When the pups emerge, both mother and father keep them supplied with solid food until they are completely weaned after two or three months. They leave the den area in mid-July or August and may forage with their parents for another month until the family disbands. Foxes trapped in the fall are often young ones, on their own for the first time and establishing new territories. Both males and females are sexually mature at 10 months and may breed during their first winter. Red foxes seldom seek shelter in holes or dens during winter, preferring to sleep in the open with their bushy, well-insulated tails curled over their noses to keep them warm.
Grays often hole up for three or four days at a time during severe weather.
Foxes may be afflicted with many parasites, including ticks, fleas, lice, mites, flukes and worms. Reds seem to be more susceptible to mange than gray foxes. Both species can contract rabies. Wildlife researchers have live-trapped foxes, tagged and released them. These studies have shown that foxes, especially young adults, are susceptible to many limiting factors, including trapping, hunting, highway mortality and coyote predation.