Behaviour, natural history, and annual cycle of the Henderson Island rail Porzana atra (Aves: Rallidae)

Abstract

The little known endemic Henderson Island rail (or Henderson rail) Porzflna atra, inhabits forest on the coastal plain and upraised plateau of Henderson Island. Rails were studied for 15 months from January 1991 to March 1992. The population was estimated at c. 6200 individuals living in pairs or cooperative groups of 3–4 adults on territories averaging about 1 ha. Two or three eggs were laid in covered or open nests near the ground from mid‐July to mid‐February. Up to five consecutive nesting attempts were made in cases where eggs or young chicks were lost. Adults laid a second clutch when chicks were fully feathered at about one month of age. Both sexes incubated and helped rear the young. Older chicks sometimes helped feed younger siblings. Dispersal of juveniles from the natal territory took place in April. Adult birds underwent a rapid, simultaneous post‐nuptial moult of the remiges in February‐April; the post‐juvenile moult involved body feathers only. Data on morphometries, breeding ecology, courtship behaviour and voice are compared with available information for the spotless crake P. tabuensis, the Henderson rail's closest relative and probable ancestor. These comparisons provide some information on how these two taxa have differentiated since rails arrived on Henderson Island some time in the last 380000 years.

The modern avifauna of the Pitcairn Islands

“…(Brooke, 1995) and the endemic landbirds of the Pitcairn group. Graves (1992) reported on the status of these landbirds and then more intensive work was carried out by Jones et al (1995) The Pitcairn Islands consist of four islands, the inhabited and ecologically disturbed island of Pitcairn itself and three uninhabited islands, the raised limestone atoll of Henderson and the low atolls of Oeno and Ducie. A more detailed account of the Islands in their geographical context is given by Spencer (1 995).…”

Rapid, independent evolution of flightlessness in four species of Pacific Island rails (Rallidae): an analysis based on mitochondrial sequence data

“…The species was extirpated on Laysan by the mid‐1920s, due to habitat destruction by introduced rabbits, but birds had been introduced to two islands in the Midway Atoll in the early part of the century and survived there until 1943, when rats were introduced, and the Laysan Rail was exterminated within two years (Olson 1999). P. atra still exists on Henderson Island in high densities (Jones et al 1995). Henderson is a 37 km 2 raised reef island in the Pitcairn group, with no permanent fresh water, and the island has been unoccupied by humans since at least 1600 (Brooke and Jones 1995).…”

Population status of four endemic land bird species after an unsuccessful rodent eradication on Henderson Island

“…To facilitate a comparison with historic reports we extrapolated the total population size of each species in 2015 by making explicit assumptions about the area over which point counts would sample individuals. Although this area was unknown, we used previous descriptions of territory size and likely flight distance of each species (Graves 1992, Brooke and Hartley 1995, Brooke and Jones 1995, Jones et al 1995), combined with personal observations in the field, to specify a minimum and maximum radius that seemed plausible for each species. These radii are a combination of both detection and movement distances.…”