The rufous-throated dipper Cinclus schulzi on rivers in north-west Argentina and southern Bolivia

Abstract

Surveys of river birds were made in north-west Argentina in October 1993 and in southern Bolivia in December 1994. Data were collected on foraging behaviour, breeding biology and breeding abundances of the Rufous-throated Dipper Cinclus schitlzi (a threatened species) on three river systems in Tucumán and Jujuy provinces in Argentina and on two river systems in Tarija department in Bolivia. Rufous-throated Dippers foraged from wetted rocks and when standing in water in riffles and on the edges of cascades and waterfalls; swimming or diving was not observed. Five nests were found in Argentina, two of which were incomplete. One had a clutch of two eggs and another contained two well-grown, feathered nestlings; the fifth was inaccessible. These records indicate that breeding starts early in the Argentinian spring. Nests of adjacent pairs of Rufous-throated Dippers were from c.650-1,200 m apart. Juvenile plumage resembles that of the adult. Some information is provided on the biometrics of seven birds caught in mist-nets, and on vocalizations and on the relative abundance of dippers, Torrent Ducks Merganetta armata and two species of Cinclodes. Possible threats to rivers within the range of the Rufous-throated Dipper include reservoir construction, hydroelectric and irrigation schemes, eutrophication, deforestation and stock-grazing. Pollution, reduced flows and river channel modification are more prevalent at lower altitudes below the breeding range of the Rufous-throated Dipper.