Partitioning of Parental Care in the Leaden Flycatcher

Abstract

Leaden Flycatchers Myiagra rubecula are sexually dichromatic spring and summer visitors to south-eastern Australia. Twelve pairs were observed for 661 hours throughout the 1993–94 breeding season. These pairs made repeated nesting attempts, due to a high failure rate (young fledged from only 23% of nests that received eggs). Investment by male and female parents was very similar at all stages of nesting, though females contributed slightly more to incubation (55% of time) and brooding of nestlings (58% of time) and incubated eggs and brooded nestlings overnight. The pattern of parental investment is similar to that shown by the Willie Wagtail Rhipidura leucophrys, a sedentary, sexually monochromatic flycatcher. We suggest that parental investment is so similar between the sexes in these flycatchers because the very low breeding success means that the potential benefits of seeking extra-pair copulations by males will be lower than the benefits of investing in the few nests that reach the later stages of breeding.