Sex-ratio variation and maternal investment in relation to social environment among farmed silver-fox vixens (Vulpes vulpes) of high competition capacity

The sex ratio and body weights of offspring from 13 non-infanticidal farmed silver-fox vixens oi high-competition capacity (HCC), reared under two different neighbouring conditions, were measured. Seven vixens had other HCC vixens as neighbours, whereas the other group had neighbouring vixens of low-competition capacity (LCC). The vixens with LCC neighbours gave birth to and weaned more cubs, with a significantly higher proportion of males (73%), and female cubs of a relatively better HCC neighbours (31% males, female cubs on average 79 g lighter than their brothers). This study indicates sex-ratio regulation in relation to social environment among farmed silver-fox vixens of high-competition capacity. The results are discussed in relation to the future behavioural and reproductive consequences tor the female cubs.