Ecology and behaviour: Growing up

A close up of young fox cub groomed by its mother
One month old fox cub
© The Fox Website

When fox cubs are born they are completely dependent upon their mother for food and warmth. They are deaf and blind, weigh about 100 grammes, are 10 centimetres long and have short black fur. For the first couple of weeks the mother rarely leaves them and depends on the male and probably other foxes for food. At this point, the cubs' eyes start to open and they can start exploring their den.

A one month old fox cub
1-2 month old fox cub
© The Fox Website

At about four weeks of age, the cubs venture outside but remain very close to the den. They are beginning to moult into a more familiar reddish colour. A couple of weeks later the moult is completed, they are covered in reddish/orange fur and their faces have a more vulpine shape: the ears and the snout grow longer.

At this stage, cubs are very active, playing for long periods chasing each other or chewing a variety of objects that they find. This is the time when most of the complaints about urban foxes occur as vegetables and plants get flattened or chewed.

A close up of a large cub being groomed by another fox
Foxes are attentive parents; © Everything is permuted

When 12 weeks old, the cubs start following the adults more and probably learn where to find food as now they will start foraging for themselves. Many cubs die at this age. By the time they are 16-18 weeks the cubs are able to find food independently from the adults but their movements are still restricted, only covering part of their range. Even by the time they disperse, they are not yet covering the full natal range.

At six months they are hard to tell from the adults and by the age of 10 months they are fully grown and able to breed.

Question & Answer

TopWhat do fox cubs eat?

A graph showing the diet of fox cubs in London
The diet composition of fox cubs in London. Text description of this file is available on a separate page

From birth until four weeks of age, fox cubs rely on their mother's milk. After this period, the cubs start to take solid food, although they continue to take milk for some weeks longer.

The food provided by the adult foxes largely depends on what is available in the territory where the fox family lives. In rural areas rabbit form the majority of the diet whilst in cities foxes eat anything from bread to meat bones and small birds. However, the parents prefer to bring large items of food (such as rabbits or squirrels) to the den as they can be split among the cubs.

TopWho feeds the cubs?

To a certain extent, all members of a fox group, not just the cubs' parents, will feed the cubs. For instance, where food is abundant, as in most urban environments, additional family members may help raise cubs alongside the parents. These are usually (but not always) offspring from previous years who have reached adulthood but, instead of dispersing to look for their own territory, have remained on their parents' territory.

In Bristol, researchers investigated the benefits these additional foxes called 'helpers' bring - if any - to the group as a whole. They looked at fox groups of different sizes and asked whether larger groups raised more cubs. They found that all foxes in a group contributed to feeding the cubs to varying degrees, with male members of the group tending to bring more food to the cubs than females. However, the presence of helpers did not increase cub survival but the more helpers there were, the less hard the parents had to work to feed the cubs.

TopWhat do fox cubs play with?

The array of play items around a fox den is truly impressive: it ranges from shoes, to golf balls, gloves and puppets, as well as a wide range other food items. Fox cubs also spend long hours play-fighting, chasing each other and playing tug-of-war with food or objects.

TopWhat happens to the cubs?

A graph showing the percentage mortality causes of fox cubs in London and Bristol
Causes of fox cub mortality in London and Bristol in the late 1970s. Text description of this file is available on a separate page

Many more cubs are born than survive. Most cubs never reach their breeding age, dying before they are 10 months old.

A lot of the male cubs and a few of the females still alive at six months of age disperse, leaving their natal area to try to find a suitable territory in which to breed. Surplus animals i.e. those that do not find a territory, generally die younger than territorial animals.

References

  • Baker, P.J., Robertson, C.P.J., Funk, S.M. & Harris, S. (1998) Potential fitness benefits of group living in the red fox, Vulpes vulpes. Animal Behaviour 56, 1411-1424.
  • Harris, S. (1981) The food of suburban foxes (Vulpes vulpes), with special reference to London. Mammal Review 11, 151-168.
  • Harris, S. & Baker, P. (2001) Urban foxes. Whittet Books, Suffolk.
  • Larivière, S. & Pasitschniak-Arts, M. (1996) Vulpes vulpes. Mammalian Species 537, 1-11.
  • Lloyd, H.G. (1980) The red fox. Batsford, London.
  • Nowak, R. M. (2005) Walker's carnivores of the world. John Hopkins University Press, Baltimore, Maryland, USA.