HIGH PATERNAL INVESTMENT IN UNRELATED YOUNG - EXTRA-PAIR PATERNITY AND MALE PARENTAL CARE IN-HOUSE MARTINS

The response of males to reduced paternity has important consequences for the evolution and maintenance of a mixed reproductive strategy. Pa ternity is predicted to affect directly the level of male parental car e in some cases but not in others. The response of males to reduced pa ternity will be influenced by their ability to assess their paternity, the predictability of cuckoldry and the costs and benefits of parenta l care. Although male house martins (Delichon urbica) provide among th e highest levels of male parental care known in passerines (incubation , brooding and feeding nestlings), there was no evidence that cuckolde d males substantially reduced their level of parental care, and, as a result, all young fledged successfully. Thus, extra-pair fertilization s enhanced the reproductive success of some males because they were ab le to parasitize the parental care of cuckolded males. We discuss seve ral conditions which may favor extensive male parental care even when the male's paternity is very low.