North American Carnivores Research Articles

Trophic interactions between two sympatric mesocarnivores in an anthropized landscape from the Mexican highlands

The study of diets in North American carnivores has been assessed from different methods, essentially analyzing the composition of their diet, and classifying the species based on the breadth of their trophic niche. Still, studies that explore aspects of their interactions are limited. This work studies the predator-prey relationship through an interaction network analysis approach, nesting, and the analysis of core vs peripheral individuals, for two sympatric species of the Mexican highlands, the bobcat (Lynx rufus) and the coyote (Canis latrans). In addition, the effect on the structure of the interaction networks under two conditions of environmental disturbance was evaluated. In environments with high disturbance: A network was obtained for 46 bobcats and 18 coyotes, identifying six bobcats and five core coyotes; and in environments with low disturbance, the network was obtained for 134 bobcats and 38 coyotes, identifying 30 bobcats and eight core coyotes. Three of the analyzed networks presented a nested pattern with the WNOFD metric (High disturbance: L. rufus: Nesting = 0.51, p < 0.05, C. latrans: 4.13, p < 0.05; Low disturbance: L. rufus, 0.91, p < 0.05) and only one network with the NOFD metric was nested (Low disturbance = C. latrans, 19.51, p < 0.05). There was an effect of environmental disturbance on the evaluated networks; in highly disturbed environments, the structure and composition of the interactions are different for both species. Unlike conventional methods for studying the diet of carnivores, our results provide a different methodology that allows characterizing the network of trophic relationships between predators and their prey, evaluating whether their relationships are nested, and analyzing information at the level of individuals and sexes. In subsequent studies, it is relevant to investigate the fragility of the network due to the loss of essential components of its structure, which will allow establishing measures for its conservation. Also, presents for the first time the structure of the trophic interaction network for two sympatric mesocarnivores from the Mexican highlands, as a tool to study their relationships and show mechanisms of their coexistence.

Designing an assay to evaluate behavioral responses to opposite-sex conspecifics in the endangered black-footed ferret (Mustela nigripes).

The endangered black-footed ferret (ferret; Mustela nigripes) is a North American carnivore that is actively managed to reestablish self-sustaining wild populations. Behavioral abnormalities have been reported in the breeding program and may be a limiting factor for the species' success. Our goal was to design and test an assay that examines the ferret's exploratory response to odor cues in the form of soiled bedding from opposite-sex conspecifics. Across two breeding seasons, males and females were tested using a T-maze that connected their home nest box to two novel nest boxes containing two different conspecific's soiled bedding. For a control, we provided two clean bedding samples. We ran linear mixed models to determine the effect of sex, type of odor cue (soiled, clean), and order of trial (first, second) on time exploring and proportion of that time spent in each behavior. Ferrets spent the majority of time in the novel nest boxes sniffing (44%), standing alert (27%) and scratching (14%). Males explored for longer than females; however, both displayed similar behaviors. Type of cue influenced behavior, with ferrets sniffing more among soiled cues than clean cues. Habituation to the assay was also observed, with less exploration and more standing alert during the second trial of the day. This study is the first step in characterizing the ferret's exploratory response and provides information regarding vital investigatory and vigilance behaviors. The continual development of this assay to further evaluate reproductive and mate choice behaviors will facilitate more successful breeding of the species.

Genomic analyses of gray fox lineages suggest ancient divergence and secondary contact in the southern Great Plains.

The gray fox (Urocyon cinereoargenteus) lineage diverged from all other extant canids at their most basal node and is restricted to the Americas. Previous mitochondrial analysis from coastal populations identified deeply divergent (up to 1 Mya) eastern and western lineages that predate most intraspecific splits in carnivores. We conducted genotyping by sequencing and mitochondrial analysis on gray foxes sampled across North America to determine geographic concordance between nuclear and mitochondrial contact zones and divergence times. We also estimated the admixture within the contact zone between eastern and western gray foxes based on nuclear DNA. Both datasets confirmed that eastern and western lineages met in the southern Great Plains (i.e. Texas and Oklahoma), where they maintained high differentiation. Admixture was generally low, with the majority of admixed individuals carrying <10% ancestry from the other lineage. Divergence times confirmed a mid-Pleistocene split, similar to the mitochondrial estimates. Taken together, findings suggest gray fox lineages represent an ancient divergence event, far older than most intraspecific divergences in North American carnivores. Low admixture may reflect a relatively recent time since secondary contact (e.g. post-Pleistocene) or, alternatively, ecological or reproductive barriers between lineages. Though further research is needed to disentangle these factors, our genomic investigation suggests species-level divergence exists between eastern and western gray fox lineages.

A global indicator of utilized wildlife populations: Regional trends and the impact of management

A global indicator of utilized wildlife populations: Regional trends and the impact of management

Evaluating species-specific responses to camera-trap survey designs

Camera traps are widely used to collect information on the distribution and abundance of multiple species simultaneously. However, we still lack important guidance for designing camera-trap surveys to monitor multiple species, and the consequences of species-specific responses to survey design strategies are often overlooked. Using camera-trap data collected on ten medium-to-large North-American carnivores in northern Minnesota, USA, between 2016 and 2018 (23 337 active trap-days), we evaluated: 1) two different survey-design frameworks (random- versus road-based), 2) two different lure types (salmon oil versus fatty acid scent oil), 3) two different placement strategies (completely random versus randomly-selected sites with feature-based placement), 4) survey timing (spring versus fall) and 5) temporal trends in daily encounter probabilities. Using generalized linear mixed models, we found evidence of differential responses to all of these design strategies. For 9 out of 10 species, we found strong responses to survey design frameworks: red foxes Vulpes vulpes, coyotes Canis latrans, bobcats, Lynx rufus, striped skunks Mephitis mephitis, wolves C. lupus and gray foxes Urocyon cinereoargenteus, had estimated encounter frequencies that were 9- to 106-fold higher at unlured sites along secondary roads; black bears Ursus americanus, martens Martes americana and fishers Pekania pennanti had estimated encounter frequencies that were 15- to > 3600-fold higher at lured, randomly selected sites. For six species, salmon oil provided 2- to 4-fold more encounters than fatty acid scent oil, but feature-basedplacement only improved detections of fishers. Daily encounter probabilities differed between spring and fall for all species, and usually decreased slightly within each sampling period Our study confirms that even similar-sized or closely-related species respond differently to survey-design choices. To maximize encounter frequencies, we recommend that multi-species camera-trap studies use a mix of survey-design strategies and include these design features during statistical analysis.

Observations of American Badgers, Taxidea taxus (Schreber, 1777)&amp;nbsp;(Mammalia, Carnivora), in a restored tallgrass prairie in Illinois,&amp;nbsp;USA, with a new county record of successful reproduction

American Badgers, Taxidea taxus (Schreber, 1777) are poorly studied relative to other North American carnivores. We&amp;nbsp;report on observations of American Badgers within a restored tallgrass prairie ecosystem owned and managed by The&amp;nbsp;Nature Conservancy in Illinois. We documented badgers at six camera locations, including two prairie restorations restored&amp;nbsp;from row crop agriculture in 2002 and 2015. In addition, we confirmed breeding activity in Ogle County, filling&amp;nbsp;a gap in the known breeding distribution of American Badgers in Illinois. We provide context for these observations&amp;nbsp;and suggestions for future research.

Spatial variation in diet-microbe associations across populations of a generalist North American carnivore.

Generalist species, by definition, exhibit variation in niche attributes that promote survival in changing environments. Increasingly, phenotypes previously associated with a species, particularly those with wide or expanding ranges, are dissolving and compelling greater emphasis on population-level characteristics. In the present study, we assessed spatial variation in diet characteristics, gut microbiome and associations between these two ecological traits across populations of coyotes Canis latrans. We highlight the influence of the carnivore community in shaping these relationships, as the coyote varied from being an apex predator to a subordinate, mesopredator across sampled populations. We implemented a scat survey across three distinct coyote populations in Michigan, USA. We used carbon (δ13 C) and nitrogen (δ15 N) isotopic values to reflect consumption patterns and trophic level, respectively. Corresponding samples were also paired with 16S rRNA sequencing to describe the microbial community and correlate with isotopic values. Although consumption patterns were comparable, we found spatial variation in trophic level among coyote populations. Specifically, δ15 N was highest where coyotes were the apex predator and lowest where coyotes co-occurred with grey wolves Canis lupus. The gut microbial community exhibited marked spatial variation across populations with the lowest operational taxonomic units diversity found where coyotes occurred at their lowest trophic level. Bacteriodes and Fusobacterium dominated the microbiome and were positively correlated across all populations. We found no correlation between δ13 C and microbial community attributes. However, positive associations between δ15 N and specific microbial genera increased as coyotes ascended trophic levels. Coyotes provide a model for exploring implications of niche plasticity because they are a highly adaptable, wide-ranging omnivore. As coyotes continue to vary in trophic position and expand their geographic range, we might expect increased divergence within their microbial community, changes in physiology and alterations in behaviour.

Effects of land-use change and prey abundance on the body condition of an obligate carnivore at the wildland-urban interface

Land-use change represents a primary driver of carnivore population declines, yet some large carnivore species have acclimated and persist within anthropogenically altered landscapes. Previous attention has been focused on the genetic and behavioral implications of land-use changes, but few studies have investigated how human development impacts animal physiology and health. Here we examined how body condition scores of a widely distributed North American carnivore, the puma (Puma concolor), are affected by anthropogenic habitat modification. For this study we collected 252 puma camera trap events across a land-use gradient in the San Francisco Bay Area. We found that pumas in this region generally had body condition scores within a healthy range. However, pumas in areas with marginal development (e.g., parks, golf courses, low-density residences) had significantly higher body condition scores than conspecifics in areas defined as highly developed (urban) or undeveloped (wilderness). Notably, detections of black-tailed deer (Odocoileus hemionus columbianus) showed the same patterns. Additionally, puma body condition was significantly and positively correlated with detection frequency of small prey like raccoons and squirrels. Taken together, our findings show that pumas are present in developed environments, and suggest that puma body condition may reflect relative prey abundance across land-use types. We suggest that in mixed-use landscapes where public tolerance of large carnivores is sufficient, management efforts should integrate non-wilderness lands into conservation plans for pumas. However, in areas defined by low tolerance or high conflict potential, management should focus on public education and control of food resources that attract pumas to those areas.

First detection of Trichinella pseudospiralis infection in raccoon (Procyon lotor) in Central Europe

The raccoon (Procyon lotor) is a North American carnivore introduced to Europe in the 20th Century. Raccoons are believed to be the potential hosts of many parasites, or to be involved in their transmission to other animals. Nematodes of the genus Trichinella can infect many carnivorous and omnivorous animals worldwide. The aim of the present study was to determine the occurrence of Trichinella spp. infection in raccoons in Central Europe. Muscle samples were collected from various regions of Poland, the Czech Republic and Germany during the years 2012–2016. The larvae of Trichinella spp. were detected in 11 raccoons, and these were identified as T. spiralis and T. pseudospiralis by multiplex PCR (89.9% and 9.1%, respectively). No mixed infection was observed. This is the first report describing the occurrence of T. spiralis and T. pseudospiralis in P. lotor in Central Europe. Our findings also show that the raccoon population acts as a reservoir of Trichinella pseudospiralis.

Species loss on spatial patterns and composition of zoonotic parasites.

Species loss can result in the subsequent loss of affiliate species. Though largely ignored to date, these coextinctions can pose threats to human health by altering the composition, quantity and distribution of zoonotic parasites. We simulated host extinctions from more than 1300 host-parasite associations for 29 North American carnivores to investigate changes in parasite composition and species richness. We also explored the geography of zoonotic parasite richness under three carnivore composition scenarios and examined corresponding levels of human exposure. We found that changes in parasite assemblages differed among parasite groups. Because viruses tend to be generalists, the proportion of parasites that are viruses increased as more carnivores went extinct. Coextinction of carnivore parasites is unlikely to be common, given that few specialist parasites exploit hosts of conservation concern. However, local extirpations of widespread carnivore hosts can reduce overall zoonotic richness and shift distributions of parasite-rich areas. How biodiversity influences disease risks remains the subject of debate. Our results make clear that hosts vary in their contribution to human health risks. As a consequence, so too does the loss (or gain) of particular hosts. Anticipating changes in host composition in future environments may help inform parasite conservation and disease mitigation efforts.

Historical biogeography of theIsthmus ofPanama

About 3 million years ago (Ma), the Isthmus of Panama joined the Americas, forming a land bridge over which inhabitants of each America invaded the other-the Great American Biotic Interchange. These invasions transformed land ecosystems in South and Middle America. Humans invading from Asia over 12000 years ago killed most mammals over 44 kg, again transforming tropical American ecosystems. As a sea barrier, the isthmus induced divergent environmental change off its two coasts-creating contrasting ecosystems through differential extinction and diversification. Approximately 65 Ma invading marsupials and ungulates of North American ancestry, and xenarthrans of uncertain provenance replaced nearly all South America's non-volant mammals. There is no geological evidence for a land bridge at that time. Together with rodents and primates crossing from Africa 42 to 30 Ma, South America's mammals evolved in isolation until the interchange's first heralds less than 10 Ma. Its carnivores were ineffective marsupials. Meanwhile, North America was invaded by more competitive Eurasian mammals. The Americas had comparable expanses of tropical forest 55 Ma; later, climate change confined North American tropical forest to a far smaller area. When the isthmus formed, North American carnivores replaced their marsupial counterparts. Although invaders crossed in both directions, North American mammals spread widely, diversified greatly, and steadily replaced South American open-country counterparts, unused to effective predators. Invading South American mammals were less successful. South America's birds, bats, and smaller rainforest mammals, equally isolated, mostly survived invasion. Its vegetation, enriched by many overseas invaders, remained intact. This vegetation resists herbivory effectively. When climate permitted, South America's rainforest, with its bats, birds and mammals, spread to Mexico. Present-day tropical American vegetation is largely zoned by trade-offs between exploiting well-watered settings versus surviving droughts, exploiting fertile versus coping with poor soil, and exploiting lowland warmth versus coping with cooler altitudes. At the start of the Miocene, a common marine biota extended from Trinidad to Ecuador and western Mexico, which evolved in isolation from the Indo-Pacific until the Pleistocene. The seaway between the Americas began shoaling over 12 Ma. About 10 Ma the land bridge was briefly near-complete, allowing some interchange of land mammals between the continents. By 7 Ma, the rising sill had split deeper-water populations. Sea temperature, salinity and sedimentary carbon content had begun to increase in the Southern Caribbean, but not the Pacific. By 4 Ma, the seaway's narrowing began to extinguish Caribbean upwellings. By 2 Ma, upwellings remained only along Venezuela; Caribbean plankton, suspension-feeding molluscs and their predators had declined sharply, largely replaced by bottom-dwelling corals and calcareous algae and magnificent coral reefs. Closing the seaway extinguished the Eastern Pacific's reef corals (successors recolonized from the Indo-Pacific 6000 years ago), whereas many molluscs of productive waters that once thrived in the Caribbean now survive only in the Eastern Pacific. The present-day productive Eastern Pacific, with few, small coral reefs and a plankton-based ecosystem contrasts with the Caribbean, whose clear water favours expansive coral reefs and bottom-dwelling primary producers. These ecosystems reflect the trade-off between fast growth and effective defence with attendant longevity. Overfishing with new technologies during the last few centuries, however, has caused population crashes of ever-smaller marine animals, devastating Caribbean ecosystems.

Molecular techniques for identifying intraguild predators of fishers and other north American small carnivores

Identifying predators of threatened and endangered species is important for understanding and reducing the impacts of predation. Visible evidence collected from a carcass alone is often insufficient to accurately identify predator species. The DNA from the predator left on the carcass allows for a definitive identification of predator species associated with the carcass, but DNA can be difficult to isolate independently from the prey. We developed field collection and molecular protocols for amplifying canid and felid predator DNA from saliva on fisher (Martes pennanti) carcasses without amplifying fisher DNA itself. We tested the protocol on fisher carcasses suspected of having been killed by a bobcat (Lynx rufus), mountain lion (Puma concolor), coyote (Canis latrans), and domestic dog. We successfully amplified and sequenced DNA from these 4 predator species, confirming predation by them on fishers. We confirmed that these protocols could also identify other felid and canid predators of several other small North American carnivores. © 2013 The Wildlife Society.

De factorefugia, ecological traps and the biogeography of anthropogenic cougar mortality in Utah

Aim Modern extirpations within the Carnivora have generally followed the human footprint. The contagion hypothesis predicts that range contractions should occur along gradients in human activity, leaving relict populations in remote areas at range edges. We evaluated this hypothesis for cougars (Puma concolor), a widely distributed and heavily exploited North American carnivore. Location Colorado Plateau and Great Basin ecoregions within Utah, USA. Methods We examined the spatial distribution of anthropogenic cougar mortality (n = 4217) using indices of remoteness and habitat quality within a GIS/multiple-regression analytical framework. To identify areas of disproportionately high or low exploitation rates, we used break-points from the literature and local field studies. We defined de facto refugia as watersheds with mean annual harvest rates ≤ 24% of the predicted population, whereas ecological traps were those watersheds that exceeded this value. Results Cougar harvest rates were greater in the core and lower along the periphery of their statewide geographic range. The largest refugia were overrepresented in arid ecoregions with low human population densities, whereas ecological traps were concentrated in areas of low remoteness. Ecological traps were within mean cougar dispersal distances from refugia, highlighting the potential for source-sink dynamics. Patterns of anthropogenic cougar mortality generally followed the predictions of the contagion hypothesis, being spatially correlated with human access in high-quality habitats. Main conclusions Low-quality habitats on the range margins are likely to harbour carnivore populations in the event of widespread human-caused declines, and therefore may have greater conservation value than has previously been assumed. Resource managers may consider using the distribution of de facto refugia and ecological traps within a source-sink context to develop conservation strategies for cougars and other wide-ranging, low-density carnivores with high dispersal tendencies.

Using host associations to predict spatial patterns in the species richness of the parasites of North American carnivores

Despite the central theme in ecology of evaluating determinants of species richness, little effort has been focused on parasites. Here, we developed a parasite diversity model based on known host associations with 29 North American carnivores to investigate the spatial heterogeneity of parasite richness, its relationship to carnivore richness, and how host composition and specificity influenced these patterns. Patterns in parasite species richness closely tracked carnivore species richness across space and this relationship was robust to deviations from the assumption that parasites match the distribution of their hosts. Because wide-ranging hosts disproportionately contributed to total and specialist parasite species richness, conservation programmes that focus on these common hosts may capture not only much of biological diversity, but also unwittingly sources of human diseases. We supply the first parasite diversity model to understand broad-scale patterns in species richness patterns for North American carnivores, which can inform both future parasite conservation and disease management.

The Rise of the Mesopredator

Apex predators have experienced catastrophic declines throughout the world as a result of human persecution and habitat loss. These collapses in top predator populations are commonly associated with dramatic increases in the abundance of smaller predators. Known as “mesopredator release,” this trophic interaction has been recorded across a range of communities and ecosystems. Mesopredator outbreaks often lead to declining prey populations, sometimes destabilizing communities and driving local extinctions. We present an overview of mesopredator release and illustrate how its underlying concepts can be used to improve predator management in an increasingly fragmented world. We also examine shifts in North American carnivore ranges during the past 200 years and show that 60% of mesopredator ranges have expanded, whereas all apex predator ranges have contracted. The need to understand how best to predict and manage mesopredator release is urgent—mesopredator outbreaks are causing high ecological, economic, an...

Characterization of a western North American carnivore community using PCR–RFLP of cytochrome b obtained from fecal samples

We developed a simple and reliable method to identify carnivore scats to species using PCR and RFLP of a portion of the mtDNA cytochrome b gene, which works for seven of the most common carnivores in western North America. We identified a short (196 bp) polymorphic region of cytochrome b which would be easily amplifiable even from degraded DNA, developed a primer set, and isolated a set of three restriction enzymes (HpaII, DdeI, HpyCH4V) that would identify the seven target species. In order to test whether this protocol would effectively iden- tify scats obtained in the field we collected 243 carnivore scats from 12 sites in the San Francisco Bay area. Eighty five percent (206) of our samples successfully amplified and were subsequently identified to species using our RFLP protocol. We selected 108 of these samples to sequence; our species identifications based on sequencing were identical to those obtained using our PCR-RFLP method. Our PCR-RFLP method is a simple and efficient means to identify carnivore scats to species, eliminating the need for sequencing, which is costly and requires more laboratory equipment. The technique can also be modified depending on the species present at a particular site. It allows for rapid and noninvasive assessment of multiple carnivore taxa and is particularly useful for surveying populations across many sites.

DifferentiatingDracunculusmedinensisfromD.insignis, by the sequence analysis of the 18S rRNA gene

This study, undertaken as a component of the global Dracunculiasis Eradication Program (DEP), was designed to provide molecular tools to distinguish Dracunculus medinensis, the nematode causing human dracunculiasis, from other tissue-dwelling nematodes, including other Dracunculus species that infect humans and other animals. DNA was extracted from D. medinensis and from a closely related species that infects North American carnivores, D. insignis, so that the genes coding for the small-subunit ribosomal RNA (18S rRNA) of the parasites could be amplified, sequenced and compared. Sequences were obtained for 20 specimens of D. medinensis (from humans in Pakistan, Yemen and six African countries endemic for dracunculiasis) and three of D. insignis (from raccoons trapped in the state of Georgia in the southern U.S.A.). All of the D. medinensis 18S-rRNA sequences were found to be 1819 bases long and identical. The three D. insignis 18S-rRNA sequences were also found to be identical to each other but were 1821 bases long and differed from the D. medinensis 18S- rRNA sequence at eight positions (representing a difference of 0.44%). The 18S-rRNA coding region of a Guinea worm extracted from a dog in Ghana was indistinguishable from that of the D. medinensis isolates from human cases. These results provide the basis for the molecular differentiation of D. medinensis that will permit the DEP to determine, rapidly and accurately, whether a worm recovered from an area considered dracunculiasis-free is a specimen of D. medinensis or not.

Range Contractions of North American Carnivores and Ungulates

We compared the historic and current geographical ranges of 43 North American carnivores and ungulates to identify large-scale patterns in range contractions and expansions. Seventeen of the species had experienced range contractions over more than 20% of their historic range. In areas of higher human influence, species were more likely to contract and less likely to persist. Species richness had also declined considerably since historic times. The temperate grasslands and temperate broadleaf‐mixed forest biomes lost the highest average number of species, while the boreal forest and tundra showed fewer numbers of species lost. Species contractions were a result of Euro-American settlement and postsettlement development in North America. These effects have been widespread and indicate a rapid collapse of species distributions over the course of only 1 to 2 centuries. The results of this study can be used to improve scientists’ knowledge of historical reference conditions and to provide input for wildlife reintroductions and for the creation of wildlife reserves.

EVOLUTION OF INDUCED OVULATION IN NORTH AMERICAN CARNIVORES

We tested the hypothesis that induced ovulation is adaptive in North American carnivores by providing a mechanism to overcome the risk of unsuccessful mating in solitary species living in seasonal environments and a method for females to evaluate male quality via sexual selection inside the reproductive tract. We obtained published data on North American carnivores and determined from their distribution a coefficient of seasonality and primary productivity. Using traditional statistics and comparative methods, we determined that induced ovulators lived in more seasonal environments apparently not influenced by energy. No statistical differences in behavioral traits existed between induced and noninduced ovulators, but trends in data were consistent with our predictions, with induced ovulators tending to have larger home ranges and longer estrous periods. Mating systems also differed between the groups: induced ovulators were characterized by mostly (93%) multimale mating systems, whereas noninduced ovulators were monogamous (42%), multimale (33%), or polygynous (25%). Also, induced ovulators exhibited larger sexual dimorphism and smaller neonates than noninduced ovulators or felids. We suggest that induced ovulation evolved through sexual selection as a reproductive strategy beneficial for males (assurance of egg fertilization during short pair bonds) and females (postcopulatory mate choice based on level of stimulation causing induced ovulation).

On the evolution of the mammalian baculum: vaginal friction, prolonged intromission or induced ovulation?

ABSTRACTThe function of the mammalian baculum is a puzzling enigma in mammalian morphology. Three hypotheses for the evolution and persistence of the mammalian baculum have been proposed: the vaginal friction hypothesis; the prolonged intromission hypothesis; and the induced ovulation hypothesis. We tested these three hypotheses using phylogenetically corrected methods and data on North American carnivores. Baculum length was independent of sexual dimorphism and duration of copulation, thus refuting the vaginal friction and prolonged intromission hypotheses, respectively. Also, baculum length did not differ between induced ovulators and simultaneous ovulators, thus also refuting the induced ovulation hypothesis. We suggest that other aspects of carnivore life history, such as mating systems, may help explain the evolution of the mammalian baculum.