Killdeer
Scientific Name: Charadrius vociferus. The word “vociferus” comes from the Latin vox meaning “voice” and ferre meaning “to carry.” The name refers to the killdeer’s vocal nature; it often is heard vociferously calling its common name (kil-dee).
Description: The killdeer is the largest of the ringed plovers (a plover is a type of shorebird). A lanky bird (8 inches to 11 inches in length), the killdeer has long legs; long, slender wings; and an especially long tail. When it flies, its rufous rump and upper tail coverts and broad white wing stripes are conspicuous. Sexes look alike. The two black bands running horizontally across the killdeer’s white breast are characteristic of the species. The bands act as a type of camouflage known as “disruptive coloration.” These bands form a pattern that breaks up the outline of the body, visually disrupting potential predators. It is thought that the adult killdeer has two breast bands — rather than the typical one seen in smaller plovers — because band size cannot increase in proportion to body size and still serve a disruptive function. This may be why downy killdeer chicks have only one breast band.
Distribution: The killdeer is the most widespread plover breeding in North America. Isolated breeding populations also are found in Central America, South America and the Caribbean. Not all killdeer migrate (and those that do, travel only a medium distance) so Arizona has both migratory and resident killdeer populations. Wintering birds are located primarily in lower elevations in southern and western Arizona, while breeding individuals (common and conspicuous statewide) nest in a wide range of elevations and habitat types.
Habitat: Like other plovers, the killdeer nests along sandbars, mud flats and riverbanks of perennial waterways. It also tolerates — and even can thrive in — human-modified habitats away from major water sources. For example, the killdeer is known to frequent airports, athletic fields, golf courses, plowed fields, gravel rooftops and gravel parking lots.
Biology: After migrating in early spring (beginning in February in Arizona), killdeer form pairs soon after arriving on the breeding grounds. Pairs synchronize their reproductive cycles by engaging in a ritualized nest-scraping ceremony. Each bird tosses material over its shoulders and displaces the other bird in a depression it scrapes with its feet. After several scrapes are made within seven to 10 days, the female lays typically four eggs in one of the scrapes. Both sexes incubate the eggs (the male usually incubates at night) for 24 to 28 days. Two days before they hatch, chicks can be heard peeping, possibly to synchronize their hatching. Young are “precocial” (hatching with open eyes and downy feathers) and can run and feed themselves after their down dries (anywhere from an hour to one day). They are completely independent in 20 to 31 days. The killdeer is well-known for aggressive defense of nests and young. It is notorious for distracting potential nest predators by feigning injury to a wing. Killdeer also “false brood” (pretend to incubate unoccupied nearby scrapes), and charge at intruders. Opportunistic foragers, killdeer primarily eat terrestrial invertebrates (earthworms, grasshoppers, beetles and snails), but also will eat small vertebrates and seeds. When searching for food, the killdeer can be seen running, stopping, bobbing and stirring its feet.
Status: Because it tolerates human-modified habitats and activity, the killdeer is one of the most successful shorebirds in North America. However, breeding bird surveys indicate recent declines in some Western states and Canada.
Management Needs: The killdeer does not require conservation assistance. However, because of its close association with humans, the killdeer is vulnerable to pesticide poisoning and collisions with towers, tall buildings and vehicles. Lawn mowers, road graders and domestic animals (dogs and cats) — as well as a host of native reptilian, avian and mammalian predators — can destroy nests. Nest enclosures have been shown to reduce predation by some nest predators.
- By Allen Graber
Wildlife Field Notes - Killdeer