Contaminants were examined for trends over time, spatial variation based on disparate breeding areas, and relationships with measures of productivity. Most organochlorines and metals declined over time. Mercury was the only contaminant with possibly increasing concentrations in eggs. Egg and feather samples collected in 2000 will provide more information on mercury trends and effects. This study embodies 20 years of data on environmental contaminants in peregrine falcons nesting in Alaska.
Eggs were sampled for persistent organochlorines and metals. Nestling feathers were sampled for mercury and methyl mercury.
Unhatched, addled eggs were collected when nests were visited to count and band nestlings (no eggs were collected in 1981, 1985, and 1992). Fresh eggs were collected in 1984, 1989, 1995, and 2000 during occupancy surveys when adults were incubating. Whole eggs were wrapped in foil, cushioned for transport, and refrigerated as much as possible prior to removal of contents. Contents were removed by scoring the eggshell at the equator and placing contents in a chemically-clean jar (I-Chem or equivalent). Eggshell thickness (shell plus membranes) was reported as an average of three measurements taken on the equator of each egg with a micrometer graduated in units of 0.01 mm. Eggshell thickness measurements came only from shells of whole eggs, collected either as fresh or addled eggs; no measurements of eggshell fragments were included. If membranes were missing, 0.069 mm was added (Court et al. 1990). To assess percent of shell thinning, we compared thickness to a pre-1947 thickness of 0.360 ± 0.007 mm (95% C.L.) for 53 peregrine eggs from arctic and subarctic Alaska (Anderson and Hickey 1972). Feathers analyzed for mercury were the distal 1.5 cm of Secondary No. 4 from one side of the largest nestling, clipped using stainless steel scissors, and stored in a paper or plastic envelope. In eggs, organochlorines were measured from 1979-95 and metals were measured from 1988-95. Analytes measured and limits of detection (LODs) are summarized in Ambrose et al. (2000). Total PCBs were calculated as an Aroclor sum, and mercury was measured as elemental mercury. Eggs collected prior to 1988 were analyzed at Patuxent Wildlife Research Center. Eggs collected in 1988-95 were analyzed at Texas A & M, College Station, TX, USA, except for eggs collected in 1989 and 1991 which were analyzed at Mississippi State University, Mississippi State, MS, USA. Detailed analytical methods are available from the Patuxent Analytical Control Facility (PACF), Patuxent Wildlife Research Center, U.S. Fish and Wildlife Service, Laurel, MD, USA. Feathers were collected in 1989-91 and analyzed for total mercury at PACF or contract laboratories. Feathers were also collected in 2000 and analyzed for mercury and methyl mercury at Texas A & M, College Station, TX, USA .
Quality assurance and quality control (QA/QC) procedures followed U.S. Fish and Wildlife Service contractual standards. Acceptance criteria were spike recoveries of 80-120%, Standard Reference Material value within + 3 SD of the certified value, relative percent difference of duplicate samples within + 20%, and analysis of matrix blanks. Additionally, 10% of positive samples were confirmed by Gas Chromatography/Mass Spectrometry. Analytes that failed to meet QA/QC acceptance criteria were excluded from data summaries and analysis.