Published March 19, 2022, in the McAllen Monitor.
Story and photos by Anita Westervelt, Texas Master Naturalist, South Texas Border Chapter
The curve-billed thrashers are pairing up even though the March weather doesn’t seem to be warming up. Curve-billed thrashers are a fun species to observe. For the most part, they are skittish and generally noticed only when catapulting off the ground in a short flight to safety on a nearby perch. That activity, seen often enough, is a clue to their preferred foraging ground – which happens to be the ground.
Male and female curve-billed thrashers look alike. They are a grey-brown and often mistaken for their cousin, the mockingbird; once perched, curve-billed thrashers are easily identified by their spotted breast and orange eye color.
Another distinguishing feature is their long, slightly downward curved bill, which is designed for searching for food by digging vigorously into the ground, plucking prey from grass and plants, and turning over rocks, leaf-litter and other debris to find beetles, bugs, slugs, snails and insect larva. They are omnivores; their diet also includes moths, butterflies, ants, wasps, centipedes, seeds, vegetation and fruits of hackberry and anacua trees and prickly pear cactus.
Curve-billed thrashers are residents of the Rio Grande Valley and western third of the state up to the Oklahoma panhandle, as well as in New Mexico and northern Mexico. They are nonmigratory. In the Valley, they can be found in thorn scrub and edges of riparian woodlands. They also inhabit residential neighborhoods supported by native vegetation.
The curve-billed thrasher breeding season is somewhat dependent on temperature and rainfall and generally picks up in March but can be as early as February. To attract a female, the male of the species does most of the singing and it’s a clear, lengthy, lyrical tune. They have a variety of songs, and their singing may extend into July.
Once mated, curve-billed thrashers are monogamous and stay paired for several years. Both sexes are involved in nest building and are likely to build in conspicuous locations from two to 20 feet off the ground. They favor native trees that provide dense canopy cover, like mesquite, colima, ebony, sugar and spiny hackberry, blackbrush, huisache, coma and the nonnative but popular live oak.
Nest building can take as little as three days or up to four weeks. They are loosely built structures of sticks and may be cup-shaped or relatively flat with only a depression for the eggs. The nests are lined with soft materials like grasses, feathers or down.
The female will lay between two and five eggs. Both sexes incubate the eggs for 12 to 18 days. They may have two to three broods a year if conditions are favorable and ample food is available. Once the eggs hatch, the female is mostly responsible for feeding the chicks a diet of grasshoppers, beetles, insects and ripe berries. The baby birds fledge after about two weeks.
Curve-billed thrashers are easy to entice with the right food. They will come to platform feeders or to food spread on the ground where they have been observed. Recommended food is hulled sunflower seeds, cracked corn, millet and milo.
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Sources helpful in writing this article include All About Birds, Tamu.edu, Cornell Lab or Ornithology, Wikipedia.org, Audubon.org and Smithsonian Handbooks, “Birds of Texas,” Fred J. Alsop III, DK Publishing, Inc.