In the spirit of Thanksgiving, Improbable Research asks the very question you all were wondering.
The snood - the long fleshy appendage above the beak, is what erects, becoming red as it engorges with blood. (The snood photo we reproduce here is from the Homegrown Hobby Farm blog.) Rebecca T. Kimball and Edward L. Braun of the University of Florida explain at least part of the story, in their study:
"A multigene phylogeny of Galliformes supports a single origin of erectile ability in non-feathered facial traits," Journal of Avian Biology, vol. 39, 2008, pp. 438-45. The authors report:
Species within the Phasianidae (pheasants, partridges, guineafowl, grouse and turkeys) are well known for extreme ornamental traits, including fleshy regions around the head and neck…. Many species in the avian order Galliformes have bare (or ‘‘fleshy'') regions on their head, ranging from simple featherless regions to specialized structures such as combs or wattles…. [The] ability to erect rapidly the fleshy traits is restricted to a single, well-supported lineage that includes species such as the wild turkey Meleagris gallopavo and ring-necked pheasant Phasianus colchicus.
(Thanks to investigators Simon Kasif and Rich Roberts for bringing this to our attention.)
BONUS: A CT-Scan-based animation of the anatomy of an unengorged turkey snood, prepared by the Witmer lab at Ohio State University (thanks to Maggie Koerth-Baker of Boing-Boing for bringing it to our attention):
This post originally appeared on Improbable Research.