Avifaunal responses after two decades of Polylepis forest restoration in central Argentina

The high Andean Polylepis woodlands are home to a unique biota, including an outstanding avifauna. They are one of the most threatened mountain ecosystems worldwide; accordingly, they have been the object of the first restoration initiatives in South America. Here, we evaluated the effectiveness of 20-year Polylepis australis woodland restoration efforts to recover the woodland bird communities. We recorded bird diversity and abundance in an ongoing restoration site (with a high proportion of woodland) and in a control site, where no active restoration efforts were made (with a high proportion of grasslands and bare soil), 15 and 20 years after the start of the restoration project. We compared the avifauna of these sites with that of reference mature woodlands, using published records of the study region. At the ongoing restoration site, bird diversity increased over time, as well as abundances of species associated with P. australis, whereas those parameters remained stable at the control site. Our results are the first evidence that active restoration of P. australis entails passive restoration of the avifauna occurring in these unique upland forests