• Common ravens in Alaska's North Slope oil fields: an integrated study using local knowledge and science

      Backensto, Stacia Ann (2010-05)
      Common ravens (Corvus corax) that nest on human structures in the Kuparuk and Prudhoe Bay oil fields on Alaska's North Slope are believed to present a predation risk to tundra-nesting birds in this area. In order to gain more information about the history of the resident raven population and their use of anthropogenic resources in the oil fields, I documented oil field worker knowledge of ravens in this area. In order to understand how anthropogenic subsidies in the oil fields affect the breeding population, I examined the influence of types of structures and food subsidies on raven nest site use and productivity in the oil fields. Oil field workers provided new and supplemental information about the breeding population. This work in conjunction with a scientific study of the breeding population suggests that structures in the oil fields were important to ravens throughout the year by providing nest sites and warm locations to roost during the winter. The breeding population was very successful and appears to be limited by suitable nest sites. The landfill is an important food source to ravens during winter, and pick-up trucks provide a supplemental source of food throughout the year. Further research will be necessary to identify how food (anthropogenic and natural) availability affects productivity and the degree to which ravens impact tundra-nesting birds.
    • Factors affecting survival of Arctic-breeding dunlin (Calidris alpina arcticola) adults and chicks

      Hill, Brooke Lynne; Hunter, Christine M.; Lindberg, Mark S.; Lanctot, Richard B. (2012-05)
      Accurate estimates of, and identifying factors affecting, survival and productivity can provide insight into population trends and help determine what management actions would most benefit a population. Only limited demographic data are available for many Arctic-breeding shorebird species. I estimated survival probabilities for Arctic-breeding Dunlin (Calidris alpina arcticola); for adults between 2003 and 2010, and for chicks in 2008 and 2009. Adult apparent survival probabilities were higher for males (0.60 ± 0.04) than females (0.41 ± 0.05), were higher for individuals initiating nests earlier in the season, and yearly variation was high. These apparent survival rates appear insufficient to maintain a stable population. Daily survival rates of chicks increased as insect biomass increased across all ages and hatch dates, but the relationship with age and hatch date depended on the values of the other variables. The probability of a chick surviving to 15 days of age showed a strong relationship with hatch date, peaking in early July then declining rapidly. Chick survival was much higher for young from first nests (0.71 0.07) than early (0.23 ± 0.19) or late (0.03 ± 0.61) replacement nests. This suggests replacement nests make a much smaller contribution to annual recruitment than first nests.