| a serologic survey of the island fox (urocyon littoralis) on the channel islands, california. | the island fox is listed as a threatened species in california. a serologic survey of 194 island foxes (urocyon littoralis) was conducted over the entire range of the species on the channel islands (california, usa). antibody prevalence against canine adenovirus and canine parvovirus reached 97% and 59%, respectively, in some populations sampled. antibody prevalence of canine herpesvirus, canine coronavirus, leptospirosis and toxoplasmosis were low. antibodies against canine distemper virus were ... | 1992 | 1318424 |
| photopigments of dogs and foxes and their implications for canid vision. | electroretinogram (erg) flicker photometry was used to examine the photopigment complements of representatives of four genera of canid: domestic dog (canis familiaris), island gray fox (urocyon littoralis), red fox (vulpes vulpes), and arctic fox (alopex lagopus). these four genera share a common cone pigment complement; each has one cone pigment with peak sensitivity of about 555 nm and a second cone pigment with peak at 430-435 nm. these pigment measurements accord well with the conclusions of ... | 1993 | 8424924 |
| spatial and temporal variation in the seroprevalence of canine heartworm antigen in the island fox. | 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 ... | 2000 | 11085434 |
| ectoparasites of the island fox on santa cruz island. | the ectoparasite fauna for island foxes (urocyon littoralis) on santa cruz island (california, usa) in april (wet season) and september (dry season) 1998 was evaluated. three taxa of ectoparasites were identified. these were fleas (pulex irritans), lice (neotrichodectes mephitidis), and ticks (ixodes pacificus). ectoparasite abundances varied seasonally. typical of insular endemic species, island foxes may be especially vulnerable to the introduction of novel disease organisms and their vectors. | 2001 | 11272496 |
| life-history studies on two molecular strains of mesocestoides (cestoda: mesocestoididae): identification of sylvatic hosts and infectivity of immature life stages. | 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 la ... | 2004 | 15040675 |
| ants as first intermediate hosts of mesocestoides on san miguel island, usa. | this study tested the hypotheses that ants (formicidae) function as a first intermediate host of mesocestoides (cestoda: mesocestoididae) and that deer mice (peromyscus maniculatus) develop metacestode infections after ingesting cysticercoid or procercoid-infected ants. field studies were conducted at an island fox (urocyon littoralis littoralis) breeding facility located on san miguel island, california channel islands national park, usa, where > 40% of captive foxes were infected with adult me ... | 2005 | 15831116 |
| double allee effects and extinction in the island fox. | an allee effect (ae) occurs in populations when individuals suffer a decrease in fitness at low densities. if a fitness component is reduced (component ae), per capita population growth rates may decline as a consequence (demographic ae) and extinction risk is increased. the island fox (urocyon littoralis) is endemic to six of the eight california channel islands. population crashes have coincided with an increase in predation by golden eagles (aquila chrysaetos). we propose that aes could rende ... | 2007 | 17650257 |
| seroprevalence of bartonella spp. in the endangered island fox (urocyon littoralis). | bartonella clarridgeiae-like strains, presently b. rochalimae, were isolated in gray foxes (urocyon cinereoargenteus) in mainland california. the objective of this study was to investigate the presence of bartonella infection in the endangered island fox (urocyon littoralis) found only on the channel islands off the californian coast. between 2001 and 2004, 263 serum samples were collected. antibodies against bartonella vinsonii subsp. berkhoffii (bvb) and b. clarridgeiae (bc) were detected usin ... | 2009 | 19058928 |
| a suspected canine distemper epidemic as the cause of a catastrophic decline in santa catalina island foxes (urocyon littoralis catalinae). | the island fox (urocyon littoralis catalinae) population on santa catalina island, california, usa declined precipitously in 1999 with an approximate 95% reduction on their eastern range, an area representing 87% of the island. during this investigation, between october 1999 and april 2000, evidence of live foxes dramatically decreased. the only carcass recovered during the decline succumbed to a co-infection of canine distemper virus (cdv) and toxoplasmosis. sequence analysis of the viral p gen ... | 2009 | 19395743 |
| does the order of invasive species removal matter? the case of the eagle and the pig. | invasive species are recognized as a primary driver of native species endangerment and their removal is often a key component of a conservation strategy. removing invasive species is not always a straightforward task, however, especially when they interact with other species in complex ways to negatively influence native species. because unintended consequences may arise if all invasive species cannot be removed simultaneously, the order of their removal is of paramount importance to ecological ... | 2009 | 19759894 |
| isolation or detection of bartonella vinsonii subspecies berkhoffii and bartonella rochalimae in the endangered island foxes (urocyon littoralis). | bartonella rochalimae (b.r.) and bartonella vinsonii subsp. berkhoffii (b.v.b.) have been isolated from gray foxes (urocyon cinereoargenteus) in mainland california and high bartonella seroprevalence was reported in island foxes (u. litorralis), especially from santa cruz and santa rosa islands. as a follow-up study, the objectives were to determine the prevalence of bartonella bacteremia and seropositivity and to identify the bartonella species infecting a convenience sample of 51 island foxes ... | 2011 | 21802869 |
| pathology and epidemiology of ceruminous gland tumors among endangered santa catalina island foxes (urocyon littoralis catalinae) in the channel islands, usa. | 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 20 ... | 2015 | 26618759 |
| induced changes in island fox (urocyon littoralis) activity do not mitigate the extinction threat posed by a novel predator. | prey response to novel predators influences the impacts on prey populations of introduced predators, bio-control efforts, and predator range expansion. predicting the impacts of novel predators on native prey requires an understanding of both predator avoidance strategies and their potential to reduce predation risk. we examine the response of island foxes (urocyon littoralis) to invasion by golden eagles (aquila chrysaetos). foxes reduced daytime activity and increased night time activity relat ... | 2011 | 20814698 |
| xenotransfusion in an island fox (urocyon littoralis clementae) using blood from a domestic dog (canis lupus familiaris). | successful xenotransfusion in an island fox ( urocyon littoralis clementae) has not been previously reported but may be necessary in an emergency. an 11-yr-old male, intact, captive island fox was exhibiting clinical signs of rattlesnake envenomation including hypoperfusion, tachypnea, facial edema, and multifocal facial and cervical ecchymosis. blood work revealed severe thrombocytopenia (18 k/μl) and anemia (hct 15.8%). a presumptive diagnosis of rattlesnake ( crotalus sp.) envenomation was ma ... | 2016 | 27691973 |
| angiocaulus gubernaculatus in the island fox (urocyon littoralis) from the california channel islands and comments on the diagnosis of angiostrongylidae nematodes in canid and mustelid hosts. | adult nematode parasites were recovered from the heart blood of a deceased island fox (urocyon littoralis) submitted for necropsy to determine the cause of death. examination of the recovered nematodes supported the generic diagnosis of angiocaulus, a parasite in angiostrongylidae found in domestic and wild canids and mustelids. specific diagnosis of the worms from the island fox as angiocaulus gubernaculatus is based on the morphology of the dorsal ray in the copulatory bursa of the male worm a ... | 2001 | 11695389 |
| [assessment of population differentiation using dna fingerprinting and modified wright's fst-statistics]. | using our results and literature data on multilocus dna fingerprinting, we propose a method of obtaining unbiased estimates of the between--population genetic similarity index and a measure of population subdivision based on modified wright's fst-statistics. on the basis of multiple comparison t2 hotelling's test and holmes' procedure, the fst-statistics was applied to assess differentiation of four (pacific and atlantic) subpopulations of humpback whale megaptera novaeangliae, six populations o ... | 2003 | 12669419 |
| does litter size variation affect models of terrestrial carnivore extinction risk and management? | individual variation in both survival and reproduction has the potential to influence extinction risk. especially for rare or threatened species, reliable population models should adequately incorporate demographic uncertainty. here, we focus on an important form of demographic stochasticity: variation in litter sizes. we use terrestrial carnivores as an example taxon, as they are frequently threatened or of economic importance. since data on intraspecific litter size variation are often sparse, ... | 2013 | 23469140 |
| genomic flatlining in the endangered island fox. | genetic studies of rare and endangered species often focus on defining and preserving genetically distinct populations, especially those having unique adaptations [1, 2]. much less attention is directed at understanding the landscape of deleterious variation, an insidious consequence of geographic isolation and the inefficiency of natural selection to eliminate harmful variants in small populations [3-5]. with population sizes of many vertebrates decreasing and isolation increasing through habit ... | 2016 | 27112291 |
| adaptive divergence despite strong genetic drift: genomic analysis of the evolutionary mechanisms causing genetic differentiation in the island fox (urocyon littoralis). | the evolutionary mechanisms generating the tremendous biodiversity of islands have long fascinated evolutionary biologists. genetic drift and divergent selection are predicted to be strong on islands and both could drive population divergence and speciation. alternatively, strong genetic drift may preclude adaptation. we conducted a genomic analysis to test the roles of genetic drift and divergent selection in causing genetic differentiation among populations of the island fox (urocyon littorali ... | 2016 | 26992010 |
| ear mite removal in the santa catalina island fox (urocyon littoralis catalinae): controlling risk factors for cancer development. | 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 reduc ... | 2015 | 26641820 |
| systemic amyloid a amyloidosis in island foxes (urocyon littoralis): severity and risk factors. | systemic amyloid a (aa) amyloidosis is highly prevalent (34%) in endangered island foxes (urocyon littoralis) and poses a risk to species recovery. although elevated serum aa (saa) from prolonged or recurrent inflammation predisposes to aa amyloidosis, additional risk factors are poorly understood. here we define the severity of glomerular and medullary renal amyloid and identify risk factors for aa amyloidosis in 321 island foxes necropsied from 1987 through 2010. in affected kidneys, amyloid m ... | 2016 | 26419399 |
| interactions between density, home range behaviors, and contact rates in the channel island fox (urocyon littoralis). | many of the mechanisms underlying density-dependent regulation of populations, including contest competition and disease spread, depend on contact among neighboring animals. understanding how variation in population density influences the frequency of contact among neighboring animals is therefore an important aspect to understanding the mechanisms underlying, and ecological consequences of, density-dependent regulation. however, contact rates are difficult to measure in the field and may be inf ... | 2015 | 26120435 |
| mitochondrial genomes suggest rapid evolution of dwarf california channel islands foxes (urocyon littoralis). | island endemics are typically differentiated from their mainland progenitors in behavior, morphology, and genetics, often resulting from long-term evolutionary change. to examine mechanisms for the origins of island endemism, we present a phylogeographic analysis of whole mitochondrial genomes from the endangered island fox (urocyon littoralis), endemic to california's channel islands, and mainland gray foxes (u. cinereoargenteus). previous genetic studies suggested that foxes first appeared on ... | 2015 | 25714775 |
| proteomic analysis of highly prevalent amyloid a amyloidosis endemic to endangered island foxes. | amyloid a (aa) amyloidosis is a debilitating, often fatal, systemic amyloid disease associated with chronic inflammation and persistently elevated serum amyloid a (saa). elevated saa is necessary but not sufficient to cause disease and the risk factors for aa amyloidosis remain poorly understood. here we identify an extraordinarily high prevalence of aa amyloidosis (34%) in a genetically isolated population of island foxes (urocyon littoralis) with concurrent chronic inflammatory diseases. amylo ... | 2014 | 25429466 |
| an island-wide predator manipulation reveals immediate and long-lasting matching of risk by prey. | anti-predator behaviour affects prey population dynamics, mediates cascading effects in food webs and influences the likelihood of rapid extinctions. predator manipulations in natural settings provide a rare opportunity to understand how prey anti-predator behaviour is affected by large-scale changes in predators. here, we couple a long-term, island-wide manipulation of an important rodent predator, the island fox (urocyon littoralis), with nearly 6 years of measurements on foraging by deer mice ... | 2014 | 24759863 |
| using population viability criteria to assess strategies to minimize disease threats for an endangered carnivore. | outbreaks of infectious disease represent serious threats to the viability of many vertebrate populations, but few studies have included quantitative evaluations of alternative approaches to the management of disease. the most prevalent management approach is monitoring for and rapid response to an epizootic. an alternative is vaccination of a subset of the free-living population (i.e., a "vaccinated core") such that some individuals are partially or fully immune in the event of an epizootic. we ... | 2013 | 23521669 |
| conservation strategies for species affected by apparent competition. | apparent competition is an indirect interaction between 2 or more prey species through a shared predator, and it is increasingly recognized as a mechanism of the decline and extinction of many species. through case studies, we evaluated the effectiveness of 4 management strategies for species affected by apparent competition: predator control, reduction in the abundances of alternate prey, simultaneous control of predators and alternate prey, and no active management of predators or alternate pr ... | 2013 | 23282104 |
| biochemical and hematologic reference intervals for the endangered island fox (urocyon littoralis). | 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 interva ... | 2012 | 22740524 |
| high mhc diversity maintained by balancing selection in an otherwise genetically monomorphic mammal. | the san nicolas island fox (urocyon littoralis dickeyi) is genetically the most monomorphic sexually reproducing animal population yet reported and has no variation in hypervariable genetic markers. such low levels of variation imply lower resistance to pathogens, reduced fitness, and problems in distinguishing kin from non-kin. in vertebrates, the mhc contains genes that influence disease resistance and kin recognition and may be under intense balancing selection in some populations. hence, gen ... | 2004 | 14990802 |
| hematology and serum chemistry of the island fox on santa cruz island. | 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. bloo ... | 2000 | 10813627 |
| the use of microsatellite variation to infer population structure and demographic history in a natural model system. | to assess the reliability of genetic markers it is important to compare inferences that are based on them to a priori expectations. in this article we present an analysis of microsatellite variation within and among populations of island foxes (urocyon littoralis) on california's channel islands. we first show that microsatellite variation at a moderate number of loci (19) can provide an essentially perfect description of the boundaries between populations and an accurate representation of their ... | 1999 | 9927470 |
| a morphologic and genetic study of the island fox, urocyon littoralis. | the island fox, urocyon littoralis, is a dwarf form found on six of the channel islands located 30-98 km off the coast of southern california. the island populations differ in two variables that affect genetic variation: effective population size and duration of isolation. we estimate that the effective population size of foxes on the islands varies from approximately 150 to 1,000 individuals. archeological and geological evidence suggests that foxes likely arrived on the three northern islands ... | 1991 | 28563958 |
| genetic fingerprinting reflects population differentiation in the california channel island fox. | restriction fragment profiles generated by hybridization of hypervariable minisatellite dna probes have been used for paternity analysis but not for comparisons at the level of populations, because the profiles are thought to evolve too rapidly to be informative over large time intervals. but in small isolated populations, the fixation of restriction-fragment polymorphisms can outpace the generation of fragment-length variability through recombination. here we report on an analysis of dna finger ... | 1990 | 1970419 |
| two's company, three's a crowd: exploring how host-parasite-microbiota interactions may influence disease susceptibility and conservation of wildlife. | a large body of research has demonstrated that host-associated microbiota-the archaeal, bacterial, fungal and viral communities residing on and inside organisms-are critical to host health (cho & blaser, 2012). although the vast majority of these studies focus on humans or model organisms in laboratory settings (pascoe, hauffe, marchesi, & perkins, 2017), they nevertheless provide important conceptual evidence that the disruption of host-associated microbial communities (termed "dysbiosis") amon ... | 2020 | 32115825 |
| ear mite infection is associated with altered microbial communities in genetically depauperate santa catalina island foxes (urocyon littoralis catalinae). | the host-associated microbiome is increasingly recognized as a critical player in health and immunity. recent studies have shown that disruption of commensal microbial communities can contribute to disease pathogenesis and severity. santa catalina island foxes (urocyon littoralis catalinae) present a compelling system in which to examine microbial dynamics in wildlife due to their depauperate genomic structure and extremely high prevalence of ceruminous gland tumors. although the precise cause i ... | 2020 | 31821650 |
| purging of strongly deleterious mutations explains long-term persistence and absence of inbreeding depression in island foxes. | the recovery and persistence of rare and endangered species are often threatened by genetic factors, such as the accumulation of deleterious mutations, loss of adaptive potential, and inbreeding depression [1]. island foxes (urocyon littoralis), the dwarfed descendants of mainland gray foxes (urocyon cinereoargenteus), have inhabited california's channel islands for >9,000 years [2-4]. previous genomic analyses revealed that island foxes have exceptionally low levels of diversity and elevated le ... | 2018 | 30415705 |
| impacts of heterogeneous host densities and contact rates on pathogen transmission in the channel island fox (urocyon littoralis). | diseases threaten wildlife populations worldwide and have caused severe declines resulting in host species being listed as threatened or endangered. the risk of a widespread epidemic is especially high when pathogens are introduced to naive host populations, often leading to high morbidity and mortality. prevention and control of these epidemics is based on knowledge of what drives pathogen transmission among hosts. previous disease outbreaks suggest the spread of directly transmitted pathogens ... | 2019 | 32831352 |
| vaccination and monitoring strategies for epidemic prevention and detection in the channel island fox (urocyon littoralis). | disease transmission and epidemic prevention are top conservation concerns for wildlife managers, especially for small, isolated populations. previous studies have shown that the course of an epidemic within a heterogeneous host population is strongly influenced by whether pathogens are introduced to regions of relatively high or low host densities. this raises the question of how disease monitoring and vaccination programs are influenced by spatial heterogeneity in host distributions. we addres ... | 2020 | 32421723 |
| pathogen exposure in endangered island fox (urocyon littoralis) populations: implications for conservation management. | island fox (urocyon littoralis) populations on four california channel islands have declined severely since 1994. canine distemper (cdv) was suspected to be responsible for the decline of the santa catalina island fox, so knowledge of infectious disease exposure in the remaining island fox populations was urgently needed. this study reviewed previous pathogen exposure in island foxes and investigated the current threat by conducting a serologic survey of foxes on all islands and sympatric feral ... | 2006 | 32226080 |