Eastern Dakotas Ground Crew Getting Started, with Some Notes on Shorebird Sex

Written by Pam Garrettson and Chris Nicolai
Sunday, May 08, 2011

Pam Garrettson.We have completed our two southernmost air-ground segments, located in southern South Dakota. Although the nearby James River is at flood stage, those air-ground segments typically don’t hold too much water. The timing of spring seems a bit late; we haven’t seen too many lone males that would indicate that females are nesting or incubating. Moreover, we haven’t yet seen many gadwall and ruddy ducks, the latest nesters in the Eastern Dakotas. However, shorebirds, both migrants and area breeders, are abundant, foraging in wet fields and mudflats.

Wilson’s phalaropes breed throughout the prairie pothole region, and are notable because they are one of the few polyandrous birds in the world. That is, the female breeds with several males. Her males build their own nests, the female lays eggs in each one, and the male incubates them and provides all the care for the young. Most birds are monogamous, some are polygynous (a single male breeding with many females), and when the plumage of the sexes differs, typically the male is more brightly colored. By contrast, Wilson’s phalarope males are dull gray and white, while the females are much more conspicuous.

Mating systems in birds, and in animals generally, are closely linked to the need for parental care. Polygyny can occur when females can be the sole source of care, typically when young, aptly named precocial, are mobile and able to feed themselves shortly after hatch. Many upland game birds, such as grouse and quail, fit this bill, and males are typically brightly ornamented.

Species with young that require a lot of care that can best be provided by both parents tend to be monogamous. This is especially true if young cannot feed themselves and/or food is scarce. Although waterfowl young are precocial, among geese, swans, and South American-breeding ducks, males and females both provide parental care, their plumage is equally drab, and they form pair bonds that last from year to year.

An American avocet forages in a nice wetland.  This species breeds in the Prairie Pothole Region.

An American avocet forages in a nice wetland. This species breeds in the Prairie Pothole Region. Photo by Chris Nicolai, USFWS

Lesser golden plovers migrating through South Dakota.  They winter in southern South America and breed in the North American Arctic.

Lesser golden plovers migrating through South Dakota. They winter in southern South America and breed in the North American Arctic. Photo by Chris Nicolai, USFWS

Wilson's phalaropes, one of the few polyandrous birds in the world.  A male is on the right; the more brightly colored female is on the left.

Wilson's phalaropes, one of the few polyandrous birds in the world. A male is on the right; the more brightly colored female is on the left. Photo by Chris Nicolai, USFWS

A marbled godwit sitting on a fencepost, atypical behavior.  This shorebird breeds in the Prairie Pothole Region.

A marbled godwit sitting on a fencepost, atypical behavior. This shorebird breeds in the Prairie Pothole Region. Photo by Chris Nicolai, USFWS

A blue-winged teal drake takes off while a dowitcher sits tight.

A blue-winged teal drake takes off while a dowitcher sits tight. Photo by Chris Nicolai, USFWS