Interactive Mortality Factors in Common Loons From Maritime Canada

Daoust, Pierre‐Yves; Conboy, Gary; McBurney, Scott; Burgess, Neil M.

doi:10.7589/0090-3558-34.3.524

Cited by 56 publications

(40 citation statements)

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“…Furthermore, mercury levels in the brains of three birds that we analyzed specifically to compare with elevated levels in the liver did not even approach the 15 mg/kg threshold for overt intoxication in non-piscivorus birds (Heinz, 1996). These three loons in our study with 371, 89, and 25.3 mg/kg mercury in liver respectively showed 4.5, 3.1, and 1.48 mg/kg in the brain, similar to the findings of Daoust et al (1998) for ten loons from New Brunswick, Canada. In these respects, common loons may be similar to seabirds in tolerating high mercury concentrations (Thompson, 1996).…”

supporting

confidence: 77%

“…As has been noted by Spitzer (1995), Forrester et al (1997), Ausperger et al (1998) and Daoust et al (1998), mortalities of common loons may frequently be the result of a interplay of factors and/or events, and determining primary causes is often difficult. More straight-forward, however, is recognition of the substantial mortality of common loons at inland locations in eastern Canada, the northeastern United States, and probably elsewhere from ingestion of lead sinkers and lure weights.…”

mentioning

confidence: 99%

“…An interaction of mortality factors has been proposed to account for die-offs that occasionally occur in common loons wintering along the Atlantic and Gulf coasts of North America (Spitzer, 1995;Forrester et al, 1997;Augsperger et al, 1998). Complex etiologies also were proposed for many of the thin loons in a mortality survey in Atlantic maritime Canada (Daoust et al, 1998). A better understanding of the mortality factors of this species will help identify present and future threats to this icon of the northern lakes and the ecosystems in which it lives.…”

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confidence: 99%

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Necropsy Findings and Environmental Contaminants in Common Loons from New York

Stone

Okoniewski

2001

Journal of Wildlife Diseases

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Diagnostic and analytical findings are presented for 105 common loons (Gavia immer) found dead or debilitated in New York (USA) from 1972-99. Aspergillosis (23% of cases) and ingestion of lead fishing weights (21%) were the most common pathologies encountered. Stranding on land, shooting, other trauma, gill nets, air sacculitis and peritonitis, and emaciation of uncertain etiology accounted for most of the remaining causes of disease or death. Analysis for total mercury in the liver of 83 loons yielded a geometric mean (gm) of 10.3 mg/kg (wet basis) and range of 0.07 to 371 mg/ kg, with emaciated birds generally showing higher levels. Organochlorine contaminant levels in brain were generally low, principally consisting of PCB's (gm ϭ 2.02 mg/kg) and DDE (0.47 mg/kg).

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confidence: 77%

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confidence: 99%

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confidence: 99%

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Necropsy Findings and Environmental Contaminants in Common Loons from New York

Stone

Okoniewski

2001

Journal of Wildlife Diseases

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“…Elevated levels of Hg were found in tissues of birds that died of chronic, often multiple diseases [36] or of starvation coupled with cold stress [37]. Common loons (Gavia immer) that died in poor body condition had higher levels of Hg and more intestinal trematodes than those that died in good body condition [38], and Hg levels have been positively correlated with the intensity of parasitic infestations in common eiders [7]. It was not possible to determine definitively whether Hg contributed to the deaths of animals in the studies listed above, in part because redistribution of Hg among tissues, with a resulting increase in liver concentrations, may have occurred as the animals lost weight before they died.…”

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confidence: 99%

Survival rates and blood metal concentrations in two species of free‐ranging North American sea ducks

Wayland

Drake

Alisauskas

et al. 2008

Enviro Toxic and Chemistry

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Abstract-Populations of several species of North American sea ducks have declined in the past few decades. Exposure to environmental contaminants, particularly metals, has been proposed as one of many possible factors contributing to these declines. Population dynamics are influenced by survival rates and breeding effort. In the present study, we examined the relationships between blood metal concentrations (Cd, Pb, Se, and Hg) and apparent annual survival and recapture probabilities (the latter as a surrogate for breeding effort) in adult females of two sea duck species, the king eider (Somateria spectabilis) and the white-winged scoter (Melanitta fusca), both of which have experienced declines in continental population during in recent years. No support was found for the hypothesis that exposure of white-winged scoters to these metals or of king eiders to Cd, Se, and Pb adversely affected probabilities of apparent annual survival. We detected a weak negative relationship ( ϭ Ϫ0.833) between Hg and annual survival ␤ of king eiders, but the 90% confidence interval of the slope estimate overlapped zero (Ϫ2.439 to ϩ0.672). Recapture probabilities were unrelated to concentrations of Cd, Se, and Pb in either species. Evidence indicated that Hg concentrations affected recapture probability in white-winged scoters ( ϭ Ϫ194.77; 90% confidence interval, Ϫ203.770 to Ϫ185.778). Mercury levels were low ␤ in both species, and blood samples may not adequately represent long-term exposure to Hg. Therefore, conclusions regarding Hg effects on these birds should be considered with caution.

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“…More recently, the detrimental effects of anthropogenically deposited lead have been documented in waterbirds and upland birds (Franson, 1996). In the common loon (Gavia immer), poisoning through ingestion of lead fishing weights occurs throughout its geographic range (Locke and Bagley, 1982;Daoust et al, 1998;Stone and Okoniewski, 2001), and on lakes in New England, lead poisoning is the leading cause of loon death (Pokras and Chafel, 1992). On the Yukon-Kuskokwim Delta (YKD) in western Alaska (USA), documented waterfowl mortality events have been attributed to ingestion of spent lead shot (Franson et al, 1995), and lead exposure could be influencing the population dynamics of breeding spectacled eiders (Somateria fischeri), long-tailed ducks (Clangula hyemalis), and common eiders (Somateria mollissima) in the region (Flint et al, 1997;Grand and Flint, 1998 comm.).…”

mentioning

confidence: 99%

Lead Shot Poisoning of a Pacific Loon in Alaska

Wilson

Oyen

Sileo

2004

Journal of Wildlife Diseases

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Lead poisoning, associated with ingestion of spent lead shot, was diagnosed in an adult female Pacific loon (Gavia pacifica) observed with partial paralysis on 13 June 2002 and found dead on 16 June 2002 on Kigigak Island, Yukon Delta National Wildlife Refuge, western Alaska, USA. A necropsy revealed three pellets of ingested lead shot in the loon's gizzard and a lead liver concentration of 31 ppm wet weight, which was consistent with metallic lead poisoning. This is the first report of lead poisoning in a Pacific loon and is the only account of lead toxicosis associated with ingestion of lead shot in any loon species breeding in Alaska.

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Interactive Mortality Factors in Common Loons From Maritime Canada

Cited by 56 publications

References 0 publications

Necropsy Findings and Environmental Contaminants in Common Loons from New York

Necropsy Findings and Environmental Contaminants in Common Loons from New York

Survival rates and blood metal concentrations in two species of free‐ranging North American sea ducks

Lead Shot Poisoning of a Pacific Loon in Alaska

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