Cheating budgies do it out of sight

New Scientist, 07 June 1997

A MALE budgerigar is far more likely to be tempted into an illicit affair when out of sight of his vengeful mate, say scientists from New York. They suspect that males want to avoid getting into trouble with their partners—or even being dumped altogether.

Aliza Baltz and Anne Clark, behavioural ecologists at Binghamton University in New York, say that budgies (Melopsittacus undulatus) usually live in stable pairs when raising their young. During the breeding season, males bring home the food while females guard the fledglings in the nest.

Baltz and Clark studied 13 pairs of budgies as they were starting to breed. They watched each pair interact in the home cage for 30 minutes, then put the male in a cage about 1 metre away. Next to the male's cage, behind a screen, was a caged female he had not yet met.

The researchers then gave each male two chances to interact with the new female—once while under the stern eye of his mate, and once while she was concealed behind a screen. Baltz and Clark recorded the number of times the males engaged in bouts of head-bobbing, their distinctive courting behaviour. It turned out that almost three-quarters of the action occurred while their mates could not see them.

To exclude the possibility that males interacted with the female simply because they were lonely when their mate was out of sight, the researchers replaced the female with a male. The level of male-male interaction was the same whether or not the female partner was looking.

"Male fidelity may be a quick, accurate indicator of his parental quality," say the authors in Animal Behaviour (vol 53, p 1017). Courtship with other females conflicts with the male's reproductive duties, they say. When free in aviaries, the more time males spend flirting with other females the less time they spend at the nest. Errant males also raise fewer offspring.

Males may hide their infidelity to avoid being turfed out and replaced. "Replacing him would not be a big deal," says Clark. They may also want to avoid being henpecked. When reunited with their mates, the males that had been caught cheating were subjected to beak jabs and shrill, disapproving chirps.