Trilling tapaculo

The trilling tapaculo was previously considered a subspecies of unicolored tapaculo (Scytalopus unicolor) but was elevated to species status based on differences in their vocalizations. Though it is monophyletic, there are song variations in different parts of its range that suggest that there might be undefined subspecies.[3][4][5]

The trilling tapaculo is 10.5 cm (4.1 in) long. Males weigh 17.5 to 21 g (0.62 to 0.74 oz) and females 15.4 to 18 g (0.54 to 0.63 oz). Adult males are usually dark gray above and lighter gray below, though sometimes dark gray all over. The flanks and crissum (the area around the cloaca) are dark reddish brown with dusky bars. The female is similar to the male but paler with a dark brown wash. The juvenile is similar to the female with the addition of a scaly appearance due to yellowish edges to feathers.[5]

The trilling tapaculo is found on the east slope of the Andes from southern Amazonas, Peru, southeastward to western Santa Cruz in Bolivia. It inhabits the undergrowth of humid montane forest between the elevations of 1,800 and 2,500 m (5,900 and 8,200 ft) in Peru. In Bolivia it is found from 2,000 to 3,200 m (6,600 to 10,500 ft) and locally to 3,300 m (10,800 ft).[5]

The IUCN has assessed the trilling tapaculo as being of Least Concern. It has a large range, and though its population has not been quantified it is believed to be fairly large and stable.[1]