The Black-necked Stilt Himantopus mexicanus
by Juanita N. Baker, Ph.D.
Father stands vigilant, ready for action, to protect his young downy chick who cautiously explores the limits of the mud flat. Parents peck, jab, or sweep with their slightly recurved bills to plunge under water and, probe through mud to snatch aquatic invertebrates, fishes, and insects to eat for themselves or to feed their young. Stilts choose to nest in wetlands with emergent vegetation—plants that have long roots and stems to be able to survive varying water levels along shorelines, mud flats, and human-made evaporation ponds and storm-water treatment facilities. Aquatic plants (like Sesbanias, water lilies) provide some cover for the young, as well as attracting insects and aquatic organisms that feed on the plant’s roots and shoots.
Canal waters and runoff from agricultural lands and yards contain high levels of phosphorous and nitrogen from fertilizers. Those chemicals enter the storm-water facilities and constructed wetlands where they are removed (‘eaten’) by the algae and plants grown for that purpose. Cleaner water then is passed on to our Lagoon. California studies document that cumulative effects of contaminants, such as selenium, may impact chick growth and survivability.
eBird data show that at the end of September, all stilts leave Indian River County for Central and South America for the winter. In January and February, they begin migrating back, most returning by March. In May they’ve selected their breeding sites…not nesting closely together, but each nest on the mudflats at 10-15’ apart, staking out their own territories which the females defend strongly. So, now in September, that young chick will have grown almost as big as Dad, but characteristic of all juveniles, with brown instead of black feathers, and soon ready to leave on its long, hazardous migratory route south, too!
Reference: Robinson, Julie A., J. Michael Reed, Joseph P. Skorupa and Lewis W. Oring. 1999. Black-necked Stilt (Himantopus mexicanus), The Birds of North America Online (A. Poole, Ed.). Ithaca: Cornell Lab of Ornithology; Retrieved from the Birds of North America Online: http://bna.birds.cornell.edu/bna/species/449