THE EFFECT OF AN IMPROVED MAN-ANIMAL RELATIONSHIP ON SEX-RATIO IN LITTERS AND ON GROWTH AND BEHAVIOR IN CUBS AMONG FARMED SILVER FOX (VULPES-VULPES)

Earlier experiments indicate that silver foxes' fear of humans can be reduced by humans offering them feed titbits. Sex ratio, cub growth an d behaviour were examined in litters produced by multiparous silver fo x vixens that had been given a titbit twice a week during pregnancy (G 1, N = 14) or received the same amount of human contact without any ti tbit(G2, N = 14). The cubs were tested in an open field (1.15 x 1.15 m square area divided into a 5 x 5 square grid) at 30 days of age, when they were in the early stages of primary socialisation. Cub activity was recorded (number of grid lines crossed [Lc] during 3 min). There w as no treatment-related difference in number of cubs born or cubs wean ed at 49 days (4.9 +/- 0.3 and 4.1 +/- 0.4 vs. 4.8 +/- 0.5 and 3.8 +/- 0.4 for G1 and G2, respectively; NS). However, G1 vixens delivered a significantly higher proportion of male cubs than G2 vixens (64% vs. 5 1%, p < 0.05; G1:3.1 +/- 0.4 male cubs, 1.8 +/- 0.3 female cubs; G2:2. 5 +/- 0.4 male cubs, 2.3 +/- 0.3 female cubs). Female cubs from GI vix ens were more active in the open field (G1:51.4 +/- 4.8 Lc, G2:34.2 +/ - 4.7 Lc, p < 0.05) and heavier (49 days old, G1:1660 +/- 42 g, G2:149 1 +/- 40 g, p < 0.01) than the female G2 cubs. No significant differen ces in activity or live weight were found for male cubs (activity: G1: 46.4 +/- 3.4 Lc, G2:37.1 +/- 4.3 LC, NS; weight 49 days old: G1:1716 /- 29 g, G2:1729 +/- 37 g, NS). Reduced fear of humans during pregnanc y affected the sex ratio in the litter as well as the growth and activ ity of female cubs in the silver fox. (C) 1998 Elsevier Science B.V.