The behaviour of mature male sperm whales on the Galapagos Islands breeding grounds

Physeter macrocephalus were observed between 1985 and 1991. The abundance of males peaked in April and May at 3% of the population. Only 1 of the 18 photographically identified males was sighted off the Galapagos in two different years. In their residency periods off the Galapagos and their lack of preferred ranges, and in many aspects of their behaviour, males were similar to females. However, unlike females, males were sometimes seen alone and never performed any aerial behaviour. Further evidence is consistent with males' maximizing their expected reproductive success by roving between groups of females. -from Author