The killdeer (Charadrius vociferus) is a medium-sized plover. It is a noisy bird, whose English name comes from its distinctive kill deer cry.
The adult has a brown back and wings, a white belly, and a white breast with two black bands. The rump is tawny orange. The face and cap are brown with a white forehead. The eyering is orange-red. The chicks are patterned almost identically with the adults, and are precocial (able to move around immediately after hatching). The killdeer often uses a "broken-wing act" to distract predators from the nest. It is named onomatopoeically after its call.
Video Killdeer
Etymology and taxonomy
The killdeer was first described as Charadrius vociferus by Carl Linnaeus in the 10th edition of his Systema Naturae. This was based on an account of it by Mark Catesby in his The Natural History of Carolina, Florida and the Bahama Islands, where he gave it the name of the "chattering plover".
The killdeer's binomial name is Charadrius vociferus. The genus name Charadrius is a Late Latin word for a yellowish bird mentioned in the fourth-century Vulgate. It derives from Ancient Greek kharadrios a bird found in ravines and river valleys (kharadra, "ravine"). The specific vociferus is Latin and comes from vox, "cry" and ferre, "to bear".
There are three subspecies of the killdeer, including the nominate:
- C. v. vociferus Linnaeus, 1758 - The nominate subspecies, found in the US (including southeastern Alaska), southern Canada, Mexico, and very locally south to Panama. It winters to northwestern South America.
- C. v. ternominatus Bangs & Kennard, 1920 - This subspecies is found on the Bahamas, the Greater Antilles, and Virgin Islands.
- C. v. peruvianus (Chapman, 1920) - This South American subspecies is found in west Ecuador, Peru, and extreme northwest Chile.
The killdeer's name comes from its frequently heard call.
Maps Killdeer
Description
Adult killdeer range in length from 23-27 cm (9.1-10.6 in) with a wingspan averaging 47 cm (19 in). The largest ringed plover, killdeer weigh 88 g (3.1 oz) on average.
Killdeer have a characteristic large, round head, long tail, long flesh-colored legs, and long wings. The bill is short, dark, and thick. Plumage is brownish-tan on dorsal areas and white on the ventral belly and chest; the neck is also surrounded by a white collar. Two large, dark bands surround the upper breast with an additional band located on the head, spanning both the forehead and the area above the bill and continuing around the back of the head. The tail is brown with a black subterminal band, a white terminal band, and white outer tail feathers. Additional defining plumage characters include a brightly colored red-orange rump that is visible during flight and displays, white wing stripes visible during flight. Appearance does not vary between males and females, although breeding females may have additional brown plumage on the head. Juveniles resemble adults with the exception of buff fringe feathers and the presence of only one neck band
Habitat and distribution
The range of the killdeer spreads across the Western Hemisphere. In the summer, killdeer live as far north as the Canadian provinces of Ontario, British Columbia, Alberta, Saskatchewan, the Yukon and Quebec, as well as the southern parts of the U.S. state of Alaska. Killdeer hold a year-round presence across the southern half of the United States and parts of Peru. The killdeer winters throughout Central America.
During the non-breeding season the killdeer uses coastal wetland and beach habitat, as well as coastal fields. It prefers fields that have less recent precipitation. It almost exclusively forages in fields, especially those with short vegetation and cattle combined with short vegetation or standing water. When breeding, it has a home range of about 6 hectares (15 acres). Those with nests more than 50 metres (160 ft) away from water generally have larger home ranges.
Behaviour
These birds will frequently use a distraction display ("broken-wing act") to distract predators from their nests. This involves the bird walking away from its nesting area holding its wings in a position that simulates an injury, flapping around on the ground emitting a distress call. The predators are then usually attracted to the seemingly easy prey. If the parent sees that a potential predator is not following them, it moves closer and gets louder until it gets the attention of the predator. This is repeated until the predator is far from the nest, and the killdeer suddenly "heals" and flies away.
Breeding
The killdeer likely forms pairs on breeding grounds. Both males and females (although the former more often than the latter) advertise in flight with loud "killdeer" calls, and the former can advertise by standing in a high spot and making the same call. Ground chases occur when a killdeer has been approached multiple times by another killdeer. Males also advertise to females by scraping out a fake nest.
To nest, the killdeer uses open fields or other flat areas with short vegetation (usually below 1 centimetre (0.39 in) tall), including agricultural fields, and meadows. Nesting habitat is characterized as having enough nest materials to form a scrape but otherwise having little or no vegetation. The killdeer frequently nests near the site it nested the previous year. It is likely that the male usually returns to nest in the same area regardless of whether or not it retains the same mate. This does not seem to be true of the female, who does not nest in the same territory if it does not have the same mate. Nests are also sometimes located on rooftops. The nest itself is merely a shallow depression or bowl in the ground, fringed by some stones and blades of grass. It generally chooses to build with white nesting material over darker colours; the function of this is suspected to either help keep the nest cool or to help conceal the nest. In a study of piping plovers, the former function was supported, as nests were 2 to 6 °C (36 to 43 °F) cooler than the surrounding ground. The latter function also had some support, as the plovers generally chose pebbles closer in colour to the eggs, but, nests with higher contrast with the ground suffered more predation. When nesting on rooftops, the eggs may be placed on a flat roof, or in a nest of raised gravel, sometimes lined with white pebbles or pieces of seashells.
The eggs of the killdeer are typically laid from mid March to early June in the southern portions of the range, and from mid April to mid July in the northern parts. In Puerto Rico, and possibility in other Caribbean islands, breeding occurs year round.
The killdeer has a clutch of four to six eggs, buff to beige in colour, with brown markings and black speckles. It is about 38 by 27 millimetres (1.5 by 1.1 in) in size. These eggs are laid at intervals of 24 to 48 hours. When these eggs are being laid, the energy expenditure of both sexes is at its highest; the female needs to produce eggs, whereas the male needs to defend its territory. Both the female and male are closer to the nest site during egg laying and incubation, with the male generally being closer to the nest during all stages of breeding. This latter fact is likely due to the male's increased investment in nest-site defense. Up to five replacement clutches can be laid, and there are occasionally two broods. The eggs are incubated for 22 to 28 days by both the male and the female, with the former typically incubating during the night. The time dedicated to incubation is related to temperature, with one study recording that killdeer incubated eggs 99% of the time when the temperature was about 13 °C (55 °F), 76% of the time when it was around 26 °C (79 °F), and 87% of the time during temperatures of about 35 °C (95 °F). When it is hot (above at least 25 °C (77 °F)), incubation does not take the form of warming the eggs, but instead occurs through the cooling of eggs, generally through shading.
The day after the young hatch, they are led by both parents out of the nest. The family then generally moves to a feeding territory with dense vegetation which the chicks are able to hide under when a predator is near. The chicks are raised, at least in single-brood pairs, by both parents, likely because of the high failure rate of nests and the need for both parents to be present to successfully raise the young. In two parents broods, the young are usually attended by only one parent, generally the female, until about two weeks of age, after which the non-attentive parent occasionally tends the young. Otherwise, the non-attentive parent is generally at least 23 metres (75 ft) away from the chicks. Periods of attentiveness for each parent generally last about one to one hour thirty minutes. This time is mainly spent standing when the chicks are young, with the time dedicated to this decreasing as the chicks get older. When the young are below two weeks of age, the attending adult dedicates little time to foraging. The non-attentive adult defends the young most of the time when they chicks are less than a week old, but this task steadily shifts onto the attentive adult, until about three weeks of age, when the attending parent does almost all of the defense. One parent at a time generally broods the chicks, and does so frequently until they are two days old. They are also brooded, until about 15 days after hatching, during rain, and, until about 18 days after hatching, at night. The only time when the young are not in the presence of a parent is when the parents are responding to a predator or an aggressive conspecific, or when mating.
There are sometimes one parent broods when a pair has two broods. This brood is watched over by the male, who is able to hatch the chicks on its own, unlike the female. In this case, the adult does not spend most of the time standing, and the time it did spend did not decrease as a function of age. Like attentive adults in two parent broods, the sole parent of a brood increases the time spent foraging as the chicks get older.
The young fledge about 31 days after they hatch, and generally move to moister areas in valleys and on the banks of rivers. They may be cared for by their parents for up to 10 days after they fledge, and exceptionally 81 days after hatching.
About 52% to 63% of nests fail to produce any fledged young.
Feeding
The killdeer feeds primarily on insects (especially beetles and flies), in addition to millipedes, worms, snails, spiders, and some seeds. It opportunistically takes tree frogs and dead minnows. It forages almost exclusively in fields (no matter the tide), especially those with cattle and short vegetation or standing water. Standing water alone does not usually have a significant effect on field choice, but when combined with cattle, it does. When feeding in water, it may use "foot-trembling", where it stands on one foot and shakes the other in the water for about five seconds, and then pecks at any prey stirred up by it. When feeding in fields, it may follow ploughs to take earthworms disturbed to the surface.
Predators
Predators to the killdeer include herring gulls, common crows, raccoons, and striped skunks.
Responses to predators
Various methods of distracting predators are employed during the breeding season by parents. During egg-laying, the most common response to predators is to quietly leave the nest. When incubation starts, and as it progresses, the intensity of predator responses increases, peaking just after hatching. This is likely because it is worth more to protect the young at that stage, as they are more likely to survive to fledge. After hatching, though, the intensity of responses decreases, until a normal response is calling at a stand. This is because as the young age, they get more independent.
Gallery
References
External links
- Killdeer at Enature.com - enature.com
- "Killdeer media". Internet Bird Collection.
- Killdeer - Charadrius vociferus - USGS Patuxent Bird Identification InfoCenter
- Killdeer Fact Sheet Hinterland Who's Who - produced by Environment Canada and Canadian Wildlife Federation
- Killdeer Bird Sound at Florida Museum of Natural History
- Killdeer photo gallery at VIREO (Drexel University)
Source of the article : Wikipedia
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