Dogs, humans and island ecosystems: the distribution, antiquity and ecology of domestic dogs (Canis familiaris) on California's Channel Islands, USA

Abstract

Archaeologists have made significant contributions to our understanding of ancient island environments, including the timing and implications of the introduction of non-native animals (pigs, chickens, rats, etc.) by humans. Here, we focus on the historical ecology and biogeography of domestic dogs ( Canis familiaris) on California's Channel Islands during the Holocene. Dogs are the only animal known unequivocally to have been introduced by Native Americans to the islands, but relatively little is known about their distribution, antiquity or influence on native island fauna and flora. We identified a minimum of 96 dogs from 42 archaeological sites on six of the eight islands. Dogs were present for at least 6000 years and appear to have increased in abundance through time. Our analysis suggests that dogs, along with humans and island foxes ( Urocyon littoralis), would have had an impact on native animals and ecosystems, especially breeding birds and marine mammals. Dogs and island foxes likely competed with one another for food, however, and the impacts of dogs on island ecosystems may have been reduced by the presence of island foxes and the symbiotic relationship between dogs and humans. Dogs have been removed from all but one of the islands today, eliminating one of the few terrestrial carnivores present for most of the Holocene.