Hens ( Gallus gallus domesticus ) with larger spurs have higher faecal testosterone levels; evidence of female to male - like phenotype

Spurs are a testosterone-dependent secondary sexual characteristic of male chickens ( Gallus gallus domesticus ) and are used as ‘weapons’ in intra-sexual fighting. While predominantly a male feature, they are also found in a small number of females. Here we show that faecal testosterone metabolites of adult hens (i.e. females) with large spurs are significantly greater than those of females with smaller spurs. The presence of spurs in hens together with elevated testosterone levels are indicative of a masculinisation process that may increase with age. This is of particular interest in the study of female to male sex-reversal in fowl.