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Corn crake
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==Behaviour== [[File:Corncrake.jpg|thumb|alt=upstretched head and neck|upright|Adult corn crake camouflaged in a field (Russia, 2006)]] The corn crake is a difficult bird to see in its breeding sites, usually being hidden by vegetation, but will sometimes emerge into the open. Occasionally, individuals may become very trusting; for five consecutive summers, an individual crake on the Scottish island of [[Tiree]] entered a kitchen to feed on scraps, and, in 1999, a wintering [[Barra]] bird would come for poultry feed once the chickens had finished.<ref name="cocker" /> In Africa, it is more secretive than the African crake, and, unlike its relative, it is rarely seen in the open, although it occasionally feeds on tracks or road sides. The corn crake is most active early and late in the day, after heavy rain and during light rain. Its typical flight is weak and fluttering, although less so than that of the African crake. For longer flights, such as migration, it has a steadier, stronger action with legs drawn up. It walks with a high-stepping action, and can run swiftly through grass with its body held horizontal and laterally flattened. It will swim if essential. When flushed by a dog, it will fly less than {{convert|50|m|ft|abbr=on}}, frequently landing behind a bush or thicket, and then crouch on landing. If disturbed in the open, this crake will often run in a crouch for a short distance, with its neck stretched forward, then stand upright to watch the intruder. When captured it may feign death, recovering at once if it sees a way out.<ref name="taylor320" /> The corn crake is solitary on the wintering grounds, where each bird occupies {{convert|4.2|β|4.9|ha|acre|abbr=on}} at one time, although the total area used may be double that, since an individual may move locally due to flooding, plant growth, or grass cutting. Flocks of up to 40 birds may form on migration, sometimes associating with [[common quail]]s. Migration takes place at night, and flocks resting during the day may aggregate to hundreds of birds at favoured sites.<ref name="taylor320" /> The ability to migrate is innate, not learned from adults. Chicks raised from birds kept in captivity for ten generations were able to migrate to Africa and return with similar success to wild-bred young.<ref name="Pain2011" /> ===Breeding=== [[File:Corncrake egg, b.png|upright|thumb|alt=cream-coloured egg with red-brown blotches|Painting of an egg]] [[File:Crex crex MWNH 0070.JPG|thumb|Collection of eggs in [[Museum Wiesbaden]]]] Until 1995, it was assumed that the corn crake is [[monogamy in animals|monogamous]], but it transpires that a male may have a shifting home range, and mate with two or more females, moving on when laying is almost complete. The male's territory can vary from {{convert|3|to|51|ha|acre|abbr=on}}, but averages {{convert|15.7|ha|acre|abbr=on}}. The female has a much smaller range, averaging only {{convert|5.5|ha|acre|abbr=on}}. A male will challenge an intruder by calling with his wings drooped and his head pointing forward. Usually the stranger moves off; if it stays, the two birds square up with heads and necks raised and the wings touching the ground. They then run around giving the growling call and lunging at each other. A real fight may ensue, with the birds leaping at each other and pecking, and sometimes kicking. Females play no part in defending the territory. The female may be offered food by the male during courtship. He has a brief courtship display in which the neck is extended and the head held down, the tail is fanned, and the wings are spread with the tips touching the ground. He will then attempt to approach the female from behind, and then leap on her back to copulate. The nest is typically in grassland, sometimes in safer sites along a hedge, or near an isolated tree or bush, or in overgrown vegetation. Where grass is not tall enough at the start of the season, the first nest may be constructed in herby or marsh vegetation, with the second brood in hay.<ref name="taylor320" /> The second nest may also be at a higher altitude that the first, to take advantage of the later-developing grasses further up a hill.<ref name="BirdLife" /> The nest, well hidden in the grass, is built in a scrape or hollow in the ground. It is made of woven coarse dry grass and other plants, and lined with finer grasses.<ref name="Seebohm" /> Although nest construction is usually described as undertaken by the female,<ref name="BWP" /> a recent aviary study found that in the captive population the male always built the nest.<ref name="graham" /> The nest is {{convert|12|β|15|cm|in|abbr=on}} in diameter and {{convert|3|β|4|cm|in|abbr=on}} deep. The clutch is 6β14, usually 8β12 eggs; these are oval, slightly glossy, creamy or tinted with green, blue or grey, and blotched red-brown. They average {{convert|37|Γ|26|mm|in|abbr=on}} and weigh about {{convert|13|β|16|g|oz|abbr=on}},<ref name="taylor320" /> of which 7% is shell.<ref name="BTO" /> The eggs are laid at daily intervals, but second clutches may sometimes have two eggs added per day. Incubation is by the female only; her tendency to sit tight when disturbed, or wait until the last moment to flee, leads to many deaths during hay-cutting and harvesting. The eggs hatch together after 19β20 days, and the [[precocial]] chicks leave the nest within a day or two. They are fed by the female for three or four days, but can find their own food thereafter. The juveniles fledge after 34β38 days. The second brood is started about 42 days after the first, and the incubation period is slightly shorter at 16β18 days. The grown young may stay with the female until departure for Africa. Nest success in undisturbed sites is high, at 80β90%, but much lower in fertilised meadows and on arable land. The method and timing of mowing is crucial; mechanized mowing can kill 38β95% of chicks in a given site, and losses average 50% of first brood chicks and somewhat less than 40% of second brood chicks.<ref name="taylor320" /> The influence of weather on chick survival is limited; although chick growth is faster in dry or warm weather, the effects are relatively small. Unlike many precocial species, chicks are fed by their mother to a greater or lesser extent until they become independent, and this may cushion them from adverse conditions. The number of live chicks hatched is more important than the weather, with lower survival in large broods.<ref name="tylergreen" /> The annual adult survival rate is under 30%,<ref name="BTO" /><ref name="green" /> although some individuals may live for 5β7 years.<ref name="hume" /> ===Feeding=== The corn crake is [[omnivore|omnivorous]], but mainly feeds on [[invertebrate]]s, including [[earthworm]]s, [[slug]]s and [[snail]]s, spiders, beetles, [[dragonfly|dragonflies]], [[grasshopper]]s and other insects. In the breeding areas, it is a predator of ''[[Sitona]]'' [[weevil]]s, which infest [[legume]] crops.<ref name="taylor320" /> and in the past consumed large amounts of the former grassland pests, [[Tipuloidea|leatherjacket]]s and [[click beetle|wireworm]]s.<ref name="auk49" /> This crake will also eat small frogs and mammals, and plant material including grass seed and cereal grain. Its diet on the wintering grounds is generally similar, but includes locally available items such as [[termite]]s, [[cockroach]]es and [[dung beetle]]s. Food is taken from the ground, low-growing plants and from inside grass tussocks; the crake may search leaf litter with its bill, and run in pursuit of active prey. Hunting is normally in cover, but, particularly in the wintering areas, it will occasionally feed on grassy tracks or dirt roads.<ref name="taylor320" /> Indigestible material is regurgitated as {{convert|1|cm|in|abbr=on}} [[pellet (ornithology)|pellets]].<ref name="BWP" /> Chicks are fed mainly on animal food, and when fully grown they may fly with the parents up to {{convert|6.4|km|mi|abbr=on}} to visit supplementary feeding areas. As with other rails, grit is swallowed to help break up food in the stomach.<ref name="taylor320" /><ref name="taylor39" />
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