post-reproductive. Therefore, the reproductive life span in some individuals was 10-20 years shorter than expected. However, in parous females the incidence of pathological lesions was significantly lower (P < 0.0001). Seventy-eight percent females studied had erratic or absent luteal activity. The hormone data corresponded with two ultrasonographic levels of ovarian activity, active and inactive, occurring within an age range of 3-19 years and 15-38 years, respectively. This suggests the lack of ovarian activity by reproductive mid-life in non-reproducing females. The accuracy of the ultrasound findings was validated by necropsy in nine animals showing a strong positive correlation (r2 = 0.9, p < 0.001). Our data suggests that the development of reproductive pathology and ovarian inactivity in white rhinoceros is an age-related consequence of long non-reproductive periods. This asymmetric ageing process of the genital organs can be prevented with the achievement of at least one pregnancy.