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

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Maximilian L. Allen
Alexandra C. Avrin
Morgan J. Farmer
Laura S. Whipple
Emmarie P. Alexander
Alyson M. Cervantes
Javan M. Bauder


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. 

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Allen, M.L., Avrin, A.C., Farmer, M.J., Whipple, L.S., Alexander, E.P., Cervantes, A.M. and Bauder, J.M. 2021. Limitations of current knowledge about the ecology of Grey Foxes hamper conservation efforts. Journal of Threatened Taxa. 13, 8 (Jul. 2021), 19079–19092. DOI:


Allen, M.L., L.M. Elbroch, C.C. Wilmers & H.U. Wittmer (2015). The comparative effects of large carnivores on the acquisition of carrion by scavengers. American Naturalist 185(6): 822–833.

Allen, M.L., M.S. Gunther & C.C. Wilmers (2017). The scent of your enemy is my friend? The acquisition of large carnivore scent by a smaller carnivore. Journal of Ethology 35(1): 13–19.

Allen, M.L., A. Inagaki & M.W. Ward (2020). Cannibalism in raptors: a review. Journal of Raptor Research 54(4): 424-430.

Anderson, R.E. & J.N. Stuart (1993). The gray fox, Urocyon cinereoargenteus, on the Llano Estacado of New Mexico. The Texas Journal of Science 45(4): 354–355.

Atwood, T.C., T.L. Fry & B.R. Leland (2011). Partitioning of anthropogenic watering sites by desert carnivores. Journal of Wildlife Management 75(7): 1609–1615.

Bakker, V.J., D.F. Doak, G.W. Roemer, D.K. Garcelon, T.J. Coonan, S.A. Morrison, C. Lynch, K. Ralls & R. Shaw (2009). Incorporating ecological drivers and uncertainty into a demographic population viability analysis for the island fox. Ecological Monographs 79(1): 77–108.

Barrett, K.J., E.L. Kalies & C.L. Chambers (2012). Predator occupancy rates in a thinned ponderosa pine forest, Arizona: a pilot study. Wildlife Society Bulletin 36(2): 232–239.

Bauder, J.M., M.L. Allen, A.A. Ahlers, T.J. Benson, C.A. Miller & K.W. Stodola (2020). Identifying and controlling for variation in canid trapper harvest data. Journal of Wildlife Management 84(7): 1234–1245.

Brown, D.J., M.M. Cochrane & R.A. Moen (2017). Survey and analysis design for wood turtle population monitoring. Journal of Wildlife Management 81(5): 868–877.

Borchert, M.I. (2012). Mammalian carnivore use of a high-severity burn in conifer forests in the San Bernardino mountains of Southern California, USA. Hystrix-Italian Journal of Mammalogy 23(2): 50–56.

Boyce, M.S. (1992). Population viability analysis. Annual Review of Ecology and Systematics 23(1): 481–506.

Chamberlain, M.J., J.W. Mangrum, B.D. Leopold & E.P. Hill (1999). A comparison of attractants used for carnivore track surveys. Proceedings of the Fifty-Third Annual Conference of the Southeastern Association of Fish and Wildlife Agencies 53(1): 296–304.

Chamberlain, M.J. & B.D. Leopold (2000). Spatial use patterns, seasonal habitat selection, and interactions among adult gray foxes in Mississippi. The Journal of Wildlife Management 64(3): 742–751.

Chamberlain, M.J. & B.D. Leopold (2002). Movements and space use of gray foxes (Urocyon cinereoargenteus) following mate loss. The American Midland Naturalist 147(2): 409–412.

Chamberlain, M.J. & B.D. Leopold (2005). Overlap in space use among bobcats (Lynx rufus), coyotes (Canis latrans) and Gray Foxes (Urocyon cinereoargenteus). American Midland Naturalist 153(1): 171–179.

Cherry, M.J., K.L. Turner, M.B. Howze, B.S. Cohen, L.M. Conner & R.J. Warren (2016). Coyote diets in a longleaf pine ecosystem. Wildlife Biology 22(2): 64–70.

Constible, J.M., M. Chamberlain & B.D. Leopold (2006). Relationships between landscape pattern and space use of three mammalian carnivores in central Mississippi. American Midland Naturalist 155(2): 252–362.

Cooper, S.E., C.K. Nielsen & P.T. McDonald (2012). Landscape factors affecting relative abundance of gray foxes (Urocyon cinereoargenteus) at large scales in Illinois, USA. Wildlife Biology 18(4): 366–373.

Cortés–Marcial, M., Y.M. Martínez Ayón & M. Briones–Salas (2014). Diversity of large and medium mammals in Juchitan, Isthmus of Tehuantepec, Oaxaca, Mexico. Animal Biodiversity and Conservation 37(1): 1–12.

Cunningham, S.C., L. Kirkendall & W. Ballard (2006). Gray fox and coyote abundance and diet responses after a wildfire in central Arizona. Western North American Naturalist 66(2): 169–180.[169:GFACAA]2.0.CO;2

Davis, M.L., M.J. Kelly & D.F. Stauffer (2011). Carnivore co-existence and habitat use in the Mountain Pine Ridge Forest Reserve, Belize. Animal Conservation 14(1): 56–65.

Deuel, N.R., L.M. Conner, K.V. Miller, M.J. Chamberlain, M.J. Cherry & L.V. Tannenbaum (2017). Gray fox home range, spatial overlap, mated pair interactions and extra-territorial forays in southwestern Georgia, USA. Wildlife Biology

Donadio, E. & S.W. Buskirk (2006). Diet, morphology, and interspecific killing in carnivora. American Naturalist 167(4): 524–536.

Downey, P.J., E.C. Hellgren, A. Caso, S. Carvajal & K. Frangioso (2007). Hair snares for noninvasive sampling of felids in North America: do gray foxes affect success? The Journal of Wildlife Management 71(6): 2090–2094.

Elbroch, L.M. & M.L. Allen (2013). Prey indices and behaviors at a Gray Fox den in San Mateo County, California. Western North American Naturalist 73(2): 240–243.

Eriksson, C.E., K.M. Moriarty, M.A. Linnell & T. Levi (2019). Biotic factors influencing the unexpected distribution of a Humboldt marten (Martes caurina humboldtensis) population in a young coastal forest. PLOS ONE 14: e0214653.

Farias, V., T.K. Fuller, R.K. Wayne & R.M. Sauvajot (2005). Survival and cause-specific mortality of gray foxes (Urocyon cinereoargenteus) in southern California. Journal of Zoology 266(3): 249–254.

Farías, V., T.K. Fuller & R.M. Sauvajot (2012). Activity and distribution of Gray Foxes (Urocyon cinereoargenteus) in southern California. The Southwestern Naturalist 57(2): 176–181.

Fedriani, J.M., T.K. Fuller, R.M. Sauvajot & E.C. York (2000). Competition and intraguild predation among three sympatric carnivores. Oecologia 125(2): 258–270.

Fritzell, E. K. & K.J. Haroldson (1982). Urocyon cinereoargenteus. Mammalian Species 189: 1–8.

Fuller, T.K. & B. Cypher (2004). Gray Fox (Urocyon cinereoargenteus), pp. 92–97. In: Sillero-Zubiri, C., M. Hoffmann & D.W. Macdonald (eds). Canids: Foxes, Wolves, Jackals, and Dogs—Status Survey and Conservation Action Plan. IUCN/SSP Canid Specialist Group, Gland, Switzerland; and Cambridge, United Kingdom.

Gallina, S., P. Lopez-Colunga, C. Valdespino & V. Farias (2016). Relative abundance of the gray fox Urocyon cinereoargenteus (Carnivora: Canidae) in Veracruz central area, Mexico. Revista De Biologia Tropical 64(1): 221–233.

Gehrt, S.D., S.P.D. Riley & B.L. Cypher (eds.) (2010). Urban Carnivores: Ecology, Conflict, and Conservation. The John Hopkins University Press, Baltimore, USA, 304pp.

Glenn, J.L.W., D.J. Civitello & S.L. Lance (2009). Multiple paternity and kinship in the gray fox (Urocyon cinereoargenteus). Mammalian Biology 74(5): 394–402.

Gompper, M.E. (2002). Top carnivores in the suburbs? Ecological and conservation issues raised by colonization of north-eastern North America by coyotes. Bioscience 52(2): 185–190.[0185:TCITSE]2.0.CO;2

Green, D.S., S.M. Matthews, R.C. Swiers, R.L. Callas, J.S. Yaeger, S.L. Farber, M.K. Schwartz & R.A. Powell (2018). Dynamic occupancy modelling reveals a hierarchy of competition among fishers, grey foxes and ringtails. Journal of Animal Ecology 87(3): 813–824.

Gómez-Ortiz, Y., O. Monroy-Vilchis & I. Castro-Arellano (2019). Temporal coexistence in a carnivore assemblage from central Mexico: temporal-domain dependence. Mammal Research 64(3): 333–342.

Greenberg, C.H. & M.R. Pelton (1994). Home range and activity patterns by Gray Foxes, Urocyon cinereoargenteus (Carnivorea: Canidae), in east Tennessee. Brimleyana 21: 131–140.

Haines, A.M., M.E. Tewes, L.L. Laack, J.S. Horne & J.H. Young (2006). A habitat-based population viability analysis for ocelots (Leopardus pardalis) in the United States. Biological Conservation 132(4): 424–436.

Harmsen, B.J., E. Sanchez, O.A. Figueroa, S.M. Gutierrez, C.P. Doncaster & R.J. Foster (2019). Ecology of a versatile canid in the Neotropics: gray foxes (Urocyon cinereoargenteus) in Belize, Central America. Mammal Research 64(3): 319–332.

Harrison, R.L. (1993). A survey of anthropogenic ecological factors potentially affecting gray foxes (Urocyon cinereoargenteus) in a rural residential area. Southwestern Naturalist 38(4): 352–356.

Harrison, R.L. (1997). A comparison of gray fox ecology between residential and undeveloped rural landscapes. Journal of Wildlife Management 61(1): 112–122.

Harrison, R.L. (2002). Estimating gray fox home-range size using half-night observation periods. Wildlife Society Bulletin 30(4): 1273–1275.

Henke, S.E. & F.C. Bryant (1999). Effects of coyote removal on the faunal community in western Texas. Journal of Wildlife Management 63(4): 1066–1081.

Hody, J.W. & R. Kays (2018). Mapping the expansion of coyotes (Canis latrans) across North and Central America. Zookeys 759: 81–97.

Holmgren, M. & S.A. Schnitzer (2004). Science on the rise in developing countries. PLoS Biology 2(1): 10–13.

Hostetler, J.A., J.W. McCown, E.P. Garrison, A.M. Neils, M.A. Barrett, M.E. Sunquist, S.L. Simek & M.K. Oli (2009). Demographic consequences of anthropogenic influences: Florida black bears in north-central Florida. Biological Conservation 142(11): 2456–2463.

Jones, G.D. & J.K. Frey (2008). First record of the gray fox (Urocyon cinereoargenteus) on Texas Barrier Islands. Texas Journal of Science 60(3): 225–227.

Kapfer, J.M. & R.W. Kirk (2012). Observations of gray foxes (Urocyon cinereoargenteus) in a suburban landscape in the piedmont of North Carolina. Southeastern Naturalist 11(3): 507–516.

Karlin, M. & G. De La Paz (2015). Using camera-trap technology to improve undergraduate education and citizen-science contributions in wildlife research. Southwestern Naturalist 60: 171–179.

Kelly, T.R. & J.M. Sleeman (2003). Morbidity and mortality of red foxes (Vulpes vulpes) and gray foxes (Urocyon cinereoargenteus) admitted to the Wildlife Center of Virginia, 1993–2001. Journal of Wildlife Diseases 39: 467–469.

Klymus, K.E., C.A. Richter, N. Thompson & J.E. Hinck (2017). Metabarcoding of environmental DNA samples to explore the use of uranium mine containment ponds as a water source for wildlife. Diversity 9: 54.

Kowalski, B., F. Watson, C. Garza & B. Delgado (2015). Effects of landscape covariates on the distribution and detection probabilities of mammalian carnivores. Journal of Mammalogy 96: 511–521.

LeFlore, E.G., T.K. Fuller, J.T. Finn, S. DeStefano & J.F. Organ (2019). Wild canid distribution and co-existence in a natural-urban matrix of the pioneer valley of western Massachusetts. Northeastern Naturalist 26: 325–342.

Lesmeister, D.B., C.K. Nielsen, E.M. Schauber & E.C. Hellgren (2015). Spatial and temporal structure of a mesocarnivore guild in midwestern North America. Wildlife Monographs 191: 1–61.

Lombardi, J.V., C.E. Comer, D.G. Scognamillo & W.C. Conway (2017). Coyote, fox, and bobcat response to anthropogenic and natural landscape features in a small urban area. Urban Ecosystems 20: 1239–1248.

Lovell, C.D., B.D. Leopold & C.C. Shropshire (1998). Trends in Mississippi predator populations, 1980-1995. Wildlife Society Bulletin 26: 552–556.

Mahard, T.J., J.A. Litvaitis, P. Tate, G.C. Reed & D.J.A. Broman (2016). An evaluation of hunter surveys to monitor relative abundance of bobcats. Wildlife Society Bulletin 40(2): 224–232.

Markovchick-Nicholls, L., H.M. Regan, D.H. Deutschman, A. Widyanata, B. Martin, L. Noreke & T.A. Hunt (2008). Relationships between human disturbance and wildlife land use in urban habitat fragments. Conservation Biology 22: 99–109.

Maxwell, D. & S. Jennings (2005). Power of monitoring programmes to detect decline and recovery of rare and vulnerable fish. Journal of Applied Ecology 42(1): 25–37.

Mcalpine, D., J.D. Martin & C. Libby (2008). First occurrence of the grey fox, Urocyon cinereoargenteus, in New Brunswick: a climate-change mediated range expansion? Canadian Field-Naturalist 122: 169–171.

Mella-Méndez, I., R. Flores-Peredo, J. Pérez-Torres, S. Hernández-González, D.U. González-Uribe & B.D. Bolivar-Cimé (2019). Activity patterns and temporal niche partitioning of dogs and medium-sized wild mammals in urban parks of Xalapa, Mexico. Urban Ecosystems 22: 1061–1070.

Moore, J.E., (1952). The gray fox in Alberta. Journal of Mammalogy 33: 253–253.

Mueller, M.M., D. Drake & M.L. Allen (2019). Using citizen science to inform urban canid management. Landscape and Urban Planning 189: 362–371.

Mumme, R.L., S.J. Schoech, G.W. Woolfenden & J.W. Fitzpatrick (2000). Life and death in the fast lane: demographic consequences of road mortality in the Florida scrub jay. Conservation Biology 14: 501–512.

Nickel, B.A., J. Suraci, M.L. Allen & C.C. Wilmers (2020). Human presence and human footprint have non-equivalent effects on wildlife spatiotemporal habitat use. Biological Conservation 241: 108383.

O’Donnell, K. & J. delBarco-Trillo (2020). Changes in the home range sizes of terrestrial vertebrates in response to urban disturbance: a meta-analysis. Journal of Urban Ecology 6: 1–8.

Omernik, J.M. & G.E. Griffith (2014). Ecoregions of the conterminous United States: evolution of a hierarchical spatial framework. Environmental Management 54: 1249–1266.

Ordeñana, M.A., K.R. Crooks, E.E. Boydston, R.N. Fisher, L.M. Lyren, S. Siudyla, C.D. Haas, S. Harris, S.A. Hathaway, G.M. Turschak, A.K. Miles & D.H. van Vuren (2010). Effects of urbanization on carnivore species distribution and richness. Journal of Mammalogy 91: 1322–1331.

Pearman-Gillman, S.B., J.E. Katz, R.M. Mickey, J.D. Murdoch & T.M. Donovan (2020). Predicting wildlife distribution patterns in New England USA with expert elicitation techniques. Global Ecology and Conservation 21: e00853.

Perez-Solano, L.A., M. Gonzalez, E. Lopez-Tello & S. Mandujano (2018). Medium and large mammals associated with the tropical dry forest of central Mexico. Revista De Biologia Tropical 66: 1232–1243.

Peterson, R.L., R.O. Standfield, E.H. McEwen & A.C. Brooks (1953). Early records of the red and gray fox in Ontario. Journal of Mammalogy 34: 126–127.

Pineda-Guerrero, A., J.F. Gonzalez-Maya & J. Perez-Torres (2015). Conservation value of forest fragments for medium-sized carnivores in a silvopastoral system in Colombia. Mammalia 79: 115–119.

Reed, S.E. (2011). Non-invasive methods to assess co-occurrence of mammalian carnivores. Southwestern Naturalist 56: 231–240.

Rich, M., C. Thompson, S. Prange & V.D. Popescu (2018). Relative importance of habitat characteristics and interspecific relations in determining terrestrial carnivore occurrence. Frontiers in Ecology and Evolution 6: 1–13.

Richmond, N.D. (1952). Fluctuations in gray fox population in Pennsylvania and their relationship to precipitation. Journal of Wildlife Management 16: 198–206.

Riley, S.P.D. (2006). Spatial ecology of bobcats and gray foxes in urban and rural zones of a national park. The Journal of Wildlife Management 70: 1425–1435.

Riley, S.P.D., R.M. Sauvajot, T.K. Fuller, E.C. York, D.A. Kamradt, C. Bromley & R.K. Wayne (2003). Effects of urbanization and habitat fragmentation on bobcats and coyotes in southern California. Conservation Biology 17: 566–576.

Roemer, G., B. Cypher & R. List (2016). Urocyon cinereoargenteus. The IUCN Red List of Threatened Species 2016: e.T22780A46178068.

Rota, C.T., M.A.R. Ferreira, R.W. Kays, T.D. Forrester, E.L. Kalies, W.J. McShea, A.W. Parsons & J.J. Millspaugh (2016). A multispecies occupancy model for two or more interacting species. Methods in Ecology and Evolution 7: 1164–1173.

Sawyer, D.T. & T.T. Fendley (1994). Seasonal habitat use by gray foxes on the Savannah River site. Proceedings of the Forty-Eighth Annual Conference of the Southeastern Association of Fish and Wildlife Agencies 162–172.

Schantz, V.S. (1950). The gray fox in North-Dakota. Journal of Mammalogy 31: 197–198.

Schuler, K.L., G.M. Schroeder, J.A. Jenks & J.G. Kie (2014). Ad hoc smoothing parameter performance in kernel estimates of GPS-derived home ranges. Wildlife Biology 20: 259–266.

Schwertner, T.W., M.J. Peterson & N.J. Silvy (2006). Multi-scale asynchrony and spatial structuring of mesopredator abundance trends in central Texas, 1978–2003. Texas Journal of Science 58: 155–168.

Sillero-Zubiri, C., M. Hoffmann & D.W. Macdonald (2004). Canids: foxes, wolves, jackals and dogs. Status Survey and Conservation Action Plan. IUCN/SSC Canid Specialist Group. Gland, Switzerland.

Swaisgood, R.R., D. Wang & F. Wei (2018). Panda downlisted but not out of the woods. Conservation Letters 11: e12355.

Temple, D.L., M.J. Chamberlain & L.M. Conner (2010). Spatial ecology, survival and cause-specific mortality of gray foxes (Urocyon cinereoargenteus) in a longleaf pine ecosystem. The American Midland Naturalist 163: 413–422.

Trapp, G.R. (1978). Comparative behavioral ecology of ringtail and gray fox in southwestern Utah. Carnivore 1: 3–32.

Walk, J.W., M.P. Ward, T.J. Benson, J.L. Deppe, S. Lischka, S.D. Bailey & J.D. Brawn (2010). Illinois birds: a century of change. Illinois Natural History Survey Special Publication 31, Champaign, USA.

Walters, J.R., S.R. Derrickson, M.D. Fry, S.M. Haig, J.M. Marzluff & J.M., Wunderle Jr. (2010). Status of the California condor (Gymnogyps californianus) and efforts to achieve its recovery. The Auk 127: 969–1001.

Walton, Z., G. Samelius, M. Odden & T. Willebrand (2017). Variation in home range size of red foxes Vulpes vulpes along a gradient of productivity and human landscape alteration. PLoS ONE 12: e0175291.

Wang, Y., M.L. Allen & C.C. Wilmers (2015). Mesopredator spatial and temporal responses to large predators and human development in the Santa Cruz Mountains of California. Biological Conservation 190: 23–33.

Ward, R.J., R.A. Griffiths, J.W. Wilkinson & N. Cornish (2017). Optimising monitoring efforts for secretive snakes: a comparison of occupancy and N-mixture models for assessment of population status. Scientific Reports 7(1): 18074.

Weston, J.L. & I.L. Brisbin (2003). Demographics of a protected population of gray foxes (Urocyon cinereoargenteus) in South Carolina. Journal of Mammalogy 84: 996–1005.

Zielinski, W.J., R.L. Truex, F.V. Schlexer, L.A. Campbell & C. Carroll (2005). Historical and contemporary distributions of carnivores in forests of the Sierra Nevada, California, USA. Journal of Biogeography 32: 1385–1407.