Nesting of the Pampas Meadowlark (Sturnella defilippii) in Buenos Aires Province, Argentina

Abstract

Pampas grasslands are possibly the most severely degraded ecosystem in Argentina, mainly due to the advance of animal and crop farming. These activities have a negative impact on grassland birds, including the Pampas Meadowlark (Sturnella defilippii), a species considered Vulnerable. In this paper we present data from a reproductive group of Pampas Meadowlark in the vicinity of Bahía Blanca, Buenos Aires Province. During the spring and summer of 2003 we found 16 nests in a field with a low stocking rate. We recorded hatching and nest abandonment by nestlings, as well as predation and adult behaviour. We found the first nest on 18 November, and the others up until 6 December. Nests were arranged in a clustered pattern; they were cup shaped with an external diameter of 9.5 cm, an internal diameter of 8.9 cm and a depth of 5.2 cm. They were mainly constructed with grasses, and placed on the ground amongst tussocks of Stipa spp. and Piptochaetium spp. The mean clutch size was 3.14 eggs per nest. Half of the detected nests were predated. Our results reinforce the opinion of other authors concerning the importance of natural grasslands for the reproduction of this species.