Diet reveals potential for competition and coexistence among coyotes (Canis latrans), red foxes (Vulpes vulpes), and gray foxes (Urocyon cinereoargenteus)

Species can alleviate competition by reducing diet overlap. Nonnative coyotes (Canis latrans (Say, 1823)) and historically native gray foxes (Urocyon cinereoargenteus (Schreber, 1775)) have expanded their ranges and may compete with native red foxes (Vulpes vulpes (Linnaeus, 1758)). To examine potential competition among canids in Maine, we compared δ13C and δ15N from muscle and hair samples to assess relative resource use, and we compared frequency of occurrence of prey items from stomach contents to assess diets. For these species, red foxes consumed anthropogenically-based foods the most in fall-early winter, gray foxes consumed anthropogenically-based foods the most in summer, and coyotes consumed anthropogenically-based foods the least in all seasons. Coyotes held the highest relative trophic position in fall-early winter, red foxes held the highest relative trophic position in summer, and gray foxes held the lowest relative trophic position. Based on stomach contents, gray foxes had the broadest diet and consumed the most plants, and coyotes had the narrowest diet. Red foxes were the only species to show isotopic niche overlap with both potential competitors across seasons. Thus they may be most susceptible to competitive exclusion among these canids, with implications for community dynamics as ranges shift due to human activity.

Spatial ecological interactions between coyote and gray fox in a temperate forest

Coyotes (Canis latrans) and gray foxes (Urocyon cinereoargenteus) are abundant and widely distributed in México, with no information currently available about their spatial interactions in the country. Our objectives were to evaluate the habitat use of these species and the environmental interactions between them throughout the overlapping areas of their home ranges in temperate forests of Durango, México. We expected that their coexistence would be facilitated by the spatial segregation of their ecological niche, exhibited by the low or nil overlap between their home ranges or by differentiated habitat use. Radio-collars (VHF) were attached to nine individuals — four coyotes (two males and two females) and five gray foxes (females) — that were radio-tracked from September 2017 to August 2019. We estimated their home ranges and the size of their core areas through the minimum convex polygon and determined the extent of overlap between them. Also, we evaluated third-order habitat selection and use based on habitat availability using Manly’s habitat-selection ratios and simultaneous Bonferroni confidence intervals (95 %). The mean home range size for coyotes was larger (12.2 ± 1.74 km2) than for gray boxes (5.3 ± 0.67 km2); the interspecific mean overlap was 42 % (moderate). Of these two canids, just the gray fox showed a markedly selective habitat use. Our findings revealed a moderate overlap between the home ranges of both canids, so spatial segregation did not occur. Although a differential habitat use was observed, explaining the coexistence between these two canids in the areas where they thrive, they tend to avoid agonistic interactions.

Limitations of current knowledge about the ecology of Grey Foxes hamper conservation efforts

Species-specific conservation is important for maintaining the integrity of ecological communities but is dependent on sufficiently understanding multiple aspects of a species’ ecology. Species-specific data are commonly lacking for species in geographic areas with little research and species perceived to have insufficient charisma or economic importance. Despite their widespread distribution across central and North America and status as a furbearing mammal, little is known about the ecology of Grey Foxes Urocyon cinereoargenteus compared to other species of furbearing mammals. To understand what is known about this species, especially factors affecting population dynamics, we performed a systematic review of the scientific literature. We found 234 studies about Grey Foxes, with studies increasing substantially over time but with geographic gaps in the Great Plains and most of Mexico and central America. Most studies we reviewed examined relative abundance or occupancy (n= 35), habitat associations (n= 30), primarily as part of larger mammalian community studies, or spatiotemporal effects of other mammalian carnivores (n= 19), predominately Coyote Canis latrans. Grey Foxes were primarily forest-associated although associations with specific forest communities or anthropogenically disturbed habitats varied among studies. Multiple studies across ecoregions reported this fox as among both the most- and least-abundant mammalian carnivore. The inter-specific effects of Coyote were often, but not exclusively, negative and were likely mediated by landscape composition and human development. Importantly, very few studies examined population-effects of coyotes on Grey Foxes. Studies of population trends, demographics, and space use of Grey Foxes were comparatively rare and small inter- and intra-study sample sizes limited our ability to infer broader patterns. We suggest multiple avenues for future research to better understand the population status of this species throughout their range.

First record of the coexistence of two mesocarnivores in the Yucatán Peninsula, México

La ocurrencia de dos o más especies en espacio y tiempo (coexistencia) es la condición inicial para las interacciones interespecíficas. Por ejemplo, el binomio Urocyon cinereoargenteus y Spilogale angustifrons que es poco conocido. Nuestro objetivo es contribuir con información sobre la coexistencia de estos mesocarnívoros en Komchén de los Pájaros, en el norte de Yucatán, dominada por selva baja caducifolia. Colocamos ocho cámaras-trampas del 23 de diciembre de 2019 al 20 de junio de 2020 distribuidas en ocho estaciones de muestreo. Representamos los patrones de actividad diaria mediante un diagrama circular por horas con base en la frecuencia de los registros fotográficos. Obtuvimos 68 foto-registros con un esfuerzo de muestreo de 4,320 hr-trampa en 180 días, tres corresponden a la coexistencia de U. cinereoargenteus y S. angustifrons. La actividad de U. cinereoargenteus ocurrió todo el día durante la temporada seca. El índice de abundancia relativa de la coexistencia de S. angustifrons-U. cinereoargenteus fue de 0.7 y solo para U. cinereoargenteus fue de 15.74. En tres momentos registramos la sincronización de la actividad de U. cinereoargenteus y S. angustifrons. Estos eventos ocurrieron en la noche, madrugada y al amanecer, lo que confirmó la coexistencia de ambas especies en espacio (selva baja caducifolia) y tiempo (temporada de seca). Los registros fotográficos no mostraron eventos antagónicos y el seguimiento de una especie por la otra sugiere un mutualismo. Confirmamos la coexistencia basada en el comportamiento de seguimiento de U. cinereoargenteus por S. angustifrons y planteamos que son especies mutualistas en temporada seca y en la selva baja caducifolia.

Mitochondrial Genomes of the United States Distribution of Gray Fox (Urocyon cinereoargenteus) Reveal a Major Phylogeographic Break at the Great Plains Suture Zone

We examined phylogeographic structure in gray fox (Urocyon cinereoargenteus) across the United States to identify the location of secondary contact zone(s) between eastern and western lineages and investigate the possibility of additional cryptic intraspecific divergences. We generated and analyzed complete mitochondrial genome sequence data from 75 samples and partial control region mitochondrial DNA sequences from 378 samples to investigate levels of genetic diversity and structure through population- and individual-based analyses including estimates of divergence (FST and SAMOVA), median joining networks, and phylogenies. We used complete mitochondrial genomes to infer phylogenetic relationships and date divergence times of major lineages of Urocyon in the United States. Despite broad-scale sampling, we did not recover additional major lineages of Urocyon within the United States, but identified a deep east-west split (∼0.8 million years) with secondary contact at the Great Plains Suture Zone and confirmed the Channel Island fox (Urocyon littoralis) is nested within U. cinereoargenteus. Genetic diversity declined at northern latitudes in the eastern United States, a pattern concordant with post-glacial recolonization and range expansion. Beyond the east-west divergence, morphologically-based subspecies did not form monophyletic groups, though unique haplotypes were often geographically limited. Gray foxes in the United States displayed a deep, cryptic divergence suggesting taxonomic revision is needed. Secondary contact at a common phylogeographic break, the Great Plains Suture Zone, where environmental variables show a sharp cline, suggests ongoing evolutionary processes may reinforce this divergence. Follow-up study with nuclear markers should investigate whether hybridization is occurring along the suture zone and characterize contemporary population structure to help identify conservation units. Comparative work on other wide-ranging carnivores in the region should test whether similar evolutionary patterns and processes are occurring.

FRECUENCIA DE ANTICUERPOS CONTRA TOXOPLASMA GONDII EN CARNIVOROS Y MARSUPIALES SILVESTRES EN EL NORESTE DE MEXICO

Existe poca información acerca del ciclo silvestre de Toxoplasma gondii en carnívoros y marsupiales silvestres en México. El objetivo de este estudio fue determinar la presencia de anticuerpos contra T. gondii en carnívoros y marsupiales silvestres en el noreste de México. La frecuencia de T. gondii en los especímenes capturados fue: margay (Leopardus wiedii; n=3; 33%), jaguarundi (Puma yagouaroundi; n=2; 0%), lince (Lynx rufus; n= 1; 100%), coatí (Nasua narica; n=7; 42%), coyote (Canis latrans; n=4; 25%), zorra gris (Urocyon cinereoargenteus; n=3; 66%), zorrillo (Conepatus leuconotus; n=1; 0%), y tlacuache (Didelphis sp.; n=5; 20%). Se comprueba la infección natural con T. gondii en carnívoros y marsupiales silvestres en el noreste de México.

EN PRENSA Solapamiento en los patrones de actividad de mamíferos y sus presas potenciales en un área de la Sierra Madre Occidental en Durango, México EN PRENSA

Las interacciones ecológicas son parte fundamental para el funcionamiento de los ecosistemas, por lo que indagar en éstas puede brindar información del equilibrio ecológico en un área. El objetivo de este estudio fue determinar las interacciones entre mamíferos y sus presas potenciales por medio del fototrampeo en el predio Sierra del Nayar, Durango. De agosto de 2016 a mayo de 2017 se colocaron cámaras trampa en la temporada de lluvias y secas. De los registros de las fotos se estimó el índice de abundancia relativa, los patrones de actividad por especie, y el índice de solapamiento depredador-presa o de competencia entre depredadores. Se registraron 13 especies de mamíferos y Meleagris gallopavo (guajolote silvestre). No hubo diferencias significativas intraespecíficas de los índices de abundancia relativa entre las temporadas de lluvias y secas para ninguna especie. Existen diferencias significativas interespecíficas de los índices de abundancia relativa durante el periodo de estudio, la temporada de lluvias y la de secas. Las especies más abundantes durante el periodo de estudio fueron: Odocoileus virginianus (venado cola blanca), M. gallopavo, Sciurus aberti (ardilla orejas peludas) y Canis latrans (coyote). Se estimó el índice de solapamiento de seis interacciones, de las cuales Urocyon cinereoargenteus (zorra gris)-Sylvilagus floridanus conejo del este y C. latrans-U. cinereoargenteus tuvieron el más alto índice de solapamiento y no presentaron diferencias significativas en sus patrones de actividad. Los patrones de actividad obtenidos concuerdan con lo reportado para las especies en Norteamérica.

Complete genome analysis confirms that the pygmy marmoset adenovirus is a variant of the skunk adenovirus 1 – Short communication

The complete genomic sequence along with phylogenetic analyses of an adenovirus (AdV), isolated from a dead captive pygmy marmoset (Callithrix pygmaea) from a Hungarian zoo is reported. Earlier, based on the phylogenetic analysis of the sequence of a PCR-amplified fragment from the DNA polymerase gene, the pygmy marmoset AdV (PMAdV) has been reported to cluster closest to certain chiropteran AdVs. In the following years similar AdVs were discovered in additional mammalian hosts, including a skunk (Mephitis mephitis), African pygmy hedgehogs (Atelerix albiventris), North American porcupines (Erethizon dorsatum) and grey fox (Urocyon cinereoargenteus). After the full genome analysis of the skunk adenovirus (SkAdV-1), a novel species Skunk mastadenovirus A (SkAdV-A) has been established. The AdVs, originating from the African pygmy hedgehogs, have been found to belong to virus species SkAdV-A. Partial gene sequences from the porcupine AdVs have also implied their very close genetic relatedness to SkAdV-A. The complete genomic sequence of PMAdV, examined in this study, was found to share 99.83% nucleotide identity with SkAdV-1, thus unequivocally represents a genomic variant of SkAdV-1. The observation that viruses classifiable as SkAdV-A are able to infect and cause diseases in several, distantly related mammals seems to deserve further studies to elucidate the infection biology of this intriguing AdV.

Relative abundance of coyotes influences gray fox occupancy across the eastern United States

Gray fox (Urocyon cinereoargenteus Schreber, 1775) populations in portions of the eastern United States have experienced declines whose trajectories differ from those of other mesocarnivore populations. One hypothesis is that gray fox declines may result from interspecific interactions, particularly competition with abundant coyotes (Canis latrans Say, 1823). Alternatively, gray foxes may respond negatively to increased urbanization and reduced forest cover. To evaluate these hypotheses, we used single-species occupancy models of camera trap data to test the effects of habitat covariates, such as the amount of urbanization and forest, on coyote and gray fox occupancy. Additionally, we test the effect of an n-mixture based index of the number of coyotes at each camera trap site on gray fox occupancy. Results indicate that occupancy probabilities of coyote and gray fox relate positively to the amount of forest, but they provided no evidence urban cover impacts gray foxes. Additionally, gray fox occupancy was negatively related to the index of the number of coyotes at each site. Our models support the idea that interactions with coyotes impact gray fox occupancy across the eastern U.S. These results illustrate how large scale studies can relate mechanisms identified within specific landscapes to phenomena observed at larger scales.