Avian nesting and roosting on glaciers at high elevation, Cordillera Vilcanota, Peru

Other than penguins, only one bird species the White-winged Diuca Finch (Idiopsar speculifera)-is known to nest directly on ice. liere we provide new details on this unique behavior, as well as the first description of a White fronted Ground-Tyrant (Muscisaxicola albifrons) nest, from the Quelccaya Ice Cap, in the Cordillera Vilcanota of Peru. Since 2005, >50 old White-winged Diuca Finch nests have been Ibund. The first 2 active nests were found in April 2014; 9 were found in April 2016, 1 of which was filmed for 10 d during the 2016 nestling period. Video of the nest revealed infrequent feedings (>1 h between visits), slow nestling development (estimated 20-30 d), and feeding via regurgitation. The first and only active White-fronted Ground-Tyrant nest was found in October 2014, beneath the glacier in the same area. Three other unoccupied White-fronted Ground-Tyrant nests and an eggshell have been found since, all on glacier ice. At Quelccaya, we also observed multiple species roosting in crevasses or voids (caves) beneath the glacier, at elevations between 5,200 m and 5,500 in, including both White-winged Diuca Finch and White-fronted Ground-Tyrant, as well as Plumbeous Sierra Finch (Phiygilus unicolor), Rufous-bellied Seedsnipe (Attagis gayi), and Gray-breasted Seedsnipe (Thinocorus orbignyianus). These nesting and roosting behaviors are all likely adaptations to the harsh environment, as the glacier provides a naicroclimate protected from precipitation, wind, daily mean temperatures below freezing, arid strong solar irradiance (including UV-B and UV-A). Indeed, the global range of White-winged Diuca Finch coincides relatively closely with the distribution of Andean glaciers. and because no nests are known to have been found away from ice, this species may be a glacier obligate. Given the number of individuals observed and diversity of species associated with, and possibly dependent on. the ice, ongoing loss of tropical glaciers may have a direct, negative effect on High Andean biodiversity.