New research sheds light on geographic patterns in shorebird size and shape
New research sheds light on geographic patterns in shorebird size and shape, thanks to long-term data collected by the Victorian Wader Study Group and Australasian Wader Studies Group.
We show that shorebirds from hot, tropical north-western Australia are smaller and have longer bills than members of the same species from temperate, south-eastern Australia. These patterns are consistent across 30 ecologically diverse species, including sandpipers, plovers, terns, stilts, and oystercatchers.
Differences in the size and shape of shorebirds from northern and southern Australia correspond with two eco-geographic ‘rules’ in ecology. Bergmann’s Rule states that animals should be larger at higher latitudes, while Allen’s Rule states that animals should have shorter appendages – such as bird bills – at higher latitudes. Understanding why latitudinal patterns in animal size and shape exist is challenging because there are many possible explanations.
Our findings best support the expectation that differences in shorebird size and shape are driven by adaption to keep cool on the northern Australian coast. This would explain why Arctic-breeding shorebirds that travel to northern Australia have smaller bodies and longer bills than members of the same species that fly to southern Australia. It also explains why we find consistent patterns in body size and bill length across migratory and resident shorebirds. Small bodies and long bills help birds keep cool by providing a greater surface area to dissipate heat. Longer bills are especially advantageous because birds can increase blood flow to the bill’s surface to increase heat loss.
This research helps improve our understanding of the evolution of shorebird size and shape, and how shorebirds might adapt to a warming climate.
Read the full story here: https://doi.org/10.1038/s41467-022-32108-3