Find out all about the raptor, also known as Rallus aquaticus

The rail rail (Rallus aquaticus) is a bird of the rail family that breeds in well-vegetated wetlands in Europe, Asia and North Africa. Northern and eastern populations are migratory, but this species is a permanent resident in the warmer parts of its breeding range.

Summary

The adult is 23-28 cm (9-11 inches) long and, like other rails, has a laterally flattened body, which allows it easier passage through the reed beds it inhabits. It has mainly brown upperparts and blue-grayish underparts, black impeding the flanks, long toes, a short tail and a long reddish bill.

Immature birds are generally similar in appearance to adults, but the blue-gray in the plumage is replaced by buff. The downy chicks are black, as with all rails. The former subspecies R. indicus, has distinctive markings and a call that is very different from the pig-like squeak of western breeds, and is now usually divided as a separate species, the brown-cheeked rail.

The rail breeds in reedbeds and other marshy sites with tall, dense vegetation, building its nest a little above the water level from any available plants nearby. The whitish, spotted eggs are incubated mainly by the female, and the precocially downy chicks hatch in 19-22 days. The female will defend her eggs and brood against intruders, or move them elsewhere if discovered.

This species can reproduce after its first year, and normally raises two clutches each season. The raccoons are omnivorous, feeding mainly on invertebrates during the summer and on berries or plant stems in the winter. They are territorial even after breeding, and will aggressively defend feeding grounds in winter.

These raccoons are vulnerable to flooding or freezing conditions, habitat loss, and predation by mammals and large birds. The introduced American mink has exterminated some island populations, but overall its huge range and large numbers mean that it is not considered threatened.

Taxonomy

The razorbills are a family of birds comprising about 150 species. Although the origins of the group are lost in antiquity, the largest number of species and the most primitive forms are found in the Old World, suggesting that this family originated there. However, the genus Rallus, the group of long-billed reed specialists to which the water rail belongs, arose in the New World. Its Old World members, the water, African and Malagasy rails, form a superspecies, and are thought to have evolved from a single invasion from across the Atlantic.

Genetic evidence suggests that the aquatic rail is the most closely related of its genus to the Pacific Gallirallus rails, and is basal to that group. The aquatic rail was first described by Linnaeus in his Systema Naturae in 1758 under its current scientific name, Rallus aquaticus. The binomial name is the Latin equivalent of the English word “water rail”.

The former subspecies R. a. indicus has vocalizations very different from those of the rail, and was considered a separate species in early work. It was restored as a full species R. indicus, by Pamela Rasmussen in her Birds of South Asia (2005). Her treatment has gained acceptance, and is followed in Birds of Malaysia and Singapore (2010). A 2010 study on molecular phylogeny further supported the possibility of a specific status for R. indicus, which is estimated to have diverged from western forms about 534,000 years ago.

Fossils

The oldest known fossils of an ancestral waterway are Carpathian bones dating from the Pliocene (1.8-5.3 million years ago). By the end of the Pleistocene, two million years ago, fossil evidence suggests that the raccoon was present throughout most of its present range. This species is well recorded, with more than 30 records from Bulgaria alone, and many others from throughout southern Europe and China.

An Eivissa rail, Rallus eivissensis, was smaller but more robust than the waterway, and probably had less flight capacity. In the Quaternary, the island lacked terrestrial mammals, and this distinctive form presumably descended from its continental relative. It became extinct at about the same time as human arrival on the island, between 16,700 and 5,300 BC. The named race of the river railroad is nowadays very rare in Eivissa.

Description of the rascón

The adult of the nominate subspecies is a medium-sized raptor 23-28 cm (9.1-11.0 in) long with a wingspan of 38-45 cm (15-18 in). Males typically weigh 114-164 g (4.0-5.8 oz) and females are slightly lighter at 92-107 g (3.2-3.8 oz). The upper parts, from forehead to tail, are olive-brown with black streaks, especially on the shoulders. The sides of the head and the underparts to the top of the belly are dark slate blue, except for a blackish area between the beak and eye, and the brownish sides of the upper breast.

The flanks are striped black and white, and the underside of the tail is white with some darker streaks. The long bill and iris are red, and the legs are flesh brown. Sexes are similar; although female averages slightly smaller than males, with a thinner bill, sex determination by measurements alone is not reliable.

The juvenile has a blackish crown and a white chin and throat. The underparts are smooth or white with darker bars, and the flank markings are brown and smooth, rather than black and white. The undertail is buff, and the eye, bill and leg colors are duller than those of the adult. The downy chick is all black, apart from a mostly white bill. After breeding, the razorbill has an extensive molt, and is flightless for about three weeks.

Individual adults can be identified by the markings on the underside of the tail, which are unique to each bird. Adult males have the strongest black lower streaks. It has been suggested that the dark lower tail ban of this species is a compromise between the signaling function of a pure white lower tail, as found in open water or gregarious species such as the common moorhen, and the need to avoid being too conspicuous.

The rail rail can be easily distinguished from most other rail rails by its white tail and red bill; the latter is slightly longer than the rest of the rail’s head (55-58% of the total) and slightly curved downward. The somewhat similar slate rail from tropical Asia has a stronger bill, a chestnut crown and white-stained upperparts.

The range of the water rail does not coincide 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 dark brown unstriped upperparts and brighter red legs and feet. The larger African rail has dark brown upperparts without stripes and brighter red legs and feet.

Vocalizations

The water rail is a vocal species that gives its main call, known as “sharming”, throughout the year. It is a series of grunts followed by a high-pitched piglet-like squeal that ends in more grunts. It is used as a territorial call, alarm and announcement. Members of a pair may alternately call the male giving lower and slower notes than their mate.

The courtship song, given by both sexes, is a tyick-tyick-tyick that often ends with a trill by the female; the male may sing for hours. The flight call is a high-pitched whistle, and other vocalizations include a repeated, loud rustle given by the male when showing the nest site to the female, and a purr given by both parents when in the nest with the chicks. The rails are most vocal when a territory is established and at the beginning of the breeding season, when calling may continue at night. Initially, chicks whine weakly, but soon develop a begging call.

When the researchers played recordings of the warbler at night to attract that species for trapping, they found rails and other wetland birds were also anchored, despite the lack of suitable habitat, suggesting that rails and other nocturnal migrants recognized the warbler’s song and associated it with the marshy habitat in which it is normally found. (See Article: Scavenging Birds)

Subspecies

There are three recognized subspecies:

  • R. a. aquaticus (Linnaeus, 1758). 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 eastward to central Siberia.
  • R. a. hibernans (Salomonsen, 1931). The Icelandic breed, which has slightly warmer brownish upper parts than the nominate form. The flank bars are dark brown, not black, and the bill is somewhat shorter; the gray underparts may have a brown tinge.
  • R. a. korejewi (Zarudny, 1905) (includes the dubious forms deserticolor, tsaidamensis and arjanicus). This subspecies breeds in southern central Asia, from southern and eastern Iran to eastern China (sometimes in Beijing, Shanghai, etc.), and on the Indian subcontinent in Kashmir and Ladakh. It is slightly larger than the nominate breed, with paler brown uppers and slightly paler slate underparts. It has a faint brown stripe across the eye.

The differences between the other three races appear to be clinal, and it is possible that they all merge into R. a. aquaticus.

Distribution and habitat

The raccoon crosses temperate Eurasia from Iceland and the British Isles discontinuously to North Africa, Saudi Arabia and western China. Its distribution in Asia is poorly studied. The Icelandic population of the skink, R. a. hibernans, became extinct around 1965, as a result of habitat loss due to wetland drainage and predation by introduced American mink.

Prior to its extinction, at least some birds were present year-round on the island, depending on the warm volcanic springs to survive during the colder months, but this race was also found in winter on the Faroe Islands and Ireland, and passing through the Western Isles, suggesting that the Icelandic form was a partial migration. The nominate subspecies, R. a. aquaticus, resides in the milder south and west of its range, but migrates southward from areas that are subject to harsh winters.

Winters within its breeding range, and also further south in North Africa, the Middle East and the Caspian Sea area.The peak migration period is from September to October, with most birds returning to the breeding grounds from March to mid-April. A specimen from the nominated population labeled “Baluchistan” and collected by Richard Meinertzhagen is considered of dubious provenance. R. a. korejewi is another partial migrant, with part of the population wintering from Iraq and eastern Saudi Arabia eastward through Pakistan and northern India to western China.

The breeding habitat of the razorbill is a permanent wetland with slow or still moving fresh or brackish water and dense, tall vegetation, which may include common reed, reed canary grass, lily pads, burros, or sedges. In coastal areas, sea fever is common in salt marsh breeding sites, where sedges and cattails predominate in somewhat less saline environments. A study in the Netherlands and Spain showed that rush provided better concealment than other maritime plants.

As elsewhere, nests were built with the nearest available plants. Where it occurs, saw-edge provides good breeding habitat, its dense 1.5 m high structure providing good cover for nesting rails. The preferred habitat is Phragmites reedbed with plants in the water, with a depth of 5-30 cm (2.0-11.8 in), muddy feeding areas and a rich diversity of invertebrate species.

Locations with nearby willows or shrubs are preferred over large areas of uniform habitat. In addition to natural fresh or marine marshes, this rail may use gravel or clay excavations and peat works provided there is suitable habitat with good cover. It can be found in rice paddies or on floating islands, and is found in Kashmir in flooded sugarcane fields.

A Finnish study showed that the main factor influencing the distribution of waterways is the extent of vegetation cover, with the highest densities in the most vegetated areas; the presence of other nearby marshes is also significant. However, factors such as temperature, precipitation, shoreline length and extent of peat, important for some other marsh birds, were not statistically relevant.

The areas with the highest lane densities also had the highest number of three species considered at risk in Finland, the common aquatic warbler, Eurasian bittern and marsh harrier. The northern limit of breeding appears to be determined by the transition from a 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 rails.

Occasionally, more unusual locations are used. A pair in Scotland nested outdoors beside a road, and when an English nature reserve installed nest boxes for bearded tits (reed reeds with a wooden floor), rails nested both in the boxes and under the wooden floor, in the latter case sometimes with the tits in residence above.

Although primarily a lowland species, the rail breeds at 1,240 m in the Alps and at 2,000 m in Armenia. An Italian study suggested that reedbed birds need a minimum wetland area for breeding, which for the water rail is about 1 ha (2.5 acres), although the highest densities are found in marshes of 10 ha (25 acres) or more. (See Article: Phoenicurus Phoenicurus)

During migration and in winter, a wider range of wet habitats may be used, including flooded thickets or ferns.The freezing condition may force birds into more open places such as ditches, garbage dumps and gardens, or even onto exposed ice. A Welsh study suggested that individual winter territories overlap, with each bird using a significant proportion of the reedbed. After site desertion in freezing weather, the birds return to their previous home range.

A density of 14 birds per hectare (6.6 per acre) was recorded. Birds wintering in Iceland depend on warm geothermal currents and can access them through tunnels under the snow. When not feeding, they may shelter in holes and crevices in solidified lava. This species sometimes wanders outside its normal range and vagrants have been found in the Azores, Madeira, Mauritania, the Arctic, Greenland, Malaysia and Vietnam.

Behavior

This rail is a hidden species, its striped plumage making it difficult to see in its wetland habitat. Its laterally compressed body allows it to glide through the densest vegetation, and it will “freeze” if caught out in the open. It walks with a high gait, although it adopts a squat posture when running for cover. It swims, when necessary, with the jerky movement typical of rails, and flies short distances over reeds with its long legs dangling.

Although their flight appears 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 charge each other with their necks outstretched when breeding, sometimes both members of a pair attack together. Large, heavily marked males are dominant in winter, when direct aggression is replaced by sharming while standing erect on tiptoe, head shaking and beak thrusting.

Breeding

The raccoon is monogamous and highly territorial when breeding. Birds mate after reaching their nesting areas, or possibly even before spring migration. In large wetlands with good conditions, birds may nest at a distance of 20-50 m (22-55 yards). Territories vary in size, but 300 m2 (360 square yards) is typical.

The pair courts and makes contact calls throughout the breeding season. The male selects the nest site which he displays to the female while posing with feathers raised from the back, wings arched over his back, tail extended and bill pointing vertically downward. This display is accompanied by a loud call. Before mating, she raises her wings and tail, and bows with her bill touching her breast. The male feeds the female during courtship and, when incubating, may leave the nest to display it to the male, walking around it, calling softly, rubbing his beak against his and making short runs to and from it.

The nest is made from any available wetland vegetation and constructed mainly by the male, usually in a single day. It is raised 15 cm (5.9 in) or more above the marsh level, and is sometimes built on clumps of roots, tree stumps, or similar supports. It may build up higher if the marsh waters begin to rise. The nest is 13-16 cm (5.1-6.3 in) wide and about 7 cm (2.8 in) high. It is well hidden and is approached by narrow paths.

Typical clutch is 6-11 eggs in most of the range, but appears to be smaller (5-8) in Kashmir at about 1,500 m altitude.Laying dates vary by location, from late March in Western Europe and North Africa, to late May in Kashmir and June in Iceland. Clutch size may be smaller early or late in the breeding season. The breeding season may be extended by replacement and second clutches.

Eggs are blunt and oval, smooth and slightly shiny; color varies from whitish to pinkish, with reddish and brownish spots mainly at the wider end that sometimes merge into a single spot. The variation in egg size across the four subspecies is much smaller than the differences among individual eggs; thus, the average egg size of the nominate subspecies, 36 mm × 26 mm (1.4 in × 1.0 in), is typical for the species as a whole. Egg weight is about 13 g (0.46 oz), of which 7% is shell.

Both parents incubate the eggs, although the female assumes most of this task. Eggs are incubated for 19-22 days until hatching, with at least 87% success. Food is brought to the nest by the other adult and passed to the seated parent who feeds the chicks. The precocial and downy hatchlings leave the nest within two days of hatching, but continue to be fed by their parents, although the nestlings also find some of their own food after about five days.

They are independent of their parents after 20-30 days and can fly at the age of 7-9 weeks. If a nest appears to have been discovered, the female may carry chicks or eggs one by one to another location; eggs are carried in the beak, but small chicks may be hidden under the wing. Sitting birds may remain on the eggs even when approached, attack the intruder, or feign injury as a distraction. The water rail can breed after its first year, and usually raises two young.

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

Feeding

Scratchers are omnivorous, although they feed primarily on animals. These include leeches, worms, gastropods, small crustaceans, spiders and a wide range of terrestrial and aquatic insects and their larvae. Small vertebrates such as amphibians, fish, birds and mammals may be killed or consumed as carrion. Vertebrates are impaled with a blow to the beak that breaks the spinal cord of the prey.

Plant foods, which are eaten most in autumn and winter, include the buds, flowers, shoots and seeds of aquatic plants, berries and fruits. In South Asia, paddy rice (harvested rice grains) may sometimes be eaten. Young rails feed mainly on insects and spiders. Food obtained from the ground or mud is usually washed in water before being eaten.

After rain, rails may probe soft ground for earthworms. This species occasionally feeds outdoors, even when not forced to do so by cold weather; Edmund Meade-Waldo described seven rails feeding in an open meadow. Despite its hidden nature, the water rail seems to thrive in captivity when feeding on animal food such as raw meat or earthworms; one individual was taught to jump for worms suspended from a fishing rod. (See Article: Turdus Viscivorus)

The rails follow defined routes when feeding, frequently returning to good hunting areas. These rails are versatile and opportunistic foragers. They will jump to take insects from plants, climb to find berries, or dislodge apples from trees so they can eat them on the ground. They will kill birds by impaling or drowning them, particularly if the bird’s ability to escape is restricted.

They are also nest predators, particularly of small reed-nesting birds such as the common reed warbler Water rails may defend a winter feeding territory, even if this is smaller than when breeding, with individuals perhaps less than 10 m (11 yards) away; preferred sites may hold hundreds of birds.

Aggressive behavior outside the breeding season may extend to attacks on other marsh rails such as spotted and Baillon’s box. One bird killed a bird caught with him in a Helgoland trap. They are also nest predators, particularly of small reed-nesting birds such as the common reed warbler.

Scrakes may defend a winter feeding territory, although it is smaller than when breeding, with individuals perhaps less than 10 m (11 yards) apart; preferred sites may hold hundreds of birds. Aggressive behavior outside the breeding season may extend to attacks on other marsh rails such as spotted and Baillon’s crake.