Nesting biology of Hauxwell's Thrush (Turdus hauxwelli): with notes on altitudinal variation

Abstract

The genus Turdus has a nearly complete anthology of nesting descriptions for its 70 species. One species yet to have nesting described is Turdus hauxwelli, a Neotropical bird native to South America. In addition to an altitudinal range expansion, here we document 19 active T. hauxwelli nests from 2 elevational regions (400 and 1,350 m) in the Andes of Southeastern Peru. Along with detailed descriptions of nest measurements and composition, we also describe nesting behavior. We present detailed information on T. hauxwelli temperature fluctuations in nest and eggs, and nest attentiveness during incubation and nestling period. The average egg weight was 6.12 g with dimensions of 26.71 × 20.05 mm. The female conducted an average of 28 trips per day during incubation, which lasted 13.7 d while the nestling period lasted 14.25 d. The overall daily survival probability for the nests is 19.5%. Other nesting traits were also similar between sites, with only nest mass differing by 37% between elevations, and even greater at higher elevations. Nesting traits among Turdus species do not vary drastically, however, despite occupying a variety of ecosystems from sea level up to 4,500 m, suggesting a low evolutionary lability in nesting traits in this genus.