Aramides

Rails of the wood

Recent years have seen a number of shifts in the classification of rails, as authors have attempted to resolve conflicts between molecular and morphology-based studies of relationships, and clarified the status of divergent insular taxa. Nevertheless, one genus of rails that has so far remain stable in its conception is the Neotropical wood rails of Aramides.

Russet-naped wood rail Aramides albiventris, copyright Paul Cools.

Aramides includes eight or nine species of rail found in tropical and subtropical regions of South and Central America. Species have a relatively long bill and legs, and are generally dull in coloration with barred underwing coverts and a black tail (Marcondes & Silveira 2015). The base of the culmen is often expanded to form a rudimentary frontal shield (Olson 1973). Aramides species are inhabitants of forests and adjoining wetlands. Where their habits are known, they seem to be somewhat secretive birds, foraging at dusk or night. However, their loud, raucous calls may be heard at many times of day. Their diet is omnivorous, including small animals and plant matter. Nests are constructed in vegetation a metre or more above ground, and are typically tended by both parents.

Grey-cowled wood rail Aramides cajaneus, copyright Greg Lasley.

The various species of Aramides are all fairly similar in appearance, varying in size from about 28 cm long in the little wood rail A. mangle to 45 cm long in the giant wood rail A. ypecaha. Species often differ in their preferred habitat: the giant wood rail emerges into the open more frequently than its congeners, the red-winged wood rail A. calopterus inhabits the seasonally flooded forests of the upper Amazon, the rufous-necked wood rail A. axillaris is found along tropical coasts. Three species are found in Central America—A. axillaris, the russet-naped wood rail A. albiventris, and the grey-cowled wood rail A. cajaneus—with the remainder found in various parts of South America. Aramides cajaneus has the most expansive range in the genus, being found from Costa Rica south to northern Argentina and Uruguay. More restricted species include the brown wood rail A. wolfi, found in coastal regions of western Colombia and Ecuador. Aramides avicenniae has been recognised from a relatively small are of coastal mangroves in south-eastern Brazil, from São Paulo southwards (Marcondes & Silveira 2015) but may alternatively be treated as a subspecies of A. cajaneus. With the exception of A. wolfi (and possibly A. avicenniae), most Aramides species are not currently regarded as threatened.

Giant wood rail Aramides ypecaha, copyright Sebastián Lescano.

Olson (1973) expressed the opinion that Aramides and similarly unspecialised ‘wood rails’ from other parts of the world represented a sort of relictual primitive form for rails as a whole. More recent molecular studies have placed Aramides as part of a clade (recognised as the Pardirallini by Kirchman et al. 2021) including a variety of both long- and short-billed species but all from the Neotropical realm. The form may still be old-fashioned, but the affinities are squarely patriotic.

References

Kirchman, J. J., N. R. McInerney, T. C. Glarla, S. L. Olson, E. Slikas & R. C. Fleischer. 2021. Phylogeny based on ultra-conserved elements clarifies the evolution of rails and allies (Ralloidea) and is the basis for a revised classification. Ornithology 138: 1–21.

Marcondes, R. S., & L. F. Silveira. 2015. A taxonomic review of Aramides cajaneus (Aves, Gruiformes, Rallidae) with notes on morphological variation in other species of the genus. ZooKeys 500: 111–140.

Olson, S. L. 1973. A classification of the Rallidae. Wilson Bulletin 85 (4): 381–416.

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