Nests and Nest Site Characteristics of Rufous-Throated Dipper (Cinclus schulzi) in Mountain Rivers of Northwestern Argentina

Abstract

The Rufous-throated Dipper (Cinclus schulzi) is an endemic and threatened bird that inhabits the mountain rivers of southern Yungas of Argentina and Bolivia. This is the rarest and least known species of the genus, in part because of its restricted distribution. The aim of this study was to describe the nests and nest sites of the Rufous-throated Dipper in mountain rivers of northwestern Argentina. Five rivers were surveyed in transects of 3 to 6 km long from 2010 to 2013. The shape, size, substrate and building material of nests and nest and non-nest characteristics were assessed and compared in plots of 2 by 2 m. Plots with nests were compared to non-nesting plots for a number of habitat characteristics. Most nests found (78.57%; n = 28) had a globular shape, were attached to rocky substrates and were built using moss. The height of nests above the water level (P = 0.02), slope (P = 0.03) and watercourse width (P < 0.01) varied among rivers. Plots at nest sites had significantly higher values of some habitat characteristics than non-nesting plots, including emergent rocks (P < 0.01), slope (P < 0.02), greater number of rapids (P < 0.01), number of pools (P < 0.01), water velocity (P < 0.05), and river depth (P < 0.01), but had narrower watercourse width (P < 0.01). Previously, the understanding of the breeding ecology of the Rufous-throated Dipper was based only on anecdotal evidence. Understanding the breeding habitat requirements is a prerequisite for the development of a conservation action plan for this threatened species.