Zebra finches negotiate parental duties through song

By Joshua Izaac 2 December 2015
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A new study has linked duetting with sharing the workload of egg incubation in zebra finches.

ZEBRA FINCHES FORM lifelong monogamous bonds and share egg incubation duties – but how do they negotiate their incubating workloads? By communicating via duets, according to a new study.

The research is the first to find a link between duetting and bird cooperation and negotiation.

Scientists recorded the mutual vocalisations (known as ‘call duets’) of 12 zebra finches (Taeniopygia guttata) as the male returned to the nests to relieve the egg-incubating female. The experiment was then repeated, this time delaying the return of the foraging males to the nest by trapping them in a sound-proof feeder.

“You’re late!”

They found that delaying the males resulted in shorter duets with more calls when the male returns to relieve the female. Not only that, but the female then altered her behaviour in accordance with the modified duet, contributing less to future incubation.

“This shows that a male returning to the nest calls to its partner to indicate how long he is willing to incubate, so the female leaving the nest knows when to come back,” said co-author Mylene Mariette from the Centre for Integrative Ecology at Deakin University in Melbourne.

“Each partner uses the vocal behaviour of its mate during the duet to predict its future behaviour and adjust its own behaviour pre-emptively,” Mylene added.

AUDIO: Zebra finch duet

This finding may have ramifications beyond the bird world – not only is this the first finding of vocal negotiation in birds, but according to biologist Clementine Vignal of the University of Saint-Etienne in France, a senior author of the study, “this is the first time that such a vocal negotiation over parental care [has been] reported in any species.”

In the meantime, the team is interested to see just how complex these vocal negotiations can get. “Some individuals may exaggerate how hungry they are when they return,” suggested Mariette. “So it would be interesting to test whether zebra finches can lie to each other.”

The research was published in the Biological Journal of the Linnean Society.