Effect of Embedded Lead Shot on Body Condition of Common Eiders

During waterfowl hunting a large number of birds are shot but not instantly killed. Some will die within a few days as a direct consequence of heavy injuries, whereas another proportion is only lightly injured and will survive for an extended period of time although their survival may still be affected. We predicted that embedded body shot (when not instantly lethal) will cause reduced body condition among common eiders (Somateria mollissima), as we assumed such birds to be physical disadvantaged (e.g., as to mobility and foraging) from their injuries. Among birds collected during 3 winters (2000–2002) by Inuit hunters and fishermen in Nuuk, southwest Greenland, we X-rayed and dissected 762 common eiders to extract information about embedded lead shot and body condition. After adjusting for structural body size, year and date of sampling, habitat, and sampling method, we found that embedded lead shot had a significant effect on juvenile body condition. Wounded juvenile birds carried on average 19% less fat than unwounded juveniles. In accordance with a priori predictions, we did not detect an impact of wounding on the body condition of immature and adult birds. For most of these older birds, the shooting incidence took place .1 year before they were collected, and the insignificant test results indicated the absence of a long-term effect on body condition once birds survived the initial effect of wounding. For juvenile birds, the wounding effect most likely added to other causes of mortality; however, additional knowledge about natural mortality is required to estimate the net consequence on population dynamic. (JOURNAL OF WILDLIFE MANAGEMENT 70(6):1644–1649; 2006)