by Dave Hanks
The bodies of all of us, both human and animal, have homeostatic mechanisms. These are both physiological and behavioral. Homeostasis means a state of constancy. The body must maintain its functions on a steady plain. If we’re too hot, we sweat; if we are too cold, we shiver; if we are sick to our stomach, we vomit. We could, also, turn on the air conditioner, or turn up the furnace, or take some Alka Seltzer. These are all examples of how we keep our bodies running on an even keel.
Waterfowl, with basically the same problems as ours, do basically the same things. “WATER RUNS OFF A DUCK’S BACK” is true, but only with a little homeostatic help – both physiological and behavioral. When trying to photograph waterfowl, it can be disconcerting when they won’t remain still – always fixing their feathers and probing at their tail. There is an oil gland at the base of the tail. The oil is the body’s answer for water proofing feathers, but can’t reach its destination without some help.
BARROW’S GOLDENEYE (pictured) is a northern species that graces our area’s open water during the winter months. By staying dry, their hollow, air trapping, feathers will protect them from the cold. To do this the feathers must repel the cold water. Hence, the duck rubs oil up and down each feather’s shaft. The feather filaments each have barbules which hook on to the adjoining filament. This forms a continuous covering to keep out the wet. When you observe the bird preening, they are doing two things. They are re-hooking the barbules and oiling their feathers. Also, without this constant oiling and barbule hooking, the bird would be unable to fly because the feathers would be waterlogged, and the unhooked feathers would be unable to trap air.
Comfortable swimming in an icy pool