Red fox (Vulpes vulpes) has the widest range of any terrestrial carnivore (click for range map), a result of their intelligence and their ability to eat whatever food is available and to maximize their breeding success in a variety of conditions, from deserts to lush forests. Red foxes have also proved adept at adapting to human modified environments, and can thrive in agricultural and low density housing areas.
Since spring is in the air, we start with breeding strategies. Red foxes typically form monogamous pairs throughout the breeding season. Courtship begins in the winter, where the foxes hunt together, play, and generally chase each other around, and lasts about 2 weeks. Even though courting foxes are very playful, if you see two foxes growling and fighting you are usually seeing a fight over territory rather than breeding. After courtship and breeding the pair will split up for some time alone, but after the female enters the birth den the male returns and stays with the female the rest of the season as a monogamous pair, bringing food to the pups and helping to raise the litters.
Red foxes have two strategies to increase breeding success. One is that female pups from the year before will often stay with the family and help raise the kits. These helpers are always female and they are always subordinate to the breeding female. This strategy is quite common, with almost a third of fox dens typically having extra helpers. The second success strategy is that in time of abundant food, males will mate with up to 2 females, and the females may even den together, although this is a bit unusual. Males are not known to mate with more than 2 females, likely due to the burden of providing food to multiple litters.
Foxes also have several different foraging styles that let them find food in almost any habitat. Foxes will hunt mice in a manner similar to coyotes, listening for mice rustling in the grass with their head held high and pouncing in a large graceful arc upon their hapless prey. They will also stalk larger prey, bursting from cover and running down rabbits or leaping into the air to catch flushing birds. Foxes are also accomplished scavengers and spend large amounts of time thoroughly searching an area for all possible food items including insects, human garbage, berries and other fruit, and caches made by other foxes. Foxes keep track of areas they have already searched by peeing almost every minute, leaving a scent record of areas they have searched so they can efficiently cover their territory. Red fox urine has a skunky odor, so the next time you are passing a stump, rock wall, or another elevated object and catch a whiff of skunk, you may just have wandered by a red fox scent post instead.
For more information about red foxes see:
Elbroch, Mark and Kurt Rinehart. Behavior of North American Mammals. New York: Houghton Mifflin, 2011. 374 pgs.
Lariviere, S. and M. Pasitschniak-Arts. 1996. Vulpes vulpes. Mammalian Species. 537:1-11.