THE ROLE OF STEROID-HORMONES IN SEXUAL AN D AGONISTIC BEHAVIOR IN SILVER FOX MALES

Silver fox males were tested for sexual and agonistic behaviour after introduction of a female at different stages of the reproductive cycle . The high level of aggressive interactions between male and female an d no mountings were observed out of the reproductive season. During th e reproductive season, the introduction of anoestrus female did not af fect the aggressive behaviour but increased the number of mountings wh ile introduction of a receptive female reduced aggressive contacts and augmented sexual behaviour in pairs independently of mating. Consider able variations in testosterone and oestradiol but not cortisol plasma levels were observed between different stages of sexual activity. At the beginning of the reproductive season, silver fox males responded t o anoestrus females with significant increase in their blood levels of testosterone and oestradiol. Contents of these two hormones did not c hange in males during the reproductive season when they encountered a receptive female. A female did not elicit any cortisol response in a m ale during different periods of the reproductive cycle. The data obtai ned suggest that the sexual behaviour in silver fox males can be Facil itated by testosterone and oestradiol while aggressive interactions be tween male and female occur independently of these hormones.