Whenever I scan a flock of ducks on open water, I watch for the divers. I try to predict where they'll resurface. I'm usually wrong because I underestimate how long they can hold their breath and how far they can travel underwater.
Here are some of the diving ducks you might encounter while birding wetlands this spring.
Canvasback (2.7 lb.) Dark rusty head, head profile angular, black breast, light-colored back, favors deep water.
Redhead (2.3 lb.) Rusty head, profile of head a bit concave rather than angular, breast black, back gray.
Ring-necked duck (1.5 lb.) Poorly named with a white ring near bill tip; head may appear pointed; gold eye; dark head, breast and back; sides gray.
Scaups Two species, greater (2.3 lb.) and lesser scaup (1.8 lb.). Distinguishing them is an advanced skill, consult a field guide. Both have dark head and breast, gray back and pale sides.
Common goldeneye (1.9 lb.) Dark head with round white cheek patch, gold eye, breast and sides white, cavity nester.
Bufflehead (13 oz.) Small dark head with large white bonnet, white breast and sides, cavity nester.
Mergansers Three species, all have "toothed" bill for catching fish. Common merganser (3.4 lb.) large with green head with red bill, white body, black back, cavity nester. Red-breasted merganser (2.3 lb.) green head with shaggy crest, wide white collar, and streaked rusty breast. Hooded merganser (1.4 lb.) black bill, black crested head, when crest is fanned a large white patch appears, gold eye, chestnut sides, cavity nester.
Ruddy duck (1.2 lb.) Chunky compact duck, tail often cocked upward, head dark with large white cheeks, bill blue, body chestnut.
On a really good day, if you're lucky you might see one of several species of sea ducks on larger lakes or rivers.
Harlequin duck (1.3 lb.) Strikingly marked, body primarily gray and white, chestnut sides visible when on water, conspicuous white markings on face and chest.
White-winged scoter (3.7 lb.) Large, all black with white eye spot and wing patches.
Long-tailed duck (formerly called oldsquaw) (1.6 lb.) Dark with white sides and belly, white patch around eyes, middle part of bill pink, long tail.
Next week: Duck-like waterfowl likely to be seen in Western Pennsylvania.
Scott Shalaway is a biologist and author. His other weekly Post-Gazette column, " GETintoNATURE ," is published in the GETout section, available only in the early Sunday edition sold Saturdays in stores. Shalaway can be reached at http://scottshalaway.googlepages.com and RD 5, Cameron, WV 26033.