Tuesday, October 22, 2013

American Black Duck at Elk Island National Park

Once again I offer some sketchy video of an uncommon migrant in Central Alberta! The American Black Duck, whose range in Canada is primarily east of Saskatchewan, has been seen less frequently in Alberta in recent decades, mirroring a widespread decline. Only two Alberta occurrences, both from the Calgary area, are documented in eBird.

This individual showed up yesterday, October 21st. While American Black Duck x Mallard intergrades are not unusual, this individual showed no influence of Mallard genes. Note the pure purple speculum (no white border) and similarly a uniformly dark tail.

Helpfully, for comparative purposes, there are much paler female Mallards swimming in and out of frame.

For those birders less familiar with the American Black Duck, here are some distinguishing features:
  • size and structure very similar to the Mallard (distinguishing it from the smaller or less robust Gadwall and American Pintail
  • general colour pattern similar to female Mallard
In contrast to a female Mallard the American Black Duck:
  • has wings and body about four shades darker and shows marked contrast between lighter head/neck and darker body 
  • lacks white border to blue/violet speculum 
  • lacks any white on tail 
  • has a uniformly green or greenish yellow coloured bill.
Here's a typical male Black Duck.
American Black Duck (male), image shared generously under a Creative Commons license by Dick Daniels (http://carolinabirds.org/).

Update: Oct 23.

For the third consecutive morning the ABDU was present in the usual spot at 08:30 am. I tried paddling a canoe closer to get some better photos; however; the waterfowl assemblage was skittish. Here's the only capture I got, showing, at left, the spread wing of departing ABDU.

Update: Oct 25.

Still present at 8:40 am. Some skim ice formed overnight. With colder weather in the forecast, I suspect all waterfowl will leave Astotin Lake in the next few days.

Update: Oct 27.  Present at 11:30 am in the usual spot.

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