Water Rail

Appearance

The adult of the nominate subspecies is a medium-sized rail, 23–28 cm long with a 38–45 cm wingspan. Males typically weigh 114–164 g and females are slightly lighter at 92–107 g.

The upper parts from the forehead to tail are olive-brown with black streaks, especially on the shoulders. The sides of the head and the underparts down to the upper belly are dark slate-blue, except for a blackish area between bill and eye, and brownish sides to the upper breast. The flanks are barred black and white, and the undertail is white with some darker streaks. The long bill and the iris are red, and the legs are flesh-brown. The sexes are similar; although the female averages slightly smaller than the male, with a more slender bill, determining sex through measurements alone is unreliable.

The juvenile has a blackish crown and a white chin and throat. The underparts are buff or white with darker bars, and the flank markings are brown and buff, rather than black and white. The undertail is buff, and the eye, bill and leg colours are duller than the adult. The downy chick is all black apart from a mainly white bill. After breeding, the rail has an extensive moult, and is flightless for about three weeks. Individual adults can be identified by the markings on the undertail, which are unique to each bird. Adult males have the strongest black undertail streaks. It has been suggested that the dark barring on the undertail of this species is a compromise between the signalling function of a pure white undertail, as found in open water or gregarious species like the Common Moorhen, and the need to avoid being too conspicuous.

The Water Rail can readily be distinguished from most other reed bed rails by its white undertail and red bill; the latter is a little longer than the rest of the rail's head and slightly down-curved. The somewhat similar Slaty-breasted Rail of tropical Asia has a stouter bill, a chestnut crown and white-spotted upperparts. Juvenile and freshly moulted Water Rails may show a buff undertail like Spotted Crake, but that species' plumage is spotted with white, and it has a much shorter, mainly yellowish bill. The range of the Water Rail does not overlap with that of any other ''Rallus'' species, but vagrants could be distinguished from their American relatives by the lack of rufous or chestnut on the closed wing. The larger African Rail has unstreaked darker brown upperparts and brighter red legs and feet.

Naming

There are three recognised subspecies.

⤷  ''R. a. aquaticus''. This is the nominate subspecies that breeds in Europe, North Africa, Turkey, western Asia to the Caspian Sea and western Kazakhstan, and in a narrow band east to central Siberia.
⤷  ''R. a. hibernans''. The Icelandic race, which has slightly warmer brown upperparts than the nominate form. The bars of the flanks are dark brown, not black, and the bill is somewhat shorter; the grey of the underparts may have a brown tinge.
⤷  ''R. a. korejewi''. This subspecies breeds in south central Asia from southern and eastern Iran east to western China, and in the Indian subcontinent in Kashmir and Ladakh. It is slightly larger than the nominate race, with paler brown upperparts and slightly paler slate underparts. It has a weak brown stripe through the eye.

Distribution

The Water Rail breeds across temperate Eurasia from Iceland and the British Isles discontinuously to North Africa, Saudi Arabia and western China. Its distribution in Asia is poorly studied.

Status

The Water Rail's numbers are declining, but it has a large population of 100,000–1,000,000 adults and a huge breeding range estimated at 15,600,000 km2; it is therefore classed as Least Concern on the IUCN Red List.

Behavior

This rail is a skulking species, its streaked plumage making it difficult to see in its wetland habitat. Its laterally compressed body allows it to slip though the densest vegetation, and it will "freeze" if surprised in the open. It walks with a high-stepping gait, although it adopts a crouch when it runs for cover. It swims, when necessary, with the jerky motion typical of rails, and it flies short distances low over the reeds with its long legs dangling. Although their flight looks weak, Water Rails are capable of long sustained flights during their nocturnal migrations, and are sometimes killed in collisions with lighthouses or wires. British-ringed birds have been recovered from as far away as Poland, Czechoslovakia and Sweden.

This species defends its breeding and wintering territories. Birds will charge each other with neck outstretched when breeding, sometimes both members of a pair attacking together. Large strongly-marked males are dominant in winter, when the direct aggression is replaced by sharming while standing upright on tip-toe, head jerking and bill thrusting.

Habitat

The breeding habitat of the Water Rail is permanent wetland with still or slow-moving fresh or brackish water and dense, tall vegetation, which may include common reed, reedmace, irises, bur-reed or sedges. In coastal areas, sea rush is common in saltmarsh breeding sites, with sedges and bur-reed dominant in somewhat less saline environments. A study in The Netherlands and Spain showed that the rush provided better concealment than the other maritime plants. As elsewhere, nests were constructed from the nearest available plants. Where it occurs, saw-sedge provides good breeding habitat, its tall dense structure providing good cover for the nesting rails.

The preferred habitat is ''Phragmites'' reedbed with the plants standing in water, with a depth of 5–30 cm, muddy areas for feeding and a rich diversity of invertebrate species. Locations with nearby willows or shrubs are favoured above large areas of uniform habitat. In addition to natural fresh or marine marshes, this rail may use gravel or clay excavations and peat workings as long as there is suitable habitat with good cover. It may be found in rice paddies or on floating islands, and it occurs in Kashmir in flooded sugarcane fields. A Finnish study showed that the main factor influencing the distribution of Water Rails was the extent of vegetation cover, with the highest densities in the most vegetated areas; the presence of other marshes nearby was also significant. However, factors such as temperature, rainfall, length of shore line and extent of peat, important for some other marsh birds, were not statistically relevant. The areas with the highest densities of the rail also had the greatest numbers of three species considered at risk in Finland, the Great Reed Warbler, Eurasian Bittern and Marsh Harrier. The northern limit of breeding seems to be determined by the transition from nutrient-rich wetland to poorer, more acidic water. This leads to the replacement of common reed by a more open vegetation type dominated by marsh cinquefoil, which is unsuitable for the rails.

Reproduction

The Water Rail is monogamous and highly territorial when breeding. The birds pair off after arriving at their nesting areas, or possibly even before spring migration. In large wetlands with good conditions birds may nest 20–50 m apart. Territories vary in size, but 300 m2 is typical. The pair give courting and contact calls throughout the breeding season. The male selects the nest site which he shows to the female while posturing with raised back feathers, wings arched over his back, tail spread and bill pointed vertically downwards. This display is accompanied by a loud call. Before mating, he raises his wings and tail, and bows with his bill touching his breast. The male feeds the female during courtship, and, when incubating, she may leave the nest to display to the male, walking round him, calling softly, rubbing her bill against his and taking short runs to and from him.

The nest is made from whatever wetland vegetation is available and built mostly by the male, usually in a single day. It is raised 15 cm or more above the level of the marsh, and is sometimes constructed on clumps of roots, tree stumps or similar support. It may be built up higher if the marsh waters start to rise. The nest is 13–16 cm across and about 7 cm. It is well hidden and approached cautiously by narrow tracks.

The typical clutch is 6–11 eggs across most of the range, but appears to be smaller in Kashmir at around 1,500 m altitude. Laying dates vary with location, from late March in western Europe and North Africa, to late May in Kashmir and June in Iceland. The clutch size may be smaller early or late in the breeding season. The breeding season can be extended by replacement and second clutches. The eggs are blunt and oval, smooth and slightly glossy; the colour varies from off-white to pink-buff, with reddish-brown blotches mainly at the broader end that sometimes merging into a single patch. Variation in egg size across the four subspecies is much less than differences between individual eggs; the average size of the eggs of the nominate subspecies, 36 × 26 mm, is therefore typical for the species as a whole. The eggs weigh about 13 g , of which 7% is shell.

Both parents incubate the eggs, although the female takes the larger share of this duty. The eggs are incubated for 19–22 days to hatching, with at least 87% success. Food is brought to the nest by the other adult and passed to the sitting parent who feeds the chicks. The precocial, downy young leave the nest within two days of hatching but continue to be fed by their parents, although the chicks also find some of their own food after about five days. They are independent of their parents after 20–30 days and can fly when aged 7–9 weeks. If a nest appears to have been discovered, the female may carry the chicks or eggs one by one to another location; the eggs are carried in the bill, but small chicks may be tucked under the wing. Sitting birds may stay on the eggs even when approached closely, or attack the intruder, or feign injury as a distraction. The Water Rail can breed after its first year, and it normally raises two broods.

Average survival after fledging has been estimated as between 17 and 20 months, with an annual survival rate slightly less than 50% per year for the first three years, and somewhat higher thereafter. The maximum recorded age is 8 years 10 months.

Food

Water Rails are omnivorous, although they mainly feed on animals. These include leeches, worms, gastropods, small crustaceans, spiders, and a wide range of both terrestrial and aquatic insects and their larvae. Small vertebrates such as amphibians, fish, birds and mammals may be killed or eaten as carrion. Vertebrates are impaled with a strike of the bill which breaks the prey's spinal cord.

Plant food, which is consumed more in autumn and winter, includes the buds, flowers, shoots and seeds of water plants, berries and fruit. In south Asia, paddy may sometimes be eaten. The young rails are fed mainly on insects and spiders. Food obtained on land or from mud is normally washed in water before it is eaten. After rain, rails may probe soft ground for earthworms. This species will occasionally feed in the open even when not forced to do so by cold weather; Edmund Meade-Waldo described seven rails feeding in an open meadow. Despite its skulking nature, the water Rail appears to thrive in captivity when fed on animal food such as raw meat or earthworms; one individual was taught to jump for worms suspended from a fishing rod.

Predators

Predators of the Water Rail include a number of mammals and large birds. The American mink was partly responsible for the extinction of the Icelandic population, and cats and dogs have also been recorded as killing this species. At least locally, otters will also eat rails and other water birds. The Eurasian Bittern, another reed bed bird, will consume rails, as will Grey Herons. Water Rails are particularly vulnerable to the heron when forced out of the cover of the reeds by very high tides. Wetland-hunting harriers are predictable predators, but more unusually, the rail has also been recorded as a prey item of the Tawny Owl, Short-eared Owl, Eurasian Eagle-Owl, Greater Spotted Eagle, Common Kestrel, and night-hunting Peregrine Falcons.