@techreport{
 title = {Assessment of mercury in Maine’s interior bald eagle population},
 type = {techreport},
 year = {2009},
 keywords = {Hg,Maine,Mercury,bald eagle},
 pages = {42 pp.},
 issue = {March},
 city = {Peer-reviewed report submitted to the U.S. Fish and Wildlife Service, Orono, Maine. 42 pp.},
 institution = {Biodiversity Research Institute},
 id = {87fe17a1-3fa3-3758-a653-9ce65cb1ea00},
 created = {2014-03-05T23:16:39.000Z},
 file_attached = {true},
 profile_id = {ab0f59ed-74df-3903-921d-6cd544d31123},
 group_id = {3addd0f7-d578-34d3-be80-24022cc062a1},
 last_modified = {2020-06-05T20:46:18.478Z},
 read = {true},
 starred = {false},
 authored = {false},
 confirmed = {true},
 hidden = {false},
 folder_uuids = {b52ff113-1df4-415c-85d5-2f2737ac48ec,1ae19bab-0f9b-49e3-8902-01e5cc468c8a},
 private_publication = {false},
 abstract = {Mercury pollution is prevalent in the northeastern U.S. due to a combination of high rates of atmospheric deposition from Midwest sources and an abundance of habitats in the Northeast that effectively produce methylmercury from mercury inputs. Ongoing research has documented elevated mercury levels in a variety of aquatic and terrestrial fish and wildlife in Maine. High mercury burdens have been linked to negative effects on behavior, physiology, and fledging success in birds. In this study, mercury exposure and the potential for reproductive impacts in freshwater-feeding bald eagles (Haliaeetus leucocephalus) in Maine were investigated. Between 2001 and 2006 (primarily 2004-2006), eaglet blood and shed adult feathers were collected from freshwater-based bald eagle nest territories throughout Maine. Tissues were analyzed for mercury to obtain insights on short-term and chronic exposure in eaglet and adult age classes, respectively. Nonviable and abandoned eggs were also collected and analyzed for mercury. Mercury patterns between habitats and among watersheds, relationships between mercury exposure and eagle productivity were evaluated. Temporal mercury trends were determined by comparing results in the present study to data collected in a previous U.S. Fish and Wildlife sponsored study (Welch 1994). Over the course of the study, blood was collected from 304 eaglets from 150 inland nest territories. All eaglets were marked with rivet-style numbered leg bands from the Bird Banding Laboratory and with rivet-style red, 2-digit, horizontally-coded auxiliary leg bands. Eaglet blood mercury concentrations ranged from 0.08 – 1.62 parts-per-million, ppm (mean 0.53 ppm wet weight, n = 150). Eaglets reared in lake habitats (mean 0.56 ppm, n = 115 territories) had higher mercury concentrations than those reared in river habitats (mean 0.44 ppm, n = 35 territories). Blood mercury levels in lake-based Maine eaglets were higher than concentrations reported in other regions of North America, and similar to populations with known point-source pollution origins (e.g., mercury mines, dredging). Shed adults feathers were collected from 103 nest territories. Mercury exposure in adult bald eagle feathers ranged from 7.5 - 93.0 ppm dry weight (mean 38.3 ppm). Mercury concentrations in shed adult feathers were higher at nest territories in lake habitats (mean 40.6 ppm, n = 79) than river habitats (mean 30.5 ppm, n = 24). Mean feather mercury concentrations in both habitats, particularly lakes, were higher in comparison to many North American populations studied by other researchers. Similar to patterns observed in eaglet blood, mercury concentrations for Maine lake-dwelling adult eagles were higher than or comparable to other sites in North America associated with acute mercury pollution problems. Twenty two nonviable and abandoned bald eagle eggs were collected. Mercury in eggs from 16 inland nest territories in Maine (mean 0.40 ppm fresh wet weight, range 0.09 - 0.90 ppm) was elevated compared to other eagle populations in the United States. The majority of eagle eggs collected in this study, however, contained mercury concentrations that were below levels currently associated with reduced hatching success in piscivorous wildlife. Statistically significant negative relationships were found between eaglet blood mercury concentrations and 3-, 5-, and 10-year eagle productivity (chicks fledged/occupied nest), but the - 3 - correlation was not strong. The negative correlation between mercury and productivity was most pronounced at lakes, where mercury concentrations were highest. This relationship may suggest a portion of Maine’s eagle population may be experiencing some reproductive impacts due to mercury exposure despite continuous population growth. No relationships were detected between adult feather mercury concentrations or egg mercury concentrations and eagle productivity. Relationships between eaglet blood mercury concentrations and productivity in this study may be confounded by exposure to organic contaminants such as PCBs. Mean eaglet blood mercury levels varied among 10 watersheds, with the St. Croix River watershed containing the highest levels, and inland Midcoast Maine containing the lowest levels. Limited sample sizes within habitat types and watersheds precluded rigorous statistical comparisons. Within the majority of watersheds, eaglet blood mercury concentrations were higher at lakes compared to rivers. However, several watersheds did not fit this pattern and require further explanation. Eaglet mercury exposure data were often consistent with findings in other biota (i.e., common loons, fish) used in other studies to delineate several areas of significant mercury concern (i.e., biological mercury hotspots) in the state. Eaglet blood mercury concentrations at inland nest territories sampled in 1991-1992 and again in the present study (2004 – 2006) were compared to evaluate potential temporal changes in mercury concentrations available to eagle nestlings. Statistical analyses suggest a possible effect of time period on bald eagle blood mercury concentrations, but significant differences were not detected between the two sampling periods within lake and river habitat types. Comparisons suggested that an increase in mercury uptake in birds reared in river habitats over the time interval. Small sample sizes limit the ability to draw robust conclusions between the two datasets. Recommendations for further research and management needs include identifying and linking point source databases in the state with bald eagle territories exhibiting elevated mercury levels, periodic monitoring of bald eagles at 10 to 15 year intervals, and additional sampling in watershed basins where there is limited mercury exposure data.},
 bibtype = {techreport},
 author = {DeSorbo, Christopher R. and Todd, Charles S. and Mierzykowski, Steven E. and Evers, David C. and Hanson, William}
}

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Ongoing research has documented elevated mercury levels in a variety of aquatic and terrestrial fish and wildlife in Maine. High mercury burdens have been linked to negative effects on behavior, physiology, and fledging success in birds. In this study, mercury exposure and the potential for reproductive impacts in freshwater-feeding bald eagles (Haliaeetus leucocephalus) in Maine were investigated. Between 2001 and 2006 (primarily 2004-2006), eaglet blood and shed adult feathers were collected from freshwater-based bald eagle nest territories throughout Maine. Tissues were analyzed for mercury to obtain insights on short-term and chronic exposure in eaglet and adult age classes, respectively. Nonviable and abandoned eggs were also collected and analyzed for mercury. Mercury patterns between habitats and among watersheds, relationships between mercury exposure and eagle productivity were evaluated. Temporal mercury trends were determined by comparing results in the present study to data collected in a previous U.S. Fish and Wildlife sponsored study (Welch 1994). Over the course of the study, blood was collected from 304 eaglets from 150 inland nest territories. All eaglets were marked with rivet-style numbered leg bands from the Bird Banding Laboratory and with rivet-style red, 2-digit, horizontally-coded auxiliary leg bands. Eaglet blood mercury concentrations ranged from 0.08 – 1.62 parts-per-million, ppm (mean 0.53 ppm wet weight, n = 150). Eaglets reared in lake habitats (mean 0.56 ppm, n = 115 territories) had higher mercury concentrations than those reared in river habitats (mean 0.44 ppm, n = 35 territories). Blood mercury levels in lake-based Maine eaglets were higher than concentrations reported in other regions of North America, and similar to populations with known point-source pollution origins (e.g., mercury mines, dredging). Shed adults feathers were collected from 103 nest territories. Mercury exposure in adult bald eagle feathers ranged from 7.5 - 93.0 ppm dry weight (mean 38.3 ppm). Mercury concentrations in shed adult feathers were higher at nest territories in lake habitats (mean 40.6 ppm, n = 79) than river habitats (mean 30.5 ppm, n = 24). Mean feather mercury concentrations in both habitats, particularly lakes, were higher in comparison to many North American populations studied by other researchers. Similar to patterns observed in eaglet blood, mercury concentrations for Maine lake-dwelling adult eagles were higher than or comparable to other sites in North America associated with acute mercury pollution problems. Twenty two nonviable and abandoned bald eagle eggs were collected. Mercury in eggs from 16 inland nest territories in Maine (mean 0.40 ppm fresh wet weight, range 0.09 - 0.90 ppm) was elevated compared to other eagle populations in the United States. The majority of eagle eggs collected in this study, however, contained mercury concentrations that were below levels currently associated with reduced hatching success in piscivorous wildlife. Statistically significant negative relationships were found between eaglet blood mercury concentrations and 3-, 5-, and 10-year eagle productivity (chicks fledged/occupied nest), but the - 3 - correlation was not strong. The negative correlation between mercury and productivity was most pronounced at lakes, where mercury concentrations were highest. This relationship may suggest a portion of Maine’s eagle population may be experiencing some reproductive impacts due to mercury exposure despite continuous population growth. No relationships were detected between adult feather mercury concentrations or egg mercury concentrations and eagle productivity. Relationships between eaglet blood mercury concentrations and productivity in this study may be confounded by exposure to organic contaminants such as PCBs. Mean eaglet blood mercury levels varied among 10 watersheds, with the St. Croix River watershed containing the highest levels, and inland Midcoast Maine containing the lowest levels. Limited sample sizes within habitat types and watersheds precluded rigorous statistical comparisons. Within the majority of watersheds, eaglet blood mercury concentrations were higher at lakes compared to rivers. However, several watersheds did not fit this pattern and require further explanation. Eaglet mercury exposure data were often consistent with findings in other biota (i.e., common loons, fish) used in other studies to delineate several areas of significant mercury concern (i.e., biological mercury hotspots) in the state. Eaglet blood mercury concentrations at inland nest territories sampled in 1991-1992 and again in the present study (2004 – 2006) were compared to evaluate potential temporal changes in mercury concentrations available to eagle nestlings. Statistical analyses suggest a possible effect of time period on bald eagle blood mercury concentrations, but significant differences were not detected between the two sampling periods within lake and river habitat types. Comparisons suggested that an increase in mercury uptake in birds reared in river habitats over the time interval. Small sample sizes limit the ability to draw robust conclusions between the two datasets. Recommendations for further research and management needs include identifying and linking point source databases in the state with bald eagle territories exhibiting elevated mercury levels, periodic monitoring of bald eagles at 10 to 15 year intervals, and additional sampling in watershed basins where there is limited mercury exposure data.","bibtype":"techreport","author":"DeSorbo, Christopher R. and Todd, Charles S. and Mierzykowski, Steven E. and Evers, David C. and Hanson, William","bibtex":"@techreport{\n title = {Assessment of mercury in Maine’s interior bald eagle population},\n type = {techreport},\n year = {2009},\n keywords = {Hg,Maine,Mercury,bald eagle},\n pages = {42 pp.},\n issue = {March},\n city = {Peer-reviewed report submitted to the U.S. Fish and Wildlife Service, Orono, Maine. 42 pp.},\n institution = {Biodiversity Research Institute},\n id = {87fe17a1-3fa3-3758-a653-9ce65cb1ea00},\n created = {2014-03-05T23:16:39.000Z},\n file_attached = {true},\n profile_id = {ab0f59ed-74df-3903-921d-6cd544d31123},\n group_id = {3addd0f7-d578-34d3-be80-24022cc062a1},\n last_modified = {2020-06-05T20:46:18.478Z},\n read = {true},\n starred = {false},\n authored = {false},\n confirmed = {true},\n hidden = {false},\n folder_uuids = {b52ff113-1df4-415c-85d5-2f2737ac48ec,1ae19bab-0f9b-49e3-8902-01e5cc468c8a},\n private_publication = {false},\n abstract = {Mercury pollution is prevalent in the northeastern U.S. due to a combination of high rates of atmospheric deposition from Midwest sources and an abundance of habitats in the Northeast that effectively produce methylmercury from mercury inputs. Ongoing research has documented elevated mercury levels in a variety of aquatic and terrestrial fish and wildlife in Maine. High mercury burdens have been linked to negative effects on behavior, physiology, and fledging success in birds. In this study, mercury exposure and the potential for reproductive impacts in freshwater-feeding bald eagles (Haliaeetus leucocephalus) in Maine were investigated. Between 2001 and 2006 (primarily 2004-2006), eaglet blood and shed adult feathers were collected from freshwater-based bald eagle nest territories throughout Maine. Tissues were analyzed for mercury to obtain insights on short-term and chronic exposure in eaglet and adult age classes, respectively. Nonviable and abandoned eggs were also collected and analyzed for mercury. Mercury patterns between habitats and among watersheds, relationships between mercury exposure and eagle productivity were evaluated. Temporal mercury trends were determined by comparing results in the present study to data collected in a previous U.S. Fish and Wildlife sponsored study (Welch 1994). Over the course of the study, blood was collected from 304 eaglets from 150 inland nest territories. All eaglets were marked with rivet-style numbered leg bands from the Bird Banding Laboratory and with rivet-style red, 2-digit, horizontally-coded auxiliary leg bands. Eaglet blood mercury concentrations ranged from 0.08 – 1.62 parts-per-million, ppm (mean 0.53 ppm wet weight, n = 150). Eaglets reared in lake habitats (mean 0.56 ppm, n = 115 territories) had higher mercury concentrations than those reared in river habitats (mean 0.44 ppm, n = 35 territories). Blood mercury levels in lake-based Maine eaglets were higher than concentrations reported in other regions of North America, and similar to populations with known point-source pollution origins (e.g., mercury mines, dredging). Shed adults feathers were collected from 103 nest territories. Mercury exposure in adult bald eagle feathers ranged from 7.5 - 93.0 ppm dry weight (mean 38.3 ppm). Mercury concentrations in shed adult feathers were higher at nest territories in lake habitats (mean 40.6 ppm, n = 79) than river habitats (mean 30.5 ppm, n = 24). Mean feather mercury concentrations in both habitats, particularly lakes, were higher in comparison to many North American populations studied by other researchers. Similar to patterns observed in eaglet blood, mercury concentrations for Maine lake-dwelling adult eagles were higher than or comparable to other sites in North America associated with acute mercury pollution problems. Twenty two nonviable and abandoned bald eagle eggs were collected. Mercury in eggs from 16 inland nest territories in Maine (mean 0.40 ppm fresh wet weight, range 0.09 - 0.90 ppm) was elevated compared to other eagle populations in the United States. The majority of eagle eggs collected in this study, however, contained mercury concentrations that were below levels currently associated with reduced hatching success in piscivorous wildlife. Statistically significant negative relationships were found between eaglet blood mercury concentrations and 3-, 5-, and 10-year eagle productivity (chicks fledged/occupied nest), but the - 3 - correlation was not strong. The negative correlation between mercury and productivity was most pronounced at lakes, where mercury concentrations were highest. This relationship may suggest a portion of Maine’s eagle population may be experiencing some reproductive impacts due to mercury exposure despite continuous population growth. No relationships were detected between adult feather mercury concentrations or egg mercury concentrations and eagle productivity. Relationships between eaglet blood mercury concentrations and productivity in this study may be confounded by exposure to organic contaminants such as PCBs. Mean eaglet blood mercury levels varied among 10 watersheds, with the St. Croix River watershed containing the highest levels, and inland Midcoast Maine containing the lowest levels. Limited sample sizes within habitat types and watersheds precluded rigorous statistical comparisons. Within the majority of watersheds, eaglet blood mercury concentrations were higher at lakes compared to rivers. However, several watersheds did not fit this pattern and require further explanation. Eaglet mercury exposure data were often consistent with findings in other biota (i.e., common loons, fish) used in other studies to delineate several areas of significant mercury concern (i.e., biological mercury hotspots) in the state. Eaglet blood mercury concentrations at inland nest territories sampled in 1991-1992 and again in the present study (2004 – 2006) were compared to evaluate potential temporal changes in mercury concentrations available to eagle nestlings. Statistical analyses suggest a possible effect of time period on bald eagle blood mercury concentrations, but significant differences were not detected between the two sampling periods within lake and river habitat types. Comparisons suggested that an increase in mercury uptake in birds reared in river habitats over the time interval. Small sample sizes limit the ability to draw robust conclusions between the two datasets. 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