Mistaken expectations

Red-necked phalaropes (Phalaropus lobatus) foraging at twilight.

Phalaropus lobatus
Photo: Max Odland

Walking next to the water just south of Seward one evening, I came across an odd sight. Bobbing in the failing light were two little birds that swam slow circles, wiggling their heads back and forth all the while. Nothing too unusual about that… birds swim in the water all the time. But these particular birds were distinctly sandpiper-shaped. This amateur birder is used to seeing sandpipers act a little more like this.

A little research revealed them to be phalaropes, a genus of shorebirds that often take to the water (other sandpipers rarely do). Specifically, these two peculiar head-wigglers are juvenile red-necked phalaropes. Despite their odd movement style, these birds actually behaved quite gracefully on the water. They swim about looking for small pieces of food on the surface of the water, and even swim in small circles to create an upwelling current that brings more bits to the surface.

Phalaropes go above and beyond when it comes to defying expectations. Not only do they take to the water where their relatives prefer the shore, they reverse the sex roles found in most other birds. Usually it’s the male birds that have brighter feathers, spend time defending territories, and compete over females.

In red-necked phalaropes, however, the story has a distinct twist. Females compete over available males, mate, and leave a clutch of eggs in the care of said males, who proceed to take over parental duties (i.e. incubate the eggs and raising the chicks). The females, meanwhile, get busy trying to find another male and repeat the process.

What causes such a reversal in the usual roles? It all comes down to investment. The parent that invests the most resources in their young is the one that gets to be choosy. It takes a male longer to incubate a clutch of eggs than it takes a female to lay one. The male’s time is the limiting factor in making baby phalaropes, ergo females compete for males. Interestingly, when a nest fails (as nests often do), males usually try to mate again with the same female, and reduce the chances that they’ll spend valuable time and energy raising a clutch fertilized by another male.

smart little guys.

When you see something unexpected, you have three basic options: 1) think, ‘huh, that’s funny,’ and go on your way; 2) reject it offhand with a, ‘that can’t be right,’; or 3) dig deeper and see what you can find out about it. I’m a big fan of option 3… You never know what other surprises are waiting for you.

2 responses to “Mistaken expectations

  1. Pingback: Rare birds in Spain | Dear Kitty. Some blog·

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