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1.
Life-cycle studies were conducted on 2 molecular strains of Mesocestoides tapeworms that represent different evolutionary lineages (clades A and B). Wild carnivores, reptiles, and rodents were examined for tapeworm infections at 2 enzootic sites: (1) San Miguel Island (SMI), a small island off the coast of southern California and (2) Hopland Research and Extension Center (HREC), a field station in northern California. Results indicate that deer mice (Peromyscus maniculatus) and coyotes (Canis latrans) may play an important role in the life cycles of Mesocestoides (clades A and B) in California. Over half the coyotes at HREC and at least a third of the population of island fox (Urocyon littoralis) at SMI were found to harbor clade A adult Mesocestoides spp. One of every 4 Mesocestoides-infected coyotes had tapeworms representing both clades A and B. Experimental inoculations revealed that proglottids (clades A and B) were not directly infectious to rodents, reptiles, or dogs. On the other hand, mice, lizards, and hamsters fed tetrathyridia of Mesocestoides spp. (clades A or B) developed peritoneal tetrathyridial infections. A dog that was fed tetrathyridia (clade B) developed an adult tapeworm infection. Acephalic metacestodes given orally to western fence lizards, laboratory mice, or domestic dogs did not result in metacestode or adult tapeworm infections. Whereas most clade A acephalic metacestodes from dogs were asexually proliferative, clade A tetrathyridia isolated from wild deer mice did not show evidence of asexual replication. Our study supports the hypothesis that a second, as of yet unidentified, intermediate host is necessary to complete the life cycles of Mesocestoides spp., and that acephalic metacestodes represent an aberrant form, incapable of further development.  相似文献   

2.
Island foxes (Urocyon littoralis) are endemic to six of the eight California Channel Islands (USA). The island fox is classified as a threatened species by the State of California, and recently three of the six subspecies have experienced abrupt population declines. As part of a continuing effort to determine the cause of the declines, we tested island fox serum samples collected in 1988 (n = 176) and 1997-98 (n = 156) over the entire geographic range of the species for seroprevalence of canine heartworm (Dirofilaria immitis) antigen. Using a commercially available enzyme-linked immunosorbent assay (PetChek, Idexx Laboratories, Westbrook, Maine, USA) we detected heartworm antigen in four of the six populations of island foxes. On San Miguel and Santa Rosa Islands, seroprevalence in adult foxes was >85% (n = 62) in 1988 and increased to 100% (n = 24) in 1997-98. On Santa Cruz Island, seroprevalence in adult foxes decreased from 83% (n = 30) to 58% (n = 26), whereas on San Nicolas Island, seroprevalence increased from 25% (n = 32) to 77% (n = 30) during the same period. All of the pups assayed (n = 33) were seronegative. The seroprevalences of heartworm reported herein for the four populations of island foxes are the highest yet reported for a fox species. However, additional demographic data reported elsewhere suggests that heartworm has not been a major factor in the recent declines of island fox populations.  相似文献   

3.
Hematologic and serum biochemical data collected must be interpreted by comparison with normal reference intervals generated from healthy animals, within a similar population, because many blood parameters are influenced by diet, environment, and stress. Species-specific reference intervals for the endangered island fox (Urocyon littoralis) are not available. We reviewed hematology and serum biochemistry panels from 280 island foxes sampled from 1999-2008 and established normal reference intervals from clinically healthy foxes using a nonparametric approach. Blood parameters were analyzed for differences in age, sex, island of origin, and captivity status. Alkaline phosphatase, alanine aminotransferase, aspartate aminotransferase, and creatine kinase activities, as well as calcium and phosphorus concentrations, were significantly higher in juveniles than in adults, but total protein and globulin concentration was lower for juveniles than for adults. Lymphocyte and eosinophil counts, and blood urea nitrogen (BUN) concentration, in foxes from the northern Channel islands of California, USA (Santa Cruz, Santa Rosa, and San Miguel) were higher when compared with foxes from Santa Catalina Island to the south. Higher lymphocyte and eosinophil numbers in the northern island foxes may be associated with increased levels of parasitism on the northern islands. Differences in BUN concentration in both free-ranging and captive foxes may reflect dietary differences among islands. Although aggressive conservation programs have been enacted, island foxes are still susceptible to infectious and neoplastic diseases and, potentially, to toxins. Island fox species-specific reference intervals will enable managers and veterinarians to better care for sick and injured foxes and will contribute to future population health monitoring.  相似文献   

4.
The genus Mesocestoides Vaillant, 1863 includes tapeworms of uncertain phylogenetic affinities and with poorly defined life histories. We previously documented 11 cases of peritoneal cestodiasis in dogs (Canis familiaris L.) in western North America caused by metacestodes of Mesocestoides spp. In the current study, DNA sequences were obtained from metacestodes collected from these dogs (n = 10), as well as proglottids from dogs (n = 3) and coyotes (Canis latrans Say, 1823 [n = 2]), and tetrathyridia representing laboratory isolates of M. corti (n = 3), and these data were analyzed phylogenetically. Two nuclear genetic markers, 18S ribosomal DNA and the second internal-transcribed spacer (ITS 2), were sequenced. Phylogenetic analysis of the 18S rDNA data recovered a monophyletic group composed of all samples of Mesocestoides spp., distinct from closely related outgroup taxa (Amurotaenia Akhmerov, 1941 and Tetrabothrius Rudolphi, 1819). Initial analysis of the ITS 2 data resolved 3 clades within Mesocestoides. Two proglottids from dogs formed a basal clade, a second clade was represented by tetrathyridial isolates, and a third clade included all other samples. Interpretation of these data from an apomorphy-based perspective identified 6 evolutionary lineages. We also assessed whether metacestodes from dogs (n = 4) are capable of asexual proliferation in laboratory mice. One tetrathyridial and 2 acephalic isolates from dogs proliferated asexually. Further investigation is warranted to determine which of the lineages represent distinct species and to determine the life history strategies of Mesocestoides spp.  相似文献   

5.
Introduced species can cause major disruptions to ecosystems, particularly on islands. On Christmas Island, the invasive yellow crazy ant (Anoplolepis gracilipes) has detrimental impacts on many animals ranging from the iconic red crabs (Gecarcoidea natalis) to the Christmas Island Thrush (Turdus poliocephalus erythropleurus). However, the full extent of its effects on the island's fauna is not yet known. In this study, we investigated the impact of the yellow crazy ants on the island's last native mammal: the Christmas Island flying‐fox (Pteropus natalis). This species has been described as a keystone species, but has recently experienced substantial population decline to the extent that it is now listed as Critically Endangered. We examined the impacts of the yellow crazy ants on the roosting behavior of the Christmas Island flying‐fox, and on its local and island‐wide distribution patterns. We showed that the crazy ants increased behaviors in the flying‐foxes that were associated with avoidance of noxious stimuli and decreased behaviors associated with resting. Roost tree selection and roost site location were not related to variation in the abundance of crazy ants on the island. Our results indicate that the crazy ants interfere with the activity budgets of the flying‐foxes. However, the flying‐foxes failed to relocate to ant‐free roost trees or roost sites when confronted with the noxious ant, suggesting that the flying‐foxes are either not sufficiently disturbed to override strong cultural attachment to roosts, or, are behaving maladaptively due to ecological naïveté.  相似文献   

6.
The island fox (Urocyon littoralis) is native to 6 of the 8 Channel Islands of California, USA. The species experienced a population decline in the 1990s but recovered after predatory golden eagles (Aquila chrysaetos) were relocated and feral pigs (Sus scrofa), a main food source for the eagles, were removed. As part of an ongoing conservation program, the National Park Service conducts yearly health surveys on foxes residing on Santa Rosa and San Miguel islands. In this study, we document non-invasive measures of stress and nutritional status from fecal samples collected during surveys from 2009 to 2015. We collected samples defecated in traps overnight or during handling and measured concentrations of glucocorticoid (GC) and triiodothyronine (T3) metabolites using validated assays. We used generalized linear mixed models to assess the relationships between hormones, season, island, age class, sex, body condition, reproductive status, and ectoparasite presence. Overall, males had marginally lower fecal T3 concentrations than females. Concentrations of both hormones positively correlated with body condition. Fecal GC production varied seasonally; concentrations were highest from December to February and declined through the summer and fall. During summer, younger females and those with signs of recent reproduction had higher fecal GC concentrations than older females or those without evidence of reproduction. Fecal T3 concentrations did not vary in relation to season, age, or reproductive status, but on San Miguel Island were positively correlated with ectoparasite presence. There were no other significant differences between islands. Our results provide hormone data for island foxes and demonstrate that production varies in relation to seasonal and biological factors. These reference data will serve as a comparison for future health surveys and allow managers to identify factors associated with increased stress or reduced nutritional state. © 2019 The Wildlife Society.  相似文献   

7.
Serum and hematologic biochemistry values for island foxes (Urocyon littoralis) on Santa Cruz Island (California, USA) in April (wet season) and September (dry season) 1998 were evaluated. Serum chemistry of island foxes generally varied seasonally; 10 (40%) of the 25 serum characteristics were higher in the wet season, and three (12%) of the 25 serum characteristics were higher in the dry season. No hematologic parameters varied between seasons, although some measures varied between sexes. Blood analytes also varied with age; fox pups had higher values than adults for one hematologic and four serum parameters, whereas adult foxes had higher values for five hematologic characteristics. The information on blood chemistry provides baseline data useful in the monitoring of this threatened insular endemic carnivore.  相似文献   

8.
The foxes at Novosibirsk, Russia, are the only population of domesticated foxes in the world. These domesticated foxes originated from farm-bred silver foxes (Vulpes vulpes), whose genetic source is unknown. In this study we examined the origin of the domesticated strain of foxes and two other farm-bred fox populations (aggressive and unselected) maintained in Novosibirsk. To identify the phylogenetic origin of these populations we sequenced two regions of mtDNA, cytochrome b and D-loop, from 24 Novosibirsk foxes (8 foxes from each population) and compared them with corresponding sequences of native red foxes from Europe, Asia, Alaska and Western Canada, Eastern Canada, and the Western Mountains of the USA. We identified seven cytochrome b - D-loop haplotypes in Novosibirsk populations, four of which were previously observed in Eastern North America. The three remaining haplotypes differed by one or two base change from the most common haplotype in Eastern Canada. Φ(ST) analysis showed significant differentiation between Novosibirsk populations and red fox populations from all geographic regions except Eastern Canada. No haplotypes of Eurasian origin were identified in the Novosibirsk populations. These results are consistent with historical records indicating that the original breeding stock of farm-bred foxes originated from Prince Edward Island, Canada. Mitochondrial DNA data together with historical records indicate two stages in the selection of domesticated foxes: the first includes captive breeding for ~50 years with unconscious selection for behaviour; the second corresponds to over 50 further years of intensive selection for tame behaviour.  相似文献   

9.
The prevalence of Sarcocystis in white-tailed deer (Odocoileus virginianus) and mule deer (O. hemionus) in South Dakota was determined through microscopic examination of tongue samples. The percentage of Sarcocystis infection for both species of deer was determined for prairies east of the Missouri River, west of the Missouri River, and Black Hills of western South Dakota. Sixteen percent (N = 62) of the white-tailed deer tongues from East River, 69% (N = 42) from West River, and 74% (N = 23) from the Black Hills were infected. Prevalence for mule deer was 88% (N = 24), 78% (N = 63), and 75% (N = 12) from East River, West River, and the Black Hills, respectively. Of 50 tongue samples obtained from both species of deer during a special antlerless deer hunt in the Black Hills in 1978, 66% were infected. Coyotes (Canis latrans), dogs (Canis familiaris), red foxes (Vulpes vulpes), a gray fox (Urocyon cinereoargenteus), bobcat (Felis rufus), and raccoon (Procyon lotor) were fed muscle from white-tailed deer and mule deer naturally infected with Sarcocystis to determine their role as definitive hosts. All coyotes, dogs, and the gray fox shed sporocysts, while none were recovered from the other animals. Sporocysts shed by coyotes were counted and concentrated into an inoculum and administered to a white-tailed deer fawn, which was necropsied 85 days after inoculation. Sections of heart, tongue, esophagus, diaphragm, and skeletal muscle were found to be heavily infected with sarcocysts, while sarcocysts were not detected in a control fawn.  相似文献   

10.
In this study, we examined the prevalence, pathology, and epidemiology of tumors in free-ranging island foxes occurring on three islands in the California Channel Islands, USA. We found a remarkably high prevalence of ceruminous gland tumors in endangered foxes (Urocyon littoralis catalinae) occurring on Santa Catalina Island (SCA)—48.9% of the dead foxes examined from 2001–2008 had tumors in their ears, and tumors were found in 52.2% of randomly-selected mature (≥ 4 years) foxes captured in 2007–2008, representing one of the highest prevalences of tumors ever documented in a wildlife population. In contrast, no tumors were detected in foxes from San Nicolas Island or San Clemente Island, although ear mites (Otodectes cynotis), a predisposing factor for ceruminous gland tumors in dogs and cats, were highly prevalent on all three islands. On SCA, otitis externa secondary to ear mite infection was highly correlated with ceruminous gland hyperplasia (CGH), and tumors were significantly associated with the severity of CGH, ceruminous gland dysplasia, and age group (older foxes). We propose a conceptual model for the formation of ceruminous gland tumors in foxes on SCA that is based on persistent, ubiquitous infection with ear mites, and an innate, over exuberant inflammatory and hyperplastic response of SCA foxes to these mites. Foxes on SCA are now opportunistically treated with acaricides in an attempt to reduce mite infections and the morbidity and mortality associated with this highly prevalent tumor.  相似文献   

11.
The aim of this study was to compare Toxoplasma gondii infection in three canid species: red fox Vulpes vulpes, arctic fox Vulpes lagopus and raccoon dog Nyctereutesprocyonoides kept at the same farm. Anal swabs were taken from 24 adult and 10 juvenile red foxes, 12 adult arctic foxes, three adult and seven juvenile raccoon dogs. Additionally, muscle samples were taken from 10 juvenile red foxes. PCR was used to detect T. gondii DNA. T. gondii infection was not detected in any of the arctic foxes; 60% ofraccoon dogs were infected; the prevalence of the parasite in material from red fox swabs was intermediate between the prevalence observed in arctic foxes and raccoon dogs. It is possible that susceptibility and immune response to the parasite differ between the three investigated canid species. T. gondii DNA was detected in muscle tissue of five young foxes. The results of this study suggest that T. gondii infection is not rare in farmed canids.  相似文献   

12.
Recent serologic studies have identified flying foxes (Pteropus spp.) as carriers of leptospirosis; however, little is known about the role of flying foxes as carriers of pathogenic Leptospira spp. To determine if Australian Pteropus spp. are carriers of pathogenic Leptospira spp., TaqMan real-time polymerase chain reaction (PCR) was used to detect leptospiral DNA in kidney and urine specimens from four species of flying fox, including the spectacled flying fox (Pteropus conspicillatus), black flying fox (Pteropus alecto), grey-headed flying fox (Pteropus poliocephalus), and little red flying fox (Pteropus scapulatus). Of the 173 kidney samples tested, 19 (11%) were positive for leptospiral DNA. Positive individuals were detected in all four species; significant differences in prevalence were not detected between species, between species within the same geographic area, or between geographically separated samples from the same species. Of the 46 urine samples tested, 18 (39%) tested positive by PCR, confirming that flying foxes shed leptospires into the environment. The detection of leptospiral DNA in the kidneys and urine of flying foxes suggests that flying foxes are carriers of pathogenic Leptospira spp. No evidence collected in the present study, however, suggests that flying foxes pose a significant risk of leptospirosis to the wider community or that humans who are in regular, close contact with flying foxes are at risk for leptospirosis.  相似文献   

13.
Invasive predators are globally significant drivers of threatened fauna population decline and extinction, and the early detection of new incursions is critical to the chances of successful predator eradication and fauna conservation. Here, we provide evidence of the recent invasion of European red foxes (Vulpes vulpes) on to two large and internationally significant islands off the southeast coast of Queensland, Australia – Fraser Island (K'gari) and South Stradbroke Island. From camera trap footage collected on Fraser Island since 2009, foxes have now been observed on seven different occasions between 2012 and 2016. Two scats collected on South Stradbroke Island in 2013 and 2014 tested positive for fox DNA (and negative for Canis spp. DNA), with fox presence confirmed by subsequent camera trap footage in 2016. These data confirm the recent incursion of foxes on to these islands and suggest that small populations now exist there. Fraser Island and South Stradbroke Island represent key RAMSAR wetland areas of refuge for populations of multiple threatened fauna that have never been previously been exposed to foxes. Fox impacts on these fauna can only be expected to increase without management intervention to eradicate them before they become widespread.  相似文献   

14.
Large breeding populations of California sea lions (Zalophus californianus) are located on San Miguel and San Nicolas Islands in the Southern California Bight. In 2001, there was a substantial increase in pup mortality in late summer and fall. From June 2002 to January 2003, 208 freshly dead pups were examined on San Miguel Island, the most western of the Channel Islands off the coast of southern California. Tissues from 186 of these pups were examined histologically. The primary lesions in 133 (72%) of the pups were an enteritis associated with hookworms and infections in major organs. Emaciation/starvation in 43 pups (26%) was the second most important cause of death.  相似文献   

15.
The aim of this study was to examine the feces of free-ranging foxes and coyotes for the presence of Neospora caninum oocysts. Feces were collected from 271 foxes and 185 coyotes in the Canadian province of Prince Edward Island, processed by sucrose flotation, and examined by light microscopy for the presence of coccidian oocysts. In 2 fox and 2 coyote samples, oocysts morphologically and morphometrically similar to oocysts of N. caninum were observed. DNA was extracted from these samples and subjected to nested polymerase chain reaction (PCR) using primers to the N. caninum-specific Nc5 genomic sequence. Through DNA sequencing, alignment of the sequences of at least 3 clones from each isolate to sequences deposited in GenBank revealed 95-99% similarity to the Nc5 sequence of N. caninum. PCR using primers specific for Hammondia heydorni failed to yield an amplification product from these DNA samples.  相似文献   

16.
Ear mites (Otodectes cynotis) and ear canal tumors are highly prevalent among federally endangered Island foxes (Urocyon littoralis catalinae) living on Santa Catalina Island off the coast of Southern California. Since studies began in the 1990s, nearly all foxes examined were found to be infected with ear mites, and ceruminous gland tumors (carcinomas and adenomas) were detected in approximately half of all foxes ≥ 4 years of age. We hypothesized that reduction of ear mite infection would reduce otitis externa and ceruminous gland hyperplasia, a risk factor for tumor development. In this study, we conducted a randomized field trial to assess the impact of acaricide treatment on ear mite prevalence and intensity of infection, otitis externa, ceruminous gland hyperplasia, and mite-specific IgG and IgE antibody levels. Treatment was highly effective at eliminating mites and reducing otitis externa and ceruminous gland hyperplasia, and mite-specific IgG antibody levels were significantly lower among uninfected foxes. Ceruminous gland hyperplasia increased in the chronically infected, untreated foxes during the six month study. Our results provide compelling evidence that acaricide treatment is an effective means of reducing ear mites, and that mite removal in turn reduces ear lesions and mite-specific IgG antibody levels in Santa Catalina Island foxes. This study has advanced our understanding of the underlying pathogenesis which results in ceruminous gland tumors, and has helped inform management decisions that impact species conservation.  相似文献   

17.
Anti‐predator behavior can alter the dynamics of prey populations, but little is known about the rate at which anti‐predator behavior is lost from prey populations following predator removal. The Channel Islands differ in whether they have historically contained a top predator, the Island Fox (Urocyon littoralis), in evolutionary time (approximately 6200–10 000 yr). On a historically fox‐containing island and two historically fox‐free islands in 2007, I deployed live traps that contained olfactory cues of fox predators (fox feces), olfactory cues of an herbivore (horse feces) or a no‐feces control. Due to a captive breeding program, foxes on the historically fox‐containing island were effectively removed from 1998 to 2004. Rodents from one of the historically fox‐free islands did not respond to fox cues, whereas rodents on the historically fox‐containing island were more likely to be captured in a control trap and less likely to be captured in a fox‐cue trap. Results from the other historically fox‐free island that experienced a recent population bottleneck and period of captive rearing exhibited a preference for horse‐scented traps. These results suggest that, on islands where foxes are the primary predators, anti‐predator behavior in response to olfactory cues is not likely to be rapidly lost by short‐term removals of foxes, although the nature of anti‐predator behavior may depend upon founder events and recent population dynamics (e.g. population bottlenecks or several generations in captivity).  相似文献   

18.
There is a lack of information regarding the ecology and behaviour of red foxes that can be used to elaborate effective management programs for this species on Prince Edward Island (Canada). The main goal of this study was to provide baseline information on habitat selection and home range size of red foxes on Prince Edward Island. Data were collected from snow-tracking and radio-telemetry sessions conducted in two study sites (including one site within Prince Edward Island National Park). Our results indicated that red foxes selected for roads and human-use areas during both the breeding and the kit-rearing seasons in the park. Outside the park, however, the data failed to conclusively show that foxes have a unique preference for human-use habitats or roads. Forests were selected against in both study sites. Although roads are frequently visited by foxes during the kit-rearing season in the park, each individual fox typically stays in this habitat only for short periods of time (< 15 min). This finding suggests that foraging efficiency along the roads is very high possibly reflecting the abundance of anthropogenic food sources. Overall, we present the largest amount of data on habitat selection ever collected for red foxes in Prince Edward Island, Canada. Our results show that food sources in human-use areas and roads are altering the selection and/or use of habitats of red foxes in some areas of Prince Edward Island.  相似文献   

19.
We examined how large seasonal influxes of migratory prey influenced population dynamics of arctic foxes and how this varied with fluctuations in small mammal (lemming and vole) abundance—the main prey of arctic foxes throughout most of their range. Specifically, we compared how arctic fox abundance, breeding density and litter size varied inside and outside a large goose colony and in relation to annual variation in small mammal abundance. Information-theoretic model selection showed that (1) breeding density and fox abundance were 2–3 times higher inside the colony than they were outside the colony and (2) litter size, breeding density and annual variation in fox abundance in the colony tracked fluctuations in lemming abundance. The influence of lemming abundance on reproduction and abundance of arctic foxes outside the colony was inconclusive, largely because fox densities outside the colony were low, which made it difficult to detect such relationships. Lemming abundance was, thus, the main factor governing reproduction and abundance of arctic foxes in the colony, whereas seasonal influxes of geese and their eggs provided foxes with external subsidies that elevated breeding density and fox abundance above that which lemmings could support. This study highlights (1) the relative importance of migratory prey and other foods on the abundance and reproduction by local consumers and (2) how migratory animals function as vectors of nutrient transfer between distant ecosystems such as Arctic environments and wintering areas by geese thousands of kilometres to the south.  相似文献   

20.
Alveolar echinococcosis is a zoonotic infection caused by the metacestode of the tapeworm Echinococcus multilocularis. Fox populations living in the Alpine regions of Italy had been considered free from this parasite until 2002, when two infected foxes were detected in Bolzano province (Trentino Alto Adige region) near Austrian border. A modified nested PCR analysis was used to detect E. multilocularis DNA in faecal samples belonging to red fox populations from five Italian regions. A total of 522 faecal samples were analysed from foxes shot in Valle d'Aosta (N = 65), Liguria (N = 44), Lombardy (N = 105), Veneto (N = 67), and Trentino Alto Adige (N = 241) regions. Among these, 24 samples, all from the Trentino Alto Adige region, were found positive. Moreoever, 1406 faecal samples of red foxes were analyzed by CA-ELISAs commercial test kit. This paper provides an update of the epidemiological knowledge of this parasite in north Italy.  相似文献   

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