The costs and benefits of red fox dispersal

A completed PhD study by Carl Soulsbury funded by NERC and supervised by Prof. Stephen Harris and Dr Philip Baker.

fox sitting
© Mammal Research Unit
Photo by Jane Bowry

Dispersal is a key process in biological sciences. Dispersal is the movement of individuals from the territory on which it was born, to a different territory where it may later breed. This process involves movements of individuals, and this makes dispersal important in the conservation of isolated populations and the spread of diseases or invasive species. Dispersal is also important in shaping the sociobiology of species and it is this that my study is focusing on.

The red fox (Vulpes vulpes) is a highly successful member of the the Canidae. Red foxes are highly adaptable and have colonised a wide range of habitats, including urban areas. This ecological plasticity has also affected red fox sociobiology with a wide variaton of spatial organization, mating systems and sociality being found across the world. Conditions in the urban environment mean foxes can have small territories and can allow the formation of groups. In the early 1990's fox densities were very high and groups of related individuals were commonplace. During this time, studies focused on the individuals that did not disperse and the benefits these individuls may accrue. However dispersal is an important strategy and this study aims to look at why foxes disperse and also why they may not. The synergistic relationship between the the costs and benefits of dispersal and the costs and benefits of philopatry are the primary mechanisms for group formation.

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Most studies that examine costs of dispersal assume that dispersing individuals suffer a higher rate of mortality. This is thought to be due to an increased risk of predation. It is unlikely that the urban popualtion of foxes here in Bristol suffer such a risk, so this study is incoporating other 'costs' that might be associated with dispersal. As well as mortality, I am examining the role injuries, nutrional stress and missed breeding might have on dispersal as a strategy. As well as radiotracking, my study incoporates physiological work and genetics analysis. Radiotracking is the glue to my study as it is the dispersal behaviours that links together why dispersal might be costly, and also why it might not.

Part of this research has recently been published:

Iossa, G, Soulsbury, CD, Baker, PJ & Harris, S. (2008) Body mass, territory size and life-history tactics in a socially monogamous canid. Journal of Mammalogy: in press

Soulsbury, CD, Iossa, G, Baker, PJ & Harris, S. (2008) Environmental variation at the onset of independent foraging affects full-grown body mass in the red fox. Proceedings of the Royal Society B: Biological Sciences: in press.

Soulsbury, C.D., Baker, P.J., Iossa, G. & Harris, S. (2008) Fitness costs of dispersal in red foxes (Vulpes vulpes). Behavioral Ecology and Sociobiology 62: 1289-1298.
doi: 10.1007/s00265-008-0557-9

Soulsbury, C.D., Iossa, G., Edwards, K.J., Baker, P.J. & Harris, S. (2007) Allelic dropout from a high-quality DNA source. Conservation Genetics 8: 733-738.
doi: 10.1007/s10592-006-9194-x

Soulsbury, C.D., Iossa, G., Baker, P.J., Cole, N.C., Funk, S.M. & Harris, S. (2007) The impact of sarcoptic mange Sarcoptes scabiei on the British fox Vulpes vulpes population. Mammal Review 37: 278-296.
doi: 10.1111/j.1365-2907.2007.00101.x

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Contact details

Dr Carl Soulsbury
Mammal Research Unit
School of Biological Sciences
University of Bristol
Woodland Road
Bristol BS8 1UG, U.K.

Telephone: 0117 9288918
Email: Dr Carl Soulsbury