White-winged Diuca Finch (Diuca speculifera) Nesting on Quelccaya Ice Cap, Perú

—We found evidence of birds nesting directly on glacier ice of the Quelccaya Ice Cap in the Cordillera Vilcanota, Perú at elevations up to 5,300 m. Observations during June and July over several years consisted of numerous nests not in situ having obviously fallen from the steep and dynamic, retreating glacier margin. A typical nest was a bulky structure of grass and twigs with a dry mass of 160 g. The inner cup was nicely formed and lined with fine grass, measuring 6–7 cm in diameter and 4–5 cm deep. Feathers and entire wings of White-winged Diuca Finch (Diuca speculifera) were observed in association with the nests; this was the passerine species most commonly seen in the area. The evidence indicates the glacier nests were built and used by White-winged Diuca Finch, probably during the Austral autumn when onsite automated measurements indicate the wet season ends and air temperatures have not yet decreased. This is the first well-documented case of high-elevation avian nesting on glacier ice. Received 30 November 2006. Accepted 26 December 2007. Some birds are well adapted to environments which are seasonally dominated by snow or sea ice, but birds are not generally associated with 1 Climate System Research Center, Geosciences Department, University of Massachusetts, Amherst, MA 01003, USA. 2 Marion W. Cross School, Norwich, VT 05055, USA. 3 Corresponding author; e-mail: [email protected] glaciers. Only the Emperor Penguin (Aptenodytes forsteri) is known to routinely nest on ice, typically frozen sea-ice (i.e., fast-ice) but at times in association with ice shelves derived from glaciers (Kooyman 1993). Transient birds have been observed passing over mountain glaciers at high elevations outside the polar regions or discovered after succumbing to harsh environmental conditions (Krajick 2002; L. G. Thompson, pers. comm.). However, glacier surfaces are usually cold, actively changing through accumulation and ablation, and at times wet; conditions that are poorly suited for nesting and raising young birds. The ornithological literature contains only one detailed account of nesting on a glacier. This was the unusual circumstance where glaciers advancing into Alaska’s Prince William Sound overran a Black-legged Kittiwake (Rissa tridactyla) colony (Irons 1988). Previouslyused nest sites were unavailable and 77 kittiwake nests were constructed on the glacier face. All of these nests failed due to ablation and/or meltwater runoff which either dislodged the nests or caused them to disintegrate (Irons 1988; D. B. Irons, pers. comm.). The objective of this paper is to present evidence of nesting by White-winged Diuca Finch (Diuca speculifera) directly on glacier ice of the Quelccaya Ice Cap in Cuzco De614 THE WILSON JOURNAL OF ORNITHOLOGY • Vol. 120, No. 3, September 2008 FIG. 1. (A) White-winged Diuca Finch on Quelccaya Ice Cap at 5,200 m on 23 June 2007, (B) the same glacier in June 2005 with arrow indicating the approximate location of the first nest observation in 2005 and the nest described in text. Circled area of margin just above the proglacial lake is enlarged in (C) looking under the ice. The circle on (C) encloses a nest which is likely in situ, 3 m above rock surface with enlarged view in (D); note silt from meltwater runoff. partment, Perú (14 S, 71 W). Observations were made over several years during the Austral winter (Jun–Jul) in the course of conducting glacier and climate research on the ice cap. This is the first well-documented case of high-elevation avian nesting on a glacier, corroborating a second-hand report of ‘‘ice cave’’ nesting by White-winged Diuca Finch (Johnson 1967).