In mammals, females are the main caretakers of offspring. Males are presumed not to spend time for care and to have no interaction with infants. In several primates, males also spend time to carry infants and share food with them. However, no study which showed quantitative result about interaction between males and infants has been reported.

In feral cat Felis catus also, males have been presumed not to care infants and to have no interaction with infants. We observed, however, considerable male interactions with infants and they stayed with infants for long time in the field. We showed that mean time that infants spent with males was 1.2 times longer than the mean time with mothers.

To reveal why males interact with infants, we conducted behavioural observations on interaction with infants. We measured weights of cats every month for a year and collected hair sample for DNA analysis to quantify the kinship.

We examined the following two questions:

1) Do males interact with related infants?

2) Does males’ interaction raise infants’ growth rate?

3) Do males interact more with female infants than male infants for mate acquisition?