The breeding of five species of Emberizidae and Fringillidae in the Reserve of Ñacuñán, Argentina

Abstract

The breeding of five species of Emberizidae and Fringillidae in the Reserve of Ñacuñán, located in the central Monte desert, is described. The laying period started in October or early November, and lasted until December or January. The average date of egg laying tended to be later in the wet 1997-1998 breeding season for Diuca diuca and, less clearly, for Saltatricula multicolor. All species built open-cup nests, although Diuca diuca used old nests of other birds (mainly Furnariidae) when nested in natural habitats; the open nests built by this species were found only beside the biological station of the reserve. Zonotrichia capensis placed the nests on the ground, usually covered by a tussock of grass. The remainder species used shrubs such as atamisque and zampa (Saltatricula multicolor), chañar trees (Diuca diuca using old nests of Asthenes baeri), natural or exotic planted trees and artificial structures from humans beside the biological station (Saltator aurantiirostris, Carduelis magellanica). Eggs were laid on consecutive days and clutch size was 3-4 eggs in all studied species. Three nests of Diuca diuca (43%) had eggs of the parasitic Molothrus bonariensis. In all cases, parasitized nests were placed around human settings. Mean clutch size of Saltatricula multicolor was larger in 1997-1998 compared to 1996-1997 and 1998-1999. Mean productivity in this bird species was 0.5 fledgings per active nest and 2.3 fledgings per successful nest. The duration of incubation and nestling periods, and chick characteristics after hatching are described.