A Growing Conspiracy: Recolonization of Common Ravens (Corvus corax) in Central and Southern Appalachia, USA

Abstract

Corvus corax (Common Raven, hereafter Raven) was historically ubiquitous throughout much of North America, but persecution and habitat loss after European settlement resulted in range reduction and population decline across much of the eastern US. Increasing numbers of confirmed sightings of Ravens in the eastern US over the past 70 years suggest rapid regional recolonization, particularly in central and southern Appalachia where, in many states, Ravens were thought to be extirpated or at least highly range-restricted. We compiled 64,611 Raven observations from multiple public and private sources across Appalachia between 1950 and 2016 and performed spatial analyses to characterize regional recolonization trends. The Appalachian Mountain range has served as both a refugium for Ravens during the late 19th and early 20th centuries and a regional source population for range expansion between 1950 and 2016. Ravens are now common in the mountainous areas of Appalachia and have recently expanded their range into lower elevations, including the successful recolonization of 4 states: Alabama, Kentucky, Ohio, and Tennessee. Spatial analyses demonstrated a 40% increase in the Raven's apparent geographic range in central and southern Appalachia, which now spans at least 470,380 km2. We present an updated map detailing current Raven distributions in central and southern Appalachia and review potential habitat, interspecific, and trophic factors aiding range expansion for Ravens.