Using audio playback to expand the geographic breeding range of an endangered species

Aim Species conservation typically involves working within the existing geographic range of that species. However, with habitat loss and climate change, conservationists may need to extend their work beyond the current range of a species. We attempted to extend the geographic breeding range of a rare species, Kirtland's warbler ( Setophaga kirtlandii ), by 225 km from the closest known breeding pairs and 550 km from its core population. Location Wisconsin, USA . Methods We broadcast conspecific song playbacks at two sites in landscapes that were far from source populations but had a history of intermittent occupancy. We also estimated the potential effect that additional use of this technique in Wisconsin could have on the global Kirtland's warbler population. Results The sites were initially unoccupied, but over the course of three years, playback attracted individuals to sites where they successfully reproduced. In the final year of the study, at least seven males and four females occupied the sites, producing 15 young. Based on the amount of appropriate habitat (5‐ to 15‐year‐old jack [ Pinus banksiana ] and red pine [ P. resinosa ]) in Wisconsin, we estimated that a population of approximately 250 pairs of Kirtland's warblers (10% of the global population) could eventually be supported. Main conclusion Although conspecific playback has often been reported to work over short distances, our success here demonstrates the potential for effectiveness over much greater distances, even in species with a small global population. This highlights that conspecific playback can be a powerful tool to assist recovery of endangered species, particularly in migratory species with a restricted distribution and high dispersal capabilities. As climate changes and humans alter the landscape, it may become crucial to attempt to establish populations beyond a species' current geographic range.