They may have a reputation for stupidity, but that does not make them gullible. Scientists have found evidence that the blue-footed booby ( Sula nebouxi ) possesses one of the most suspicious minds in the bird world. It has emerged that the male booby would rather destroy his chick before ithatches than take the chance of bringing up a rival's offspring.
Marcela Osorio-Beristain and Hugh Drummond, researchers at the Instituto de Ecologia, Universidad Nacional Autónoma de Mexico, have observed the behaviour of a colony of these birds to find out why they were seen to occasionally destroy their own eggs.
They captured and held 17 males away from their nesting area for up to 12 hours while their female mates were at their most fertile and preparing to lay their first eggs. Another 17 males were similarly treated but their females would not be ready to lay eggs foranother seven to 29 days.
This prolonged absence simulated an extended foraging excursion by the males. During this time, females were observed to display their usual levels of infidelity with other boobies.
However, 43 per cent of those males who were away from the nest when their females were about to lay expelled the first-laid egg from the nest. None of the second group did so.
Osorio-Beristain said that in the five days before laying, females were more likely to seek to mate with other males while their partners put their efforts into guarding their nest against would-be Lotharios.
The research, published in the journal Behavioral Ecology , suggests that the males would often choose to destroy their own eggs as their prolonged absence during their mates' peak fertility raised the prospect of them being cuckolded.
The destruction of the eggs narrowed the chances of them expending precious effort on raising another bird's young.
"We think this is an evolutionary explanation for the males' behaviour, though I do not know of anything similar in other species," said Osorio-Beristain.
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