The Inaccessible Island rail (Laterallus rogersi) is a small secretive bird native to the isolated island in the south Atlantic. It is the smallest extant flightless bird in the world. The species was described by physician Percy Lowe in 1923 but had first come to the attention of scientists 50 years earlier.
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NocturnalNocturnality is an animal behavior characterized by being active during the night and sleeping during the day. The common adjective is "nocturnal",...
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CarnivoreA carnivore meaning 'meat eater' is an organism that derives its energy and nutrient requirements from a diet consisting mainly or exclusively of a...
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InsectivoresAn insectivore is a carnivorous plant or animal that eats insects. An alternative term is entomophage, which also refers to the human practice of e...
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TerrestrialTerrestrial animals are animals that live predominantly or entirely on land (e.g., cats, ants, snails), as compared with aquatic animals, which liv...
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CongregatoryCongregatory animals tend to gather in large numbers in specific areas as breeding colonies, for feeding, or for resting.
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OviparousOviparous animals are female animals that lay their eggs, with little or no other embryonic development within the mother. This is the reproductive...
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PrecocialPrecocial species are those in which the young are relatively mature and mobile from the moment of birth or hatching. Precocial species are normall...
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TerritorialA territory is a sociographical area that which an animal consistently defends against the conspecific competition (or, occasionally, against anima...
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Flightless birdFlightless birds are birds that through evolution lost the ability to fly. There are over 60 extant species including the well known ratites (ostri...
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Island endemicIsland endemic animals are found in a single defined geographic location, such as an island. Animals or organisms that are indigenous to a place ar...
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MonogamyMonogamy is a form of relationship in which both the male and the female has only one partner. This pair may cohabitate in an area or territory for...
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Not a migrantAnimals that do not make seasonal movements and stay in their native home ranges all year round are called not migrants or residents.
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starts withThe Inaccessible Island rail is dark chestnut-brown above and dark grey on the head and below, with degraded white barring on the flanks and belly, and adults have a red eye. The female is similar to the male but with paler grey and a faint brown wash on the underparts. It has a black bill, which is shorter than the head. The feathers of the Inaccessible Island rail are almost hair-like, and in particular, the flight feathers are degenerate, as the barbules on many of the feathers (but not all, as has sometimes been reported) fail to interlock, giving the feathers a ragged appearance. The wings are reduced and weak, and smaller than same-sized flying relatives, as is the sternum. The tail is short, 3.5 cm (1.4 in) in length, and the uppertail coverts and undertail coverts are nearly as long as the tail rectrices.
These birds are found only in the uninhabited Inaccessible Island in the Tristan da Cunha group in the mid-Atlantic Ocean. The island is 14 km2 (5.4 sq mi) in area and has a temperate wet oceanic climate with high rainfall, limited sunshine, and persistent westerly winds. These rails live in almost all habitats on the island and at all altitudes. They especially favor fields of tussock grass, and tussock grass mixed with ferns and sedges. This habitat is found close to the shore and surrounds most of the island on the steep cliffs. Inaccessible Island rails can also be found in upland fern-bush heath, dominated by wind-stunted tree-ferns and in the island forest in the central plateau. They also forage among boulders on the beaches and frequently use natural cavities among boulders or tunnels through grasses created by frequent use to move around while concealed.
Inaccessible Island rails live in family groups and are very territorial. The territories they defend are tiny. Due to the small size of their territories encounters between families and individuals are frequent, and confrontations and territorial calling are common. On meeting, confrontations start with loud trills or twittering, then birds may face off, standing very close to each other and displaying ritually with their heads lowered and their bills pointed towards the ground. They may circle, and continue displaying until one bird slowly retreats or a quick skirmish ensues and one bird is driven off. Inaccessible Island rails are diurnal but usually forage during the nighttime hours. They are highly vocal and pairs and families contact call frequently while feeding. A long trill is used when pairs meet and when confronting a rival. Rivals also make a long twitter 'keekeekeekeekee' which can be long and short and end in a 'keekeechitrrrr'. After skirmishes between rivals, the victorious bird may make a 'weechup weechup' call. Birds may make a monotonous 'tchik tchik tchok tchik' while hunting for prey, and the alarm call when predators are around is a short and hard 'chip'. They also make a variety of trilling calls while incubating, particularly when pairs swap places during incubation. Before changing places the incubating bird may make a 'chip chip chip', but they become silent when Tristan thrushes approach the nest.
Inaccessible Island rails are carnivores (insectivores). They mainly eat earthworms, amphipods, isopods, mites, and a range of insects such as beetles, flies, moths, caterpillars, and centipedes. Along with animal prey rails supplement their diet with berries as well as the seeds of some plants.
Inaccessible Island rails are monogamous and form long-lasting pair bonds. They are seasonal breeders, laying eggs between October and January. Rails construct their nests at the base of ferns with tussock grass, tussock grass clumps, or in tufts of sedges. The nests are domed and oval or pear-shaped, with the entrances near the narrow end of the nest and linked by a track or tunnel that can go up to half a meter away. The nests are typically built entirely of tussock grass or sedges. Where the construction material is tussock grass, larger leaves are used on the outside, and finer material lines the nest. The female lays 2 eggs; the eggs are greyish milk-white dotted with brown-rufous spots and lavender-mauve spots that are concentrated around the apex of the egg. Both parents incubate the eggs. They bring food to each other, which is either consumed on the nest or close to the nest. The eggs hatch within between 23-32 hours of each other and can be preceded by the chick in the egg calling for up to 45 hours before hatching. Newly hatched chicks are covered by downy black plumage and leave the nest within 24 hours. Both parents help raise and protect their young.
These birds have a tiny global range with a single population. Though still common within their tiny range, they are considered to be vulnerable if an invasive species were to reach Inaccessible Island. House mice, feral cats, and Brown rats, all of which would be a serious threat to this species, are not present on the island, nor have they ever been, but are present on nearby Tristan da Cunha, and could reach the islands via fishing vessels or other boats visiting the island (mice have been found on boats visiting the neighboring Nightingale Island). Fires of tussock grass, which were recorded in 1872 and 1909, are assumed to have killed large numbers of rails but have not occurred since.
According to the IUCN Red List, the total population size of the Inaccessible Island rail is 9,100-12,200 individuals or roughly 5,460-7,320 mature individuals. Currently, this species is classified as Vulnerable (VU) on the IUCN Red List, but its numbers today are stable.
Social animals are those animals that interact highly with other animals, usually of their own species (conspecifics), to the point of having a rec...