What Does the Fox Need?

A red fox prowls the urban greenbelt in Boise, Idaho. Photo: Phares Book

A red fox prowls the urban greenbelt in Boise, Idaho. Photo: Phares Book

By now, we all know what the fox says. But what about what the fox needs?

Have you ever seen a fox in an urban area and wondered how it survives? Or why there are foxes in some parts of the city and not others?

Scientists have asked the same questions about many urban-dwelling animals. Here’s what they found with three surprisingly adaptable urban-dwelling mammals: the fox, the coyote, and the bobcat.

Background

Foxes, coyotes, and bobcats are all medium sized predators sometimes known as mesopredators.

I chose these animals because they can be found in cities throughout the United States. They will be familiar to most of our readers, yet they aren’t frequently seen.

I found studies about three species of urban foxes: red fox, Vulpes vulpes; gray fox, Urocyon cinereoargenteus; and kit fox, Vulpes macrotis. I will draw on information from all of these studies when talking about foxes, but keep in mind that there may be variation between species.

Food

What does the coyote need? Photo: Matt Miller/TNC

What does the coyote need? Photo: Matt Miller/TNC

A smorgasbord of food options is available in cities: garbage, garden food, rodents, birds, pets, road-kill, and food that people leave out – even pet food (Bateman 2012).

Foxes, coyotes, and bobcats are all predators, but they have different eating habits, especially when they live in cities.

Red foxes can get up to 60% of their diet from human sources and one study found remains of human food or food packaging in 62% of red fox scat (i.e. poo) in Orange County, CA. They also eat a number of the rodents and birds that are commonly found in cities (Bateman 2012).

Kit foxes and red foxes have been observed eating the food left at cat feeding stations in Bakersfield, CA (Harrison 2011).

Coyotes in the city take advantage of some human-sourced food (only about 2 to 11% of their diet), but get most of their calories from hunting and foraging. Their primary foods are rodents, rabbits, deer, and vegetation (Gese 2012).

Some of this “natural” diet can be from road-kill deer carcasses (Bateman 2012).

If you didn’t already have enough reason to keep your cat indoors: up to 13% of an urban coyote’s diet may consist of cats (Bateman 2012).

Fruit was found in 23% of Chicago coyote scats and 43% of urban Washington state coyote scats (Bateman 2012).

Bobcats are pure carnivores: meat is always what’s for dinner. They rely on hunting to obtain food (Bateman 2012, Fischer 2012, Ordeñana 2010, Ruell 2012).

In wild areas they are opportunistic hunters, eating a wide variety of mammals (from mice to deer), reptiles, birds, fish, insects, and eggs (Rubin 2006). Many of these foods, notably birds, rodents and insects, are also available in cities.

 

A bobcat in the suburbs. Photo by Dennis Larson via a Creative Commons license.

A bobcat in the suburbs. Photo by Dennis Larson through a Creative Commons license.

Cover

In order to establish a sustainable population, urban mammals need a safe place to breed, rest, and raise their young.

Urban red foxes have been recorded breeding under the floorboards of occupied houses and derelict buildings in the UK (Bateman 2012) – and it is likely that sometimes they do the same in the US.

Small culverts, thickets, and wooded areas provide needed resting areas for foxes (Bateman 2012).

They prefer to raise their young (kits, pups, or cubs) in dens. They might dig these dens, for which they need an area with soil that is soft enough to dig in (Bateman 2012).

Kit foxes can dig their own dens, but some take over abandoned dens – or even share them with skunks! (Harrison 2011).

Coyotes prefer riparian areas and patches of native grass (manicured lawns don’t count!) to rest and breed (Gese 2012).

They will not use human buildings for shelter, but like foxes, they dig their dens (Bateman 2012). Wooded areas are preferred for denning; one study found 15 of 19 den sites in wooded areas (Gese 2012).

Bobcats typically only take up residence in very large habitat fragments within cities or make forays into cities while still residing in wild areas (Bateman 2012, Chupp, 2013, Crooks 2002, Lowry 2013, Ordeñana 2013, Tigas 2003).

They likely inhabit dens within these areas that are similar to their dens in wild areas (in rock formations, hollow logs, etc.) and venture into the city to hunt.

Space

Even in the city, the mesopredators need space to forage with corridors that connect enough habitat patches or other food sources that they can survive.

Studies on how much space foxes, coyotes, and bobcats need and how far into a city that space can be have had varied results.

Most studies have found that foxes are the most adapted to living deep within urban areas, within the smallest most fragmented patches (Chupp 2013, Crooks 2002, Tigas 2003).

These studies argue that the areas inhabited by foxes are too small to support larger carnivores like coyotes and bobcats, but that the foxes thrive because they are “released” from predation by those larger mammals.

Surprisingly, one study in southern California found coyotes and bobcats at least visiting – if not dwelling in – isolated patches in the interior of cities while foxes were relegated to the outskirts (Ordeñana 2010).

This study posits that perhaps the foxes have moved out to avoid being eaten by the larger predators.

The smallest area recorded as a gray fox habitat (whether urban or rural) was .97 km2 (Rubin 2006).

Foxes in cities have smaller territories than rural foxes, because their food resources are higher and more stable (Bateman 2012, Gosselink 2010).

The smallest area recorded as coyote habitat (whether urban or rural) was 2.1 km2 for a female and 2.7 km2 for a male (Rubin 2006).

Coyotes in Chicago were found to have territories on average roughly twice those of rural coyotes. However, the smallest studied was 1.0 km2 – smaller than those recorded in Rubin (Gese 2012).

Gese theorizes that it takes a larger area of city habitat to meet a coyote’s feeding needs (2012). This is probably because they still hunt for most of their food, unlike the foxes above that take advantage of human-sourced food.

The smallest area recorded as a bobcat habitat (whether urban or rural) was 1.0 km2 for a female & 2.6 km2 for a male (Rubin 2006).

Urban bobcats typically have larger range sizes than their urban counterparts. This may be because they are traveling into the city to feed and then back out to dens (Lowry 2013).

All of these urban mammals use places like flood channels, drainage lines, power line corridors, beach strands, and railroad corridors to get from one place to another in the city (Bateman 2012).

They typically travel at night to avoid humans (Gese 2012 – of coyotes, Lowry 2013 – of coyotes & bobcats).

Coyote crosses the road. Photo by Oregon Department of Fish & Wildlife through a Creative Commons license.

Coyote crosses the road. Photo by Oregon Department of Fish & Wildlife through a Creative Commons license.

How to Live Near Urban Carnivores

Be sure to treat urban carnivores with a healthy respect. It is not safe for predators or for people to get too comfortable around one another.

Most of these mammals, even when living in cities, are naturally shy and are unlikely to approach you (Crooks 2002). However, some coyotes in Arizona have been known to approach humans, especially people who are walking dogs (Lawrence 2011).

If you see a coyote that seems to be following you, the appropriate response is to harass it. Do not hurt it, but do something to let it know that it should keep its distance from humans.

This is not only for your safety (and your pet’s) but also for the safety of the animal itself.

Keep your cats indoors or walk them on a leash.

Nature Conservancy Scientist and urban wildlife specialist John S. C. Herron says: “Domestic cats compete with urban predators – cats that are allowed outdoors are predators too, and since they’re fed by people, cat numbers don’t go down when prey numbers go down – so when prey isn’t abundant, it’s our wild predators who suffer.”

And as tempting as it may be, it is also best not to intentionally feed wild mammals. Gathering together for food can facilitate the spread of diseases.

Opinions expressed on Cool Green Science and in any corresponding comments are the personal opinions of the original authors and do not necessarily reflect the views of The Nature Conservancy.

References

Bateman, P. W. and P. A. Fleming. 2012. Big city life: carnivores in urban environments. Journal of Zoology 287:1-23.

Bozarth, C. A., F. Hailer, L. L. Rockwood, et al. 2011. Coyote colonization of northern Virginia and admixture with Great Lakes wolves. Journal of Mammalogy 92(5):1070-1080.

Chupp, A. D., A. M. Roder, L. L. Battaglia, et al. 2013. A case study of urban and peri-urban mammal communities: implications for the management of National Park Service areas. Northeastern Naturalist 20(4):631-654.

Crooks, K. R. 2002. Relative sensitivities of mammalian carnivores to habitat fragmentation. Conservation Biology 16(2):488-502.

Fischer, J. D., S. H. Cleeton, T. P. Lyons, et al. 2012. Urbanization and the predation paradox: the role of trophic dynamics in structuring vertebrate communities. Bioscience 62(9):809-818.

Gese, E. M., P. S. Morey, and S. D. Gehrt. 2012. Influence of the urban matrix on space use of coyotes in the Chicago metropolitan area. Journal of Ethology 30:413-425.

Gosselink, T. E., K. A. Piccolo, T. R. Van Deelen, et al. 2010. Natal dispersal and philopatry of red foxes in urban and agricultural areas of Illinois. Journal of Wildlife Management 74(6):1204-1217.

Harrison, S. W. R., B. L. Cypher, S. Bremmer-Harrison, et al. 2011. Resource use overlap between urban carnivores: implications for endangered San Joaquin kit foxes (Vulpes macrotis mutica). Urban Ecosystems 14:303-311.

Lawrence, S. E. and P. R. Krausman. 2011. Reactions of the public to urban coyotes (Canis latrans). Southwestern Naturalist 56(3):404-409.

Lowry, H., A. Lill, and B. B. M. Wong. 2013. Behavioural responses of wildlife to urban environments. Biological Reviews 88:537-549.

Ordeñana, M. A., K. R. Crooks, E. E. Boydston, et al. 2010. Effects of urbanization on carnivore species distribution and richness. Journal of Mammalogy 91(6):1322-1331.

Rubin, E. S., H. L. Rustigian, and M. D. White. 2006. Green Visions Plan for 21st Century Southern California: A Guide for Habitat Conservation, Watershed Health, and Recreational Open Space. 13. Target Species Habitat Mapping, University of Southern California GIS Research Laboratory and Center for Sustainable Cities, Los Angeles, California.

Ruell, E. W., S. P. D. Riley, M. F. Antolin, et al. 2012. Urban habitat fragmentation and genetic population structure of bobcats in coastal southern California. The American Midland Naturalist 168(2):265-280.

Tigas, L. A., D. H. Van Vuren, and R. M. Sauvajot. 2003. Carnivore persistence in fragmented habitats in urban southern California. Pacific Conservation Biology 9:144-151.

White, J. G., R. Gubiani, N. Smallman, et al. 2006. Home range, habitat selection and diet of foxes (Vulpes vulpes) in a semi-urban riparian environment. Wildlife Research 33:175-180.

Opinions expressed on Cool Green Science and in any corresponding comments are the personal opinions of the original authors and do not necessarily reflect the views of The Nature Conservancy.



Comments: What Does the Fox Need?

  •  Comment from Adam Chupp

    Great article Lisa!

    In our paper, we encouraged the park service to increase the suitability of “culturally preserved” habitats (e.g. civil war battlefield sites) for small mammals and other vertebrates. For example, conversion of dense fescue grass fields into native bunch grasses. This would still preserve the cultural interpretation of the site while providing habitat for small animals and prey items for the larger ones. Also, here is a link to an interesting paper about culvert use by a number of different species. It shows that characteristics of the culvert and of the immediately surrounding habitat are important for usage by these species. http://www.berrymaninstitute.org/files/uploads/pdf/journal/fall2012/p._311-326__Sparks.pdf

    Thanks!
    Adam

  •  Comment from Sheri Minnick

    I have a grey foxes living under my shed. They like my mulberry tree. They eat the berries and the animals that are attracted to the tree.

  •  Comment from Jason Fischer

    What a great article!

    So often when we consider the impacts of urbanization on biodiversity, it is easy to overlook the fact that cities can provide habitat for some species. This raises the possibility that cities could be managed and designed in such a way as to support larger wildlife populations and greater levels of biodiversity. Of course, co-existing with urban wildlife has its own set of challenges, as you point out.

    What I find particularly intriguing is the variation in how populations of a single species can respond in different ways to urban development. My favorite example is the kit fox, which avoids cities in much of its range but lives in urban developments in places like Bakersfield, California. What causes such variation in wildlife response, and what does this tell us about how species respond to urbanization and how we might manage urban wildlife differently?

    •  Comment from Lisa Feldkamp

      Thank you!

      I agree, it is very intriguing & there is a lot of interesting work being done on the potential for more biodiversity in cities.

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