Male New Zealand robins have worked out a way to keep their mate happy: making sure they bring her the right food.
New research from Victoria University of Wellington shows the wild male birds read their partner's behaviour to make sure they bring her the food she wants.
Dr Rachael Shaw conducted the study on a group of North Island robins based at Wellington's Zealandia.
She said robins were monogamous and food sharing, but the mating pairs still showed an impressive level of communication.
"We found male robins appropriately catered to their mates' desire, even when the female's behaviour was the only cue available to guide their choices.
"This suggests that females can signal their current desires to their mates, enabling males to respond to that."
The researchers first investigated the female robins' eating habits, by feeding them either mealworms or waxworms.
They were then given the choice between the two types of insect larvae. The researchers found the female would pick to eat the other type on the second time around.
They then tested if the male would be able to choose the insect his partner would be likely to want to eat.
They found that, whether or not he'd seen what she'd eaten previously, the male still usually made the appropriate choice.
"This suggests that the female is likely to be displaying her current desire in her behaviour, and that the male is using these cues to identify the food she wants," Shaw said.
The experimental research has previously only been carried out in a lab setting, on Eurasian jays.
Shaw said the finding raised the possibility that other species might be capable of similar food sharing rituals.
"In many species food sharing by the male is vital to help the female offset the energetic costs of reproduction, such as egg laying and incubation.
"The male's ability to give his mate what she wants could be an important factor in determining the success of a pair, as well as influencing whether they stay together."
The research was supported by the Rutherford Foundation postdoctoral fellowship, and a Marsden Fast Start grant from the Royal Society of New Zealand.
Field work and data collection was carried out by Shaw with help from Victoria University student Regan MacKinlay.