For species in which both parents work together to raise their offspring, cooperation is key — it’s as true for birds as it is for people. A new study from The Auk: Ornithological Advances shows that pairs of Common Murres update each other on their condition so that when one partner needs a break, the other can pick up the slack.
Common Murre parents trade duties throughout the day — one stays at the nest while the other leaves to find a fish for the chick. Because brooding the chick requires much less energy than foraging, staying at the nest is preferable for a bird that’s in poor condition.
Linda Takahashi, Anne Storey, and Carolyn Walsh of Newfoundland’s Memorial University, along with Sabina Wilhelm of the Canadian Wildlife Service, studied the “turn-taking ceremony” that parents perform when they switch places. They found that the time they spend preening each other provides a way for the two birds to exchange information about how they’re doing, so that if one is in poor shape the other can compensate.
The researchers observed 16 pairs of murres with chicks on an island off the coast of Newfoundland in summer 2009, recording their behavior when parents switched duties at the nest and capturing the birds to check their body condition.
Their results show that nest-relief interactions take longer when one partner is especially low in body mass, suggesting that when brooders withhold preening and stall their departure, they’re letting their mates know that they need more time to rest; the returning mate can then compensate by going off to forage again rather than trading places immediately. Similarly, the brooding mate might let a struggling returner take over at the nest even if it hasn’t brought back a fish.
“The roles of avian pair members have been much studied in terms of energy investment and food delivery, but we are accustomed to thinking of these problems in terms of evolutionary tradeoffs. The ways in which contributions are actually negotiated within individual pairs has, until recently, been largely overlooked,” says seabird researcher Tony Gaston of Environment Canada. The murre research “addresses this deficiency, and this is a field which promises to open up additional avenues of research on within-pair communication.”
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