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Males don’t listen – even when they’re seabirds

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08.06.2004

Manx shearwaters marry for life and share the incubation and feeding of their single chick. Dr Keith Hamer of Leeds University’s School of Biology has discovered that males consistently provide more food than their wives, but it’s not because they’re better parents – they just don’t listen.

By dangling microphones into burrows of nesting shearwaters, Dr Hamer and Cardiff University colleagues Petra Quillfeldt and Juan Masselo found differences in the way shearwaters respond to the begging calls of their chick.

Dr Hamer said: “We found female behaviour depends on the intensity of the chick’s begging, with mothers of hungry chicks returning very frequently, while those of well-fed chicks stay away for up to eight days. Males return to the nest at least once every four days, bringing back food with predictable regularity, regardless of the chick’s cries.”

The study, which has been accepted for publication in the journal Animal Behaviour, suggests females are either cleverer or more lazy than males – which amounts to much the same thing, according to Dr Hamer. “Females take a break when they can afford to, finding extra food for themselves when they are sure that the chick is not going hungry,” he said.

It seems the chicks are the real winners, ending up twice the weight of their parents, half of which is fat needed to see them through the most difficult period of their lives – leaving home and learning to fend for themselves.

Scientists study life-pairing seabirds to learn about the evolution of parental co-operation and conflict and to discover why different species adopt different sexual strategies such as marrying for life, living in a harem or relying on furtive liaisons during breeding season.

Males provide more food than females in several other species, such as the wandering albatross and giant petrel, but since males of these species are bigger than females, it is hardly surprising they bring home more fish. Shearwater males and females are almost identical, so why mothers don’t provide more for their chicks was unknown until now.

Vanessa Bridge | Source: University of Leeds
Further information: reporter.leeds.ac.uk/499/index.html

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