Richards, M. 1969. Effects of oestrogen and progesterone on nest building in the golden hamster. Animal Behaviour 17, 356-361.

Nest building in golden hamsters was measured by daily removal and weighing of nests built with straw pulled in from a supply outside each cage. Females used increasing amounts of straw as pregnancy advanced. Similar increases were seen in spayed females given implants of oestrogen and progesterone. Implants of either oestrogen or progesterone alone had no effect. Implants of oestrogen and progesterone did not increase nest building in intact or castrate males. This sex difference was not modified by castrating males or injecting females with testosterone in infancy.