Co-parenting shorebirds’ defence habits indicate how they divide responsibility

Shorebirds gathered on a beach

Many species of shorebirds are adept at co-parenting by sharing the responsibility of sitting on their nest of eggs, but an international collaboration of researchers, including a professor from York University’s Glendon College, has found that the amount of time each parent sits on the nest may be determined by their method of fending off predators.

Shorebirds are efficient at co-parenting
Shorebirds are efficient at co-parenting. Above: Marbled godwit. Image: Wikimedia Commons

The birds that use camouflage to defend against predators will have one parent sit on the nest for up to 50 hours before the other one takes a turn. Researchers believe this is to minimize rustling and movement around the nest that may alert predators to its presence.

Birds that defend their nest by aggressively mobbing predators will spell each other off more frequently; sometimes 20 times a day.

“The amount of diversity in incubation behaviour, both within and among species, was truly impressive.  Also, revealing that the risk of predation, not the risk of starvation, may drive this diversity, highlights the importance of predation risk in shaping the reproductive ecology of shorebirds,” said York U biology Professor Laura McKinnon.

The research was led by doctoral student Martin Bulla and Professor Bart Kempenaers of the Max Planck Institute for Ornithology and involved 76 researchers who studied how shorebird parents divided up their time on the nest and why.

They showed that the parents synchronize incubation duties, which varied widely within and between species. The behaviour did not follow circadian rhythms or light and dark patterns, suggesting the pairs create their own synergy by synchronizing with each other.

The team looked at data from 729 nests of 91 populations of two-parent, incubating shorebirds in a variety of locations. The study was published in the journal Nature.