Common Ravens (Corvus Corax) Nesting on Alaska's North Slope Oil Fields

摘要

Resident populations of common ravens (Corvus corax) on the North Slope of Alaska appear to be increasing where anthropogenic resources are available. This includes numbers of ravens at the North Slope Borough's Prudhoe Bay Landfill during winter, and breeding pairs dispersed throughout the oil fields and other human settlements. The oil fields provide abundant anthropogenic resources in terms of food sources and infrastructure for nesting. In this study, we documented nest locations, nest and nest site characteristics, movements of adult and juvenile ravens, and diet of ravens breeding in the North Slope oil fields of Kuparuk and Prudhoe Bay. In addition, we collected data on marked ravens throughout Alaska from the public. We located a total of 89 nests in the oil fields from 2004-2007. From 2004-2006 we monitored nests to determine nest success and productivity and collected data on nest site characteristics. We captured and radio-tagged adult ravens, and marked both adult and juveniles with leg bands and patagial wing tags to estimate home ranges during breeding and document movements. VHF and satellite transmitters failed due to a variety of reasons, therefore data derived from these sources were limited. Ravens placed their nests on oil field infrastructure; 46% were located on processing facilities, 35% on drill sites, and the remaining on other structures including bridges, radar towers, and inactive drill rigs. More research is needed to assess projected population growth and impacts to specific local prey species. Management options for decreasing raven populations include eliminating access to landfills and other food sources, and removing nests.