A pair of foxes were in the obs garden this afternoon mating. The mating resulted in the animals getting stuck together, a phenomenon called 'Copulatory Tie'. There is a bone like structure in the penis called the baculum and the tip of this swells in an area of tissue called the bulbus glandis. This swelling causes the male and female to get locked together. Release occurs when the swelling is reduced following ejaculation. Source Here . It can last for up to 90 minutes but these two got unlocked after about 30 minutes.