Aztec Rail Rallus tenuirostris Scientific name definitions

Aztec Rail, also known as Mexican Rail, occupies highland freshwater marshes in central Mexico. Until recently, this rail was classified as a subspecies of King Rail (R. elegans) of eastern North America, but phylogenetic analyses revealed that Aztec Rail is more closely related to Ridgway's Rail (R. obsoletus), of the lowlands of southwestern United States and northwestern Mexico, than it is to King Rail. The biology of Aztec Rail presumably is similar to that of King, Ridgway's, and other related species, but Aztec Rail has received little attention to date from field biologists

33–42 cm; male 271–331g, female 220–268g. Male dark morph is generally duller, somewhat less dark and less boldly marked on upperparts than R. elegans  , and has white chin and throat contrasting with broad pale cinnamon-pink malar stripe; underparts rufous, flanks barred dull brown (with pinkish wash) and white to pinkish-cinnamon, undertail-coverts mostly plain white; legs brownish-flesh. Pale morph has centre of underparts (breast centre to to upper belly) very pale, white with pinkish-cinnamon wash. Sexes similar. Juvenile is duller and darker above than adult, and paler, whitish with light pinkish-cinnamon wash, below, lower underparts palest, flanks mottled grey-brown and washed light pinkish.

C Mexico.

Highland freshwater marshes; uses seasonal wetlands, as well as permanent, freshwater ones. Occurs at up to at least 2500 m; recorded down to 800 m (2 Williams, S.O. (1989). Notes on the rail Rallus longirostris tenuirostris in the highlands of central Mexico. Wilson Bull.. 101: 117-120. Close ).

Resident, with some seasonal dispersal. Appearance in smaller seasonal areas of marsh probably due to dispersal from permanent wetlands in rainy season (May/Jun–Sept) (2 Williams, S.O. (1989). Notes on the rail Rallus longirostris tenuirostris in the highlands of central Mexico. Wilson Bull.. 101: 117-120. Close ).

Very like that of R. elegans. Breeding-season advertising call of both sexes a series of “chac” notes; loud, harsh series of “kik” or “kuk” in courtship. Also gives soft, rapid “tuk”.

Lays in May–Aug, possibly from Apr and extending to Sept. One nest was a domed structure made from spikerush (Eleocharis), placed in seasonal stand of spikerush 45–60 cm in height (2 Williams, S.O. (1989). Notes on the rail Rallus longirostris tenuirostris in the highlands of central Mexico. Wilson Bull.. 101: 117-120. Close ); this apparently typical, nest-site being in freshwater swamp or marsh or in seasonally swamped upland field. Clutch of five eggs, whitish with brown spots, in one nest found in mid Aug (2 Williams, S.O. (1989). Notes on the rail Rallus longirostris tenuirostris in the highlands of central Mexico. Wilson Bull.. 101: 117-120. Close ).

Not globally threatened. Currently considered Near Threatened. Has limited range, restricted to freshwater marshes in highlands of C Mexico. Global population not known; presumed to be fairly small, perhaps between 10,000 and 20,000 individuals. Was reported as being locally common in 1950s, e.g. in extensive marshes W of Mexico City, but even then grazing around edges of marshes was evident. Currently believed to be declining over much of range owing to habitat degradation and loss. Permanent wetlands in C Mexico are already in degraded condition, and total area of available habitat suitable for this species becomes very limited towards end of dry season (Oct–Apr/May); moreover, habitats reported as under additional threat from increasing agricultural, industrial and urban development (2 Williams, S.O. (1989). Notes on the rail Rallus longirostris tenuirostris in the highlands of central Mexico. Wilson Bull.. 101: 117-120. Close ). The scale and severity of threats need to be clarified. Recommended that wetlands within the species’ historical range be surveyed in order to obtain accurate data on population and trends. All wetland habitats within its range require effective protection.