The truth about cats and dogs: Landscape composition and human occupation mediate the distribution and potential impact of non-native carnivores

The Law and the Pussycat: Public Perceptions of the Use of Municipal Bylaws to Control Free-Roaming Domestic Cats in Canada

Domestic cats (Felis catus) face contradictory public perceptions. In 2019, we examined public perceptions toward cats within the City of Prince George, British Columbia, Canada, using an online survey (1,464 responses) to assess perceptions toward free-roaming cats and the use of bylaws to address concerns. Perceptions were dependent on cat-ownership status; a majority of non-cat and former owners were concerned about free-roaming cats, current cat owners less so. There was considerable support for mandatory identification. Cat owners were not supportive of bylaws restricting free-roaming of cats, although this was supported by non-owners. Concerns include the negative impact on caring for a pet cat, and the fear that such bylaws would increase abandonment. Cat owners were not enthusiastic about fines for roaming cats, while non-cat owners were. There was considerable concern around including neutering cats as part of planned cat management. Our research also found nuanced concern for the impacts of management on impoverished owners, the welfare of cats and a recognition that it was the humans, rather than the cats, who should be the focus of active and thoughtful intervention.

Contribution of Home Gardens to Sustainable Development: Perspectives from A Supported Opinion Essay

Home gardening has a long history that started when humans became sedentary, being traditionally considered an accessible source of food and medicinal plants to treat common illnesses. With trends towards urbanization and industrialization, particularly in the post-World War II period, the importance of home gardens as important spaces for growing food and medicinal plants reduced and they began to be increasingly seen as decorative and leisure spaces. However, the growing awareness of the negative impacts of agricultural intensification and urbanization for human health, food quality, ecosystem resilience, and biodiversity conservation motivated the emergence of new approaches concerning home gardens. Societies began to question the potential of nearby green infrastructures to human wellbeing, food provisioning, and the conservation of traditional varieties, as well as providers of important services, such as ecological corridors for wild species and carbon sinks. In this context. and to foster adaptive and resilient social-ecological systems, our supported viewpoint intends to be more than an exhaustive set of perceptions, but a reflection of ideas about the important contribution of home gardens to sustainable development. We envision these humble spaces strengthening social and ecological components, by providing a set of diversified and intermingled goods and services for an increasingly urban population.

Dogs suppress a pivotal function in the food webs of sandy beaches

Domestic dogs are the most abundant carnivore globally and have demonstrable negative impacts to wildlife; yet, little evidence regarding their functional roles in natural food webs exists. Adding dogs to food webs may result in a net loss (via suppression of naturally occurring species), net gain (via mesopredator release), or no change (via functional replacement) to ecosystem function. Scavenging is a pivotal function in ecosystems, particularly those that are energetically supported by carrion. Dogs also scavenge on animal carcasses, but whether scavenging by dogs influences the structural and functional properties of food webs remains unclear. Here we used camera traps baited with carrion to test the effect of dogs on the composition and diversity of the vertebrate scavenger guild, as well as carrion detection and consumption rates. We conducted this work in sandy beach ecosystems, which rely on the import of marine organic matter (i.e. stranding of dead marine animals). Diversity of the scavenger community was similar on beaches without dogs. Dogs increased the time it took for carcasses to be detected and decreased the proportion of carrion consumed. This ‘dog suppression effect’ on scavenging was stronger for nocturnal mammalian scavengers, presumably being driven by indirect trait-mediated effects, which raises further questions about the broader ecological consequences of domestic dogs in natural systems.

Asymmetrical intraguild interactions with coyotes, red foxes, and domestic dogs may contribute to competitive exclusion of declining gray foxes

Species coexistence is governed by availability of resources and intraguild interactions including strategies to reduce ecological overlap. Gray foxes are dietary generalist mesopredators expected to benefit from anthropogenic disturbance, but populations have declined across the midwestern USA, including severe local extirpation rates coinciding with high coyote and domestic dog occurrence and low red fox occurrence. We used data from a large-scale camera trap survey in southern Illinois, USA to quantify intraguild spatial and temporal interactions among the canid guild including domestic dogs. We used a two-species co-occurrence model to make pairwise assessments of conditional occupancy and detection rates. We also estimated temporal activity overlap among species and fit a fixed-effects hierarchical community occupancy model with the four canid species. We partitioned the posterior distributions to compare gray fox occupancy probabilities conditional on estimated state of combinations of other species to assess support for hypothesized interactions. We found no evidence of broadscale avoidance among native canids and conclude that spatial and temporal segregation were limited by ubiquitous human disturbance. Mean guild richness was two canid species at a site and gray fox occupancy was greater when any combination of sympatric canids was also present, setting the stage for competitive exclusion over time. Domestic dogs may amplify competitive interactions by increasing canid guild size to the detriment of gray foxes. Our results suggest that while human activities can benefit some mesopredators, other species such as gray foxes may serve as bellwethers for habitat degradation with trophic downgrading and continued anthropogenic homogenization.

Mesocarnivore landscape use along a gradient of urban, rural, and forest cover

Mesocarnivores fill a vital role in ecosystems through effects on community health and structure. Anthropogenic-altered landscapes can benefit some species and adversely affect others. For some carnivores, prey availability increases with urbanization, but landscape use can be complicated by interactions among carnivores as well as differing human tolerance of some species. We used camera traps to survey along a gradient of urban, rural, and forest cover to quantify how carnivore landscape use varies among guild members and determine if a species was a human exploiter, adapter, or avoider. Our study was conducted in and around Corvallis, Oregon from April 2018 to February 2019 (11,914 trap nights) using 47 camera trap locations on a gradient from urban to rural. Our focal species were bobcat (Lynx rufus), coyote (Canis latrans), gray fox (Urocyon cinereoargenteus), opossum (Didelphis virginiana), raccoon (Procyon lotor), and striped skunk (Mephitis mephitis). Raccoon and opossum were human exploiters with low use of forest cover and positive association with urban and rural developed areas likely due to human-derived resources as well as some refugia from larger predators. Coyote and gray fox were human adapters with high use of natural habitats while the effects of urbanization ranged from weak to indiscernible. Bobcat and striped skunk appeared to be human avoiders with negative relationship with urban cover and higher landscape use of forest cover. We conducted a diel temporal activity analysis and found mostly nocturnal activity within the guild, but more diurnal activity by larger-bodied predators compared to the smaller species. Although these species coexist as a community in human-dominated landscapes throughout much of North America, the effects of urbanization were not equal across species. Our results, especially for gray fox and striped skunk, are counter to research in other regions, suggesting that mesopredator use of urbanized landscapes can vary depending on the environmental conditions of the study area and management actions are likely to be most effective when decisions are based on locally derived data.

The relationship between landscape features and domestic species on the occupancy of native mammals in urban forests

Landscape features such as roads, hiking trails, and forest edge are prevalent features of urban forests. These features can negatively influence biodiversity through fragmentation and facilitate the penetration of invasive species, particularly predators such as domestic dogs and cats. This study examined how these landscape features affect the distribution of native and domestic mammals and how domestic species affect the occupancy and activity patterns of native mammals. To this end, we conducted camera trap surveys in forested urban and suburban parks in Indiana and Kentucky, USA, to record the presence of native species (deer, raccoons, coyote, and opossums) and non-native predators (domesticated cats and dogs) in relation to distance to nearest roads, hiking trails, and forest edge. We found negative correlations between proximity to roads, hiking trails, and forest edge and the occupancy of the native species with this effect extending up to 300 m. We also found evidence that the presence of dog and cat was negatively correlated with the occupancy for all native species. We recommend park management consider the impact of roads, hiking trails, and forest edge when designing parks and the enforcement of dog leash regulations for the conservation of large mammals in urban parks.

Widespread Presence of Domestic Dogs on Sandy Beaches of Southern Chile

Dogs on sandy beaches are a threat to shorebirds. Managing this problem requires understanding the factors that influence the abundance of dogs in these ecosystems. We aimed to determine the proportion of beaches used by dogs and the effects of human presence on dog abundance on sandy beaches of southern Chile. We conducted dog counts and recorded the presence of tracks on 14 beaches. We used zero-inflated generalized linear mixed models to determine if the number of people, number of households, and other covariates were associated with dog abundance. We detected dog tracks on all the beaches, and dog sightings on most of them. Dogs were frequently not supervised (45%) and only 13% of them were leashed. The number of people on the beach and the number of houses near the beach were positively associated with the number of dogs on beaches. Finally, when dogs co-occurred with whimbrels (Numenius phaeopus), the probability of dog harassment was high (59%). Our work reveals that human presence determines the abundance of dogs on sandy beaches. Therefore, our study suggests that any strategy aiming at reducing dog harassment of shorebirds requires changes in those human behaviors that favor the presence of free-ranging dogs at beaches.

Identification of the population source of free-ranging cats threatening endemic species on Tokunoshima Island, Japan

Free-ranging cats Felis silvestris catus are harmful to endemic species, especially on islands. Effective management practices require an understanding of their habitat use and population source at the landscape level. We aimed to identify the source of the free-ranging cat population on Tokunoshima Island, Japan, which harbors a variety of endemic organisms as well as human settlements. Trapping data for the whole island were provided by local governments, and landscape factors (residential, agricultural, and woodlot areas and cattle barn density) affecting cat density were explored. An analysis of live-capture data indicated that the density (per 1 km2) of free-ranging cats was positively correlated with the densities of cattle barns and woodlot areas and negatively correlated with residential areas. An interview survey revealed that nearly half of the cattle barns feed free-ranging cats. The source habitat of free-ranging cats appears to be areas with a high density of cattle barns and a high percentage of woodlots in human-dominated landscapes. Feeding cats in cattle barns may strengthen the bottom-up process of population growth on the island. To reduce the impact of cats on endemic species on Tokunoshima Island, efforts to stop feeding cats in cattle barns are important. Reaching a consensus with stakeholders will require further studies of the ecological risks posed by free-ranging cats.

Projecting Mammal Distributions in Response to Future Alternative Landscapes in a Rapidly Transitioning Region

Finding balance between the needs of people and wildlife is an essential component of planning sustainable landscapes. Because mammals make up a diverse and ecologically important taxon with varying responses to human disturbance, we used representative mammal species to examine how alternative land-use policies might affect their habitats and distributions in the near future. We used wildlife detections from camera traps at 1591 locations along a large-scale urban to wild gradient in northern Virginia, to create occupancy models which determined land cover relationships and the drivers of contemporary mammal distributions. From the 15 species detected, we classified five representative species into two groups based on their responses to human development; sensitive species (American black bears and bobcats) and synanthropic species (red foxes, domestic cats, and white-tailed deer). We then used the habitat models for the representative species to predict their distributions under four future planning scenarios based on strategic versus reactive planning and high or low human population growth. The distributions of sensitive species did not shrink drastically under any scenario, whereas the distributions of synanthropic species increased in response to anthropogenic development, but the magnitude of the response varied based on the projected rate of human population growth. This is likely because most sensitive species are dependent on large, protected public lands in the region, and the majority of projected habitat losses should occur in non-protected private lands. These findings illustrate the importance of public protected lands in mitigating range loss due to land use changes, and the potential positive impact of strategic planning in further mitigating mammalian diversity loss in private lands.