About Synallaxis brachyura Lafresnaye, 1843
The slaty spinetail (Synallaxis brachyura) measures 14 to 16 cm (5.5 to 6.3 in) in length and weighs 16 to 21 g (0.56 to 0.74 oz). Male and female individuals have identical plumage. For adults of the nominate subspecies S. b. brachyura, the face is mostly darker gray, with an added grayish supercilium. The crown and nape are deep rufous-chestnut. The back ranges from dark sooty brown to slate-brown, while the rump and uppertail coverts are slightly browner than the back. The wing coverts and the base of the flight feathers are deep rufous-chestnut, and the remaining sections of the flight feathers are dark brown. The tail is the same brown color as the rump and uppertail coverts; it is long, and the feather tips lack barbs, which creates a spiny appearance. The throat is blackish, the breast and sides are dark sooty brown, the belly is a paler, grayer brown, and the flanks and undertail coverts are browner than the belly. The iris ranges from reddish brown to orange-brown, the maxilla is black to gray, the mandible is gray to blue-gray, and the legs and feet can be olive-gray, gray, or blue-gray. Juveniles have a gray crown and nape; compared to adults, they have paler upperparts, duller wing coverts, and more olivaceous underparts. The subspecies differ in coloration from the nominate: S. b. nigrifumosa has a darker brown back, darker rufous crown and wings, and darker gray underparts. S. b. griseonucha is darker than the nominate subspecies, but paler than S. b. nigrifumosa. S. b. caucae has a paler crown, a grayer back, and paler grayish olive rump and uppertail coverts than the nominate.
Each subspecies of the slaty spinetail has a separate distribution: S. b. nigrifumosa occurs on the Caribbean slope from Honduras through Nicaragua and Costa Rica into Panama. S. b. griseonucha occurs on the Pacific slope from central Costa Rica south through western Panama, Colombia, and Ecuador into the Department of Tumbes in extreme northwestern Peru. S. b. brachyura occurs in northern Colombia, from Antioquia Department east to the Magdalena River valley. S. b. caucae occurs in the Cauca River valley in central Colombia. The slaty spinetail lives in a variety of landscapes, most of which feature dense undergrowth. These habitats include second-growth scrublands, riparian thickets, overgrown clearings, and the edges of montane evergreen and tropical evergreen forest. It is also found locally in thorn scrub, the edges of swamps, and gardens. Most of its range places it at elevations below 1,400 m (4,600 ft); in Costa Rica it occurs only below 1,200 m (3,900 ft), and in Colombia it can be found as high as 2,000 m (6,600 ft).
