Nesting is not the only activity for which Diuca speculifera utilize glaciers. On a nightly basis at Quelccaya, birds were observed flying toward the glacier margin, then cautiously alighting on nearby moraines and then on the ice itself. They arrived individually and in small groups. In a few cases they were observed entering cave-like areas within or beneath the glacier. On one pre-dawn occasion in 2008 Diuca-finches were observed in such a crevice (cf. crevasse), demonstrating that the glacier is used as a roosting place – or “nachtquartier” as termed by Niethammer in 1953 (Niethammer, G. 1953. Zur Vogelwelt Boliviens. Bonner Zoologische Beiträge 4:195-303). The original observation follows (p. 240), kindly translated from German by colleague Mathias Vuille.
"On the evening of 22 December 1951, an advance group of 6 Diuca preceded the larger main group of birds. This advance group arrived only near dusk (6:50 pm) in front of the glacier crevasse. I stood a little bit below on the ridge and wrote down the following: “despite the icy wind (-2° C), which made my hands nearly freeze to the binoculars, the birds do not fly directly into their shelter, but chase one another, visit the glacier crevasse, sit down at the edge of the crevasse, and then from time to time fly up with the wind. Only after one-quarter of an hour do they go into the crevasse, skillfully flying around icicles and disappearing inside (7 pm). It’s already getting dark (twilight). A Phrygilus unicolor also flies into the crevasse. Cold weather and increasing darkness lead me to start the descent. Then, however, I realize that the birds observed so far were only the advance group, because suddenly a much larger group of birds flies past me toward the crevasse, some alone, some in groups of two, very close to the ground and always on the north slope (with southerly wind!) Some rest on the way, in the rubble or on the bare glacier, and fly the distance to the night-lodging (nachtquarter) in stages. Thus, a large number of Diuca goes to the overnight accommodation, arriving later today than yesterday. The birds probably originate from a larger catchment area, because I estimate the group now gathered in the crevasse to be approximately 100 birds."
"The remarkable night lodging of Diuca was also well known to some skiers. They told me that the birds in earlier years spent the night in another glacier crevasse farther down on the glacier, until that crevasse was buried. The fact that Diuca often appear in pairs of two, and the active testicles of a male I hunted (they measured 6 x 4 mm), document that the birds still visited the group night-lodging, even once they reach breeding mood." BACK