Confusing Fall Ducks

In a few months, St. Marks NWR will be at the height of the winter season. Over two thousand ducks representing nineteen different species will be scattered across the refuge’s ponds, pools and nearshore waters. Because ducks choose their mates on their wintering grounds, these ducks will be in their bright, distinctive breeding plumages making identification relatively easy. Most Big Bend birders learn ducks in winter by studying males in breeding plumage. That’s what we think ducks should look like. Female ducks with their drabber plumage are just the ones hanging out with the males.

However, in early Fall, duck identification may not be so easy. Like most birds, ducks molt between two different plumages over the course of the year.  With the exception of Wood Ducks, all of St. Marks’ wintering ducks are Northern breeders. Once they have finished breeding and before they migrate South, ducks molt into their non-breeding plumage, a drab camouflage pattern. During this molt, they lose all of their wing feathers at once, becoming flightless for a short period. This is the only time of the year that ducks molt their wing feathers.

Being flightless is dangerous and ducks put all of their molt energy into regrowing their wing feathers first. Our earliest Fall arrivals migrate just after regrowing their wing feathers and their body feathers are either still in drab non-breeding plumage or may be in an intermediate state between non-breeding and breeding plumage. Even though the earliest migrants are males, they lack most of the identifying marks that we look for. A sitting Blue-winged Teal at the refuge in September or a Northern Shoveler in early October won’t look like we expect them to. Blue-wings arrive in August, but some won’t complete their breeding molt until November. Shovelers arrive later, but are the last species to complete their molt and some won’t be in breeding plumage until December.

Some ducks in October and November arrive in flocks exhibiting mixed plumages with some birds in full breeding plumage, but others that are still transitional. This is true of American Wigeon, Green-winged Teal, Northern Pintail and Redhead in October and of Lesser Scaup and Red-breasted Merganser in November.

Gadwall, Mallard, Canvasback, Ring-necked Duck, Greater Scaup, Hooded Merganser and Common Goldeneye usually complete their molt into breeding plumage before they get to St. Marks. Most of these species are later migrants and don’t arrive until November, giving them more time to finish molting before they arrive.

There are a few important exceptions. Geese and sea ducks take more than one year to attain adult plumage and may arrive at St Marks in breeding, non-breeding or juvenal plumage. Ruddy Ducks are always in non-breeding plumage in winter, but Ruddy Ducks are like that.

So, what’s a birder to do in early Fall when ducks may be partly through their molt and have that mottled brownish generic duck look? You can always look at the wing pattern if a duck is flying. Ducks only molt their wing feathers once a year and always have the expected wing pattern. A Blue-winged Teal always has its blue wing patch.

There are other keys to use for identifying ducks; habitat, behavior, voice and shape. 

Habitat and behavior are tied together. That’s how different species of ducks get their food. Diving ducks, like Scaup, Redhead and Canvasback, prefer deeper water; dabbling ducks, the ones that tip forward with their butts in the air, like Mallards, Gadwall and Wigeon, prefer to work the marshes and shallow water along pond edges. 

Ducks don’t just quack. Some species have distinctive calls like the squealing call of a female Wood Duck or the airy whistle of an American Wigeon and even the quackers can be differentiated with practice.

Shape, along with size and body proportions, can identify duck species without regard to field marks. Look for the Northern Pintail’s long neck; the diminutive size of Green-winged Teal or the long spatulate bill of the Northern Shoveler.

Ducks at St. Marks in early Fall can be confusing which can lead to birder frustration or to misidentifications from attempts to identify ducks in intermediate plumages that don’t match anything in the field guides. If you’re up for a challenge, use shape, voice, behavior or try to get a look at the wing pattern in order to make an accurate identification.  If you’re a novice at duck identification, it’s okay to simply note “duck” and wait until later in the season when ducks look like the pictures in the field guide.

You can always spend your time working on Fall warblers.