Clowns on the water

Another day down at Starved Rock watching eagles, so here's a shot from last fall:

Harlequin Duck (Histrionicus histrionicus),
Waukegan Beach, Lake Co, IL 11/16/2013

This female Harlequin Duck spent several days in the area, then moved on to who-knows-where. As you can see, they prefer to be in amongst the breaking waves, where they can dive to find their preferred foods, primarily small mussels. (Those would be Zebra Mussels here in Illinois -- a subject for a warmer day.) During the breeding season, they live on rivers, primarily fast-flowing ones in Alaska, British Columbia, and the pacific northwest. There is a smaller population in eastern Canada, where our Chicago birds probably come from, and they occur in Iceland and parts of northern Eurasia as well.

Here's a shot from Alaska, of a female just north of Nome, in her preferred breeding habitat. Given the date, she's probably on her way out to the coast and thence down to the Aleutians.

Harlequin Duck, north of Nome, AK, 8/10/2012

Males are impressive birds, but unfortunately, this is the only decent shot I have of one, from the Cincinnati Zoo:

Harlequin Ducks, female and male, Cincinnati Zoo, 3/29/2012

Google them for a real treat.

These guys have some interesting breeding strategies -- males and females pair up on the winter grounds, like many ducks, but unlike most ducks, Harlequins form long-term pair bonds. (1) The bond only goes so far, though. Once the female is done laying eggs, the male heads right back down to the ocean. This can be a problem for conservationists, since that means females only have the opportunity to lay one clutch, and if it fails, the entire season is a loss.

But how do they maintain long-term pair bonds if the males don't stick around? Well, both males and females show a high degree of winter philopatry (i.e. they keep going back to the same winter locations). (2) So the males and females end up finding each other again each winter. Even males without a mate return to the same place initially, although they may then move on. Most ducks, in contrast, only pair for one season, and males will follow females back to wherever the females hatched. (3)

This difference has interesting implications for differences in population structures, but that's a topic for another week.

 

 

(1) Smith, C. M., Cooke, F., Robertson, G. J., Goudie, R. I., & Boyd, W. S. (2000). Long-term pair bonds in Harlequin Ducks. The Condor, 102(1), 201-205.

 

(2) Robertson, G. J., Cooke, F., Ian Goudie, R., & Sean Boyd, W. (2000). Spacing patterns, mating systems, and winter philopatry in Harlequin Ducks. The Auk, 117(2), 299-307.

 

(3) Rohwer, F. C., & Anderson, M. G. (1988). Female-biased philopatry, monogamy, and the timing of pair formation in migratory waterfowl. In Current ornithology (pp. 187-221). Springer US.