Black-necked Stilt Life History

Habitat

Habitat MarshesBlack-necked Stilts inhabit shallow wetlands from the western United States to Central America and parts of South America. In the United States, Black-necked Stilts are commonly found in salt ponds, flooded lowlands, or shallow lagoons. Human-maintained wetlands such as sewage ponds or flooded pastures are particularly suitable habitats for these birds, since such environments have some sparse vegetation without being too overgrown. The endangered Hawaiian subspecies, the Ae'o, lives in wetlands, mudflats, and ponds on all the major islands.Back to top

Food

Food Aquatic invertebratesBlack-necked Stilts wade in shallow waters to capture their meals of aquatic invertebrates and fish. They often consume such fare as crawfish, brine flies, brine shrimp, beetles, water boatmen, and tadpoles. They peck, snatch, and plunge their heads into the water in pursuit of their food, and will herd fish into shallow waters to trap them there.Back to top

Nesting

Nest Placement

Nest GroundBlack-necked Stilts nest on the ground. They tend to build on surfaces above water, such as small islands, clumps of vegetation, or even, occasionally, floating mats of algae. Both female and male Black-necked Stilt choose the site; they look for places with soft substrate that can be scraped away to form the depression in which they nest.

Nest Description

Male and female Black-necked Stilts trade off the job of constructing the nest. While one mate observes, the other scrapes into the dirt with breast and feet to form a depression about 2 inches deep. As they dig, they throw small bits of lining over their back into the nest. Most lining is added to the nest during incubation, and consists of whatever material is closest to the nest, including grasses, shells, mud chips, pebbles, and bones. Some nests are left unlined.

Nesting Facts
Clutch Size:1-5 eggs
Number of Broods:1 brood
Egg Length:1.5-2.0 in (3.7-5.1 cm)
Egg Width:1.0-1.4 in (2.6-3.6 cm)
Incubation Period:21-26 days
Egg Description:Olive-gray with brown speckles.
Condition at Hatching:Down-covered, alert, able to leave the nest within about 2 hours of hatching.
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Behavior

Behavior ProbingBlack-necked Stilts wade for their food, and will only swim or dive when under duress. During breeding and during winter, they are strongly territorial birds, and are particularly aggressive to chicks that are not their own. When not breeding, Black-necked Stilts roost and forage in closely packed groups, often staying within a foot of each other. Black-necked Stilts are semicolonial when nesting, and they participate en masse in anti-predator displays. The displays include one in which nonincubating birds fly up to mob predators, and one in which all birds encircle a predator, hop up and down, and flap their wings.Back to top

Conservation

Conservation Low ConcernBlack-necked Stilt populations appear stable and increased between 1966 and 2014 in the continental U.S., according to the North American Breeding Bird Survey. However, the Hawaiian subspecies, the Ae'o (Himantopus mexicanus knudseni), is a federally endangered species and is on the 2014 State of the Birds Watch List, which lists bird species that are at risk of becoming threatened or endangered without conservation action. Ae'o numbers have risen slowly in the last 30 years, but there are still under 2,000 individual breeding birds. Because stilts are wetland birds they are vulnerable to polluted runoff including pesticides and especially selenium. Stilts are sometimes monitored as indicators of contaminated irrigation water in the environment at large. In Hawaii, invasive aquatic plants deprive stilts of open water and mudflats. In the nineteenth century stilts were hunted throughout their range.Back to top

Credits

Lutmerding, J. A. and A. S. Love. Longevity records of North American birds. Version 2015.2. Patuxent Wildlife Research Center, Bird Banding Laboratory 2015.

North American Bird Conservation Initiative. 2014. The State of the Birds 2014 Report. US Department of Interior, Washington, DC, USA.

Robinson, Julie A., J. Michael Reed, Joseph P. Skorupa and Lewis W. Oring. 1999. Black-necked Stilt (Himantopus mexicanus), version 2.0. In The Birds of North America (P. G. Rodewald, editor). Cornell Lab of Ornithology, Ithaca, New York, USA.

Sauer, J. R., J. E. Hines, J. E. Fallon, K. L. Pardieck, Jr. Ziolkowski, D. J. and W. A. Link. The North American Breeding Bird Survey, results and analysis 1966-2013 (Version 1.30.15). USGS Patuxtent Wildlife Research Center 2014b. Available from http://www.mbr-pwrc.usgs.gov/bbs/.

Sibley, D. A. (2014). The Sibley guide to birds, second edition. Alfred A. Knopf, New York, USA.

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