First description of the nest and eggs of the Sooty-faced Finch

Abstract

Sooty-faced Finches (Lysurus crassirostris) occur in dense undergrowth of wet forests that border streams along the Caribbean slope of Costa Rica between 600 to 1500 m in altitude. Its distribution is from Cordillera de Tilaran in Costa Rica to eastern Panama (Slud, The birds of Costa Rica. Distribution and ecology. Bull. Amer. Mus. of Nat. Hist. 128, 1964; Stiles and Skutch, A guide to the birds of Costa Rica. Cornell Univ. Press, Ithaca, New York, 1989). On 5 May, 1993, 1 found a Sooty-faced Finch nest containing two eggs at the Reserva de San Ramdn on the Caribbean slope of Costa Rica (800 m; lO”13N ’ and 84”37W). ’ The nest was attached to a fern stem 1.5 m above the ground in primary forest. The nest was roofed and had a side entrance, the 15 X 13 cm cavity was lined with fern rootlets and bamboo leaves. A soft bulk of moss decorated with fern leaves and Selaginella surrounded the outer part of the cavity and extended, just touching the fern trunk, for 67 cm below the nest. The nest contained two short-oval shaped eggs (terminology of Harrison, Afield guide to nests, eggs and nestlings of North American birds. Collins, Toronto, Ontario, 1984) with the following dimensions and mass, respectively: 24.85 X 18.90 mm and 25.00 X 18.75 mm; and 4.5 and 4.6 g. The eggs were ivory-colored with vinaceous-pink spots (Smithe, Naturalists ’ color guide. Amer. Mus. Nat. Hist. New York, New York, 1975) covering most of the wide tip and dispersed speckles (of the same color) toward the narrow end. Embryonic development had just begun in one egg but not in the second. This is the first description of the nest and eggs of this species. The nest and eggs were deposited in the ornithology collection of the Museo National de Costa Rica.