This is the time of year we see beautiful and dramatic color changes in the vegetation, but that is just one of many fall transformations. Gaudy male ducks that shed those brilliant colors right after donating their sperm to the next generation last spring and became pale, cryptic versions of their previous selves have recently begun the transformation back to splendid technicolor. It’s like a before and after makeover for Mallard Ducks at the local reservoir this week.
Most ducks undergo two feather molts during the course of one year: one in the spring/summer after breeding in which they replace all of their feathers, including flight feathers (resulting in the basic/female-type plumage); and one in the fall/winter in which they replace just the body feathers to regain the colors of the breeding (nuptial) plumage.
This process of feather replacement ensures that birds acquire a new set of flight feathers before making short or long-distance migrations in fall or spring. More importantly, it ensures that gaudy male ducks, who would be conspicuous targets for aerial predators (like Bald Eagles) can protect themselves with better camouflage while they are flightless and molting a completely new set of wing feathers.
Fueling this feather replacement not only demands additional energy intake per day, but a higher quality of protein in the diet, and so ducks will start feeding on more invertebrates and less pond scum, as they drop old feathers and grow in new ones. It has been estimated that ducks need to ingest about 100 grams of protein to replace the 60+ grams of body feathers during a whole body feather molt. That means they need to ingest more than 3 grams of protein per day over the 30 day molting period, and that translates to about 31,000 invertebrates eaten over the month!!!, according to the folks at Ducks Unlimited.