"Over the past two years, citizens of Raleigh, North Carolina and Washington D.C. have set up camera traps on their properties to assist in research by the North Carolina Museum of Natural Sciences and North Carolina State that evaluated to what extent non-connected patches of green space allows less urban‐adapted species to occupy urban/suburban/exurban areas, simultaneously evaluating to what extent conflict/tolerance occurs between species in these constricted regions............."Results determined that a lot of animal activity occurred in the suburbss concentrated in the remaining green space".........."As a rule, carnivores try to avoid people, so they are moving through the strips of remaining forest, where they are more likely to interact with each other"............"In general, the smaller carnivores steer clear of the larger ones".............. "Some have theorized that smaller carnivores might stay closer to people, using them as human shields from larger predators".........."But that wasn't borne out by the study"............."On the contrary, gray foxes and coyotes especially—the smallest and largest respectively—actually tended to use the same sites".............. "In other words, they didn't avoid each other, which was pretty surprising"...............""Although coyotes seem to prefer rural areas, they seem(as most of us know) to be infiltrating more populated regions in suburban areas in Raleigh and Washington, D.C."..........."The really surprising find was bobcats utilizing suburban Durham, North Carolina, and to a lesser extent, Raleigh".............""And in Washington, D.C., there were some black bears, not in suburban areas, but in the exurban region – between suburban and rural in terms of housing density"..........."Eastern forest habitat fragmentation is concentrating the larger, less urban‐adapted carnivores (i.e. bobcats, coyotes) into limited green space, leading to more spatial interactions with urban‐adapted species (i.e. grey and red foxes)"............."Grey foxes were the one species that interacted significantly with every other species existing in the D.C./Raleigh quadrant, interacting negatively with both red foxes and bobcats and positively with coyotes"..........."The negative interaction between grey foxes and red foxes and bobcats respectively occurred across all levels of urbanization and forest fragmentation"............"The diets of both fox species overlap significantly but grey foxes tend more towards omnivory eating habits and have been reported to exclude red foxes from some habitats".......... "Both fox species used suburban yards extensively in this study"......... "Red foxes in particular have been recorded in European cities since the 1930s, doing the same in North American cities over the last 20 years"............"Grey fox diet tends to overlap less with bobcats than with red foxes but they (gray foxes) are subject to intraguild predation by the larger bobcat"............."This may account for the negative spatial interaction the study revealed"............."Grey foxes and coyotes appear to require woodlots to navigate suburban areas and share these spaces without obvious negative consequences, even where those woodlots are rare"..........."Grey foxes are excellent tree climbers(red foxes cannot climb), giving them the ability to avoid direct persecution from coyotes which likely facilitates coexistence between the two canids"............ "By contrast, red foxes and bobcats, the most and least urban‐adapted species respectively, appear to spatially avoid one another in areas where large tracts of green space are particularly sparse"........... "Where green space is adequate, there appears to be sufficient opportunity for coexistence in an urban landscape between these two species"..........."Large carnivores typically avoid humans, and smaller carnivores(in other research studies) have been shown to reduce potenially deadly encounters with larger carnivores by living closer to people, a hypothesis known as the “human shield effect”..............."However, this most recent D.C./Raleigh research found no clear positive association between the smaller carnivores (foxes) and housing density, nor did they appear to spatially avoid some larger carnivores (coyotes) at higher housing densities as would be expected if they were using humans as shields"............."On the contrary, there was no evidence of a significant interaction between red foxes and coyotes, and grey foxes and coyotes at high housing density, suggesting that human‐dominated areas do not act as spatial refugia for foxes in these cities".............."A recent study of urban parks in Cleveland, OH, USA found much stronger evidence of a human shield effect between coyotes and red foxes, noting opposing responses to human development of red foxes and coyotes and avoidance of coyotes by red foxes, supporting the idea that red foxes use humans as shields".......... For all species evaluated, the amount of remaining forest patches was the most important determinant of occupancy"........... As both D.C. and Raleigh have significant forest patches, less urban‐adapted carnivores are able to successfully use this forest cover to navigate successfully along the urbanization gradient and exploit the rich food and cover resources suburban areas have to offer"

https://phys.org/news/2019-04-multiple-carnivores-coexist-cities.html

APRIL 16, 2019

Can multiple carnivores coexist in cities?

by North Carolina State University

Coyote near home in Raleigh, North Carolina

As growth makes neighborhoods more crowded for humans, it's also concentrating carnivores like bobcats and coyotes into the remaining green spaces, leading them to interact with each other more frequently than they do in wild areas, according to research in Raleigh, North Carolina, and Washington, D.C.

 Gray Fox

The citizen science study looks at how carnivores interact with each other when they're sharing space in small suburban forest patches. With the help of 557 volunteers and 1,260 remote cameras set up in suburban, exurban, rural and wild areas, the researchers documented 6,413 carnivores among nearly 43,000 images of wildlife. Carnivore species included bobcats and coyotes along with smaller gray and red foxes.

Camera locations in Washington, DC and Raleigh, NC, USA from 2012 to 2016. The gradient from wild to urban is defined as the average number of houses in a 1 km radius (Wild = ≤0.5, Rural = 0.51–12.63, Exurban = 12.63–147.05, Suburban = 147.06–1,000, Urban > 1,000). Examples of the three plot types sampled in each city (residential yard, small forest and large forest) are pictured using satellite imagery

"We found a lot of animal activity in the suburbs, but it was really concentrated in the remaining green space. We think carnivores are trying to avoid people, so they are moving through the strips of remaining forest, where they are more likely to interact with each other," says lead author Arielle Parsons, researcher with the North Carolina Museum of Natural Sciences and Ph.D. student at North Carolina State University.

Red Fox

"What we discovered was that preserving green space in our cities is important not only for humans but also for wildlife species. Green space provides cover, it provides food and it's a good way for carnivores to navigate without being in any danger from people."

Occupancy for coyote and grey fox in the presence and absence of each other conditional on the absence of bobcat and red fox along a housing density gradient in low (5%–50% in a 5 km radius) and high per cent local forest (51%–100% in a 100 m radius). Data were taken from camera traps run in Washington, DC (a) and Raleigh, NC, USA (b) between 2012 and 2016. Lines show posterior means and shaded regions are 95% credible intervals. In both cities, coyote and grey fox occupancy was higher in low forest at high housing density when in the presence of the other species 

In general, the smaller carnivores steer clear of the larger ones. Some have theorized that smaller carnivores might stay closer to people, using them as "human shields" from larger predators. But that wasn't borne out by the study.

"We found, on the contrary, that gray foxes and coyotes especially—our smallest species and our largest species—actually tended to use the same sites," Parsons says. "In other words, they didn't avoid each other, which was pretty surprising."

Black Bear

For those who are wary about having carnivores in their midst, Parsons says it's actually a good thing, given the key role they play in the ecosystem.

"Our study is showing that carnivores are trying to stay away from people by using forested areas," Parsons says. "If we give them the opportunity to do that through preservation of green space and green space corridors through our urban areas, carnivores are going to continue to live nearby, which is actually a good thing for the ecology of our cities."

"Just like roadways and sidewalks focus human movement and increase the potential for interaction, we find the high use of strips of remaining green space by carnivores increases their level of interaction," says study co-author Roland Kays, a zoologist with NC State and the N.C. Museum of Natural Sciences. "This shows how urban planning can affect the ecology of animals that share cities with people."

More information: Arielle W. Parsons et al, Urbanization focuses carnivore activity in remaining natural habitats, increasing species interactions, Journal of Applied Ecology (2019). DOI: 10.1111/1365-2664.13385

Journal information: Journal of Applied Ecology