One nice thing about a spotting scope: it isolates your focus down to one or a couple of individual birds. If it's on a tripod, you can hold a birding book in one hand, while you look for distinguishing characteristics.
At a glance, what stands out:
- orange yellow legs
- black beak (on the one that is visible)
- dark eye
- a fairly large rounded head that is a bit squared at the back
- a black rump on the two brighter individuals
- two sets of a bright individual and a drab individual, so possibly two pairs
- a white patch on the secondary wing feathers–near where the wing is close to the body; both the possible males and females have this white wing patch
- and if the two brighter ducks are drakes (males), they are not flashy and colorful like mallards
It doesn't seem like a lot, but it is. Additional important info is the location and the time of year.
Malibu Lagoon on the Southern California coast in February.
A quick paging through ducks in my Sibley Guide to Birds finds just a few typical western ducks with bright yellow orange legs:
- mallard: But the beak is yellow. Males have black at the tail area, but with white tail feathering, and of course males have distinctively dark green or blue iridescent feathering on the head. In addition, they have a white line above and below iridescent blue feathers on the secondary wing feathers. There is no blue visible here.
- gadwall: Black rump and white wing patch. Male has black beak in breeding coloring. But the book notes "puffy head" on the breeding male and darker gray chest feathering. Hmm.
- northern shoveler: Male has a black beak in breeding colors, but both the male and female have large wide beaks–hence the name "shoveler." The beak is longer than the length of the duck's head. In his breeding colors the male is high contrast with a black iridescent-green head, yellow eye, white chest, back and reddish brown flanks. No white wing patch, but there is a thin "bar" of white.
While everything isn't perfect, it's pretty clear that the ducks we're looking at are two pairs of gadwalls. The males have yet to completely don their breeding plumage, but they aren't mallards or shovelers.
Don't be afraid to try and identify the birds you see. Note the visual or behavioral characteristics that stand out. Those bright yellow-orange legs or a white wing patch can be the key to ruling out other species.
Other Bird Identifications: