title: The behaviour of adult male Long-Evans rats Rattus norvegicus toward pups of different ages.
abstract: Adult male Long-Evans rats were presented with 1-7 or 14-21 day old pups for 20 days. Pups were changed every 12 h and each male received pups from three litters, with litters changed every week. Pup-related activities were observed for two 15-min periods each day. Males with young pups had a shorter latency to crouch over and carry pups while males with older pups showed a shorter latency to lick pups. Males with young pups had higher nest ratings, and engaged in more nest building, crouching over and carrying pups than males with older pups, while males with older pups spent more time touching, sniffing, and licking pups. Both groups of males showed an increase in pup-related behaviour over the first 8-10 days of pup exposure and a decrease in pup-related behaviour when the litters were changed. These results indicate that pup age is an important factor in determining male behaviour. Males direct parental behaviour toward neonatal pups and affiliative behaviour toward older pups. The importance of affiliative behaviour with adult males in the social development of juvenile rats is discussed.
authors.affiliation: Psychology Department, Dalhousie University Halifax, Nova Scotia B3H 4J1, Canada.
authors.forename: R E
authors.initials: RE
authors.lastname: Brown
authors.forename: S
authors.initials: S
authors.lastname: Douglas