Date: November 9, 2016
Source: Central Ornithology Publication Office
Birds' beaks come in an incredible range of shapes and sizes, adapted for survival in environments around the world. But as a new study from The Auk: Ornithological Advances reveals, there's even more to bird beaks than meets the eye -- the insides of birds' bills are filled with complex structures that help them meet the demands of hot climates.
Nasal conchae are complex structures inside bird bills that moderate the temperature of air being inhaled and reclaim water from air being exhaled. Raymond Danner of the University of North Carolina Wilmington and his colleagues from Cornell University and the National Museum of Natural History used CT scans to examine the conchae of two Song Sparrow subspecies, one that lives in warm, dry sand dunes and one that lives in moister habitats farther inland. In this first comparison of conchae structure from birds living along a moisture gradient, the conchae of the dune-dwelling sparrows had a larger surface area and were situated farther out in the bill than those of their inland relatives, hypothetically increasing their beaks' ability to cool air and recapture water.
Danner and his colleagues used Song Sparrow specimens that were collected in Delaware and the District of Columbia and preserved in ethanol and iodine to help soft tissues show up in scans. The contrast-enhanced CT scans they used to visualize the insides of the sparrows' bills is a relatively new technique that is letting researchers see the details of these soft, cartilaginous structures for the first time.