CT scans reveal birds' built-in air conditioners
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.
|This image created from a 3-D rendering of CT scans shows the nasal conchae inside the bill of a Song Sparrow, |
structures which help it conserve water and regulate the temperature of inhaled air
[Credit: E. Gulson-Castillo and E. Sibbald]
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.
"We had been studying the function of the bird bill as a heat radiator, with a focus on heat loss from the external surface and adaptation to local climates, when we began to wonder about the thermoregulatory processes that occur within the bill," says Danner. "I remember the entire team assembled for the first time, huddled around a computer and looking in amazement at the first scans. The high resolution scans revealed many structures that we as experienced ornithologists had never seen or even imagined, and we were immediately struck by the beauty of the ornately structured anterior conchae and the neatly scrolled middle conchae."
"This study highlights the remarkable complexity of the rostral conchae in songbirds. This complexity has gone largely unnoticed due to the ways in which most birds are collected and preserved," according to Jason Bourke, a researcher from the North Carolina Museum of Natural Sciences who was not involved in the research. "Thanks to the use of innovative techniques like diceCT, we are now able to really appreciate just how complicated bird noses can be."
Source: The Auk [November 12, 2016]