New Publication: Habitat-specific divergence of air conditioning structures in bird bills

“We used high precision computed tomography (CT) and traditional radiography to study the nasal conchae, complex structures within the nasal cavity that condition air via countercurrent heat exchange. Concha size differed between 2 subspecies of Song Sparrow (Melospiza melodia) that inhabit climatically distinct habitats, suggesting adaptation to local climates. The conchae and external bill are nested structures that were positively related in size and play functionally related roles in thermoregulation, therefore suggesting phenotypic integration. We hypothesize that the typically deeper and wider bill of the dune subspecies has evolved, at least in part, to accommodate larger conchae.”

– Lead author, Raymond Danner

Head over to The Auk to see the the published image sets!

DiceCT sparrow nasal cavities
Frontal cross sections along the bills in 2 Song Sparrows prepared using alcoholic iodine (I2E), illustrating the differences between (A) M. m. atlantica and (B) M. m. melodia. Sections are ordered sequentially, from caudal-most to rostral-most. Within each cross section, the top is dorsal and the bottom is ventral. (Scale bar is 2.0 mm.)

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