Water rail

Description

The adult of the nominate subspecies is a medium-sized rail,23–28 cm (9.1–11.0 in) long with a 38–45 cm (15–18 in) wingspan.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 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.