Removing lowermost dams can reestablish fish passage on Great Lakes tributaries. This can increase the transfer of contaminants from anadromous fish to piscivorous wildlife upstream; however, concentrations of bioaccumulative contaminants in Great Lakes fish have decreased over the last several decades. We analyzed concentrations of PCBs and the toxic equivalence (TEQs) calculated from PCBs, DDTs, other organochlorine pesticides, and PBDEs in the plasma of bald eagle nestlings above and below lowermost dams on five river systems in Michigan from 1999 to 2013. We examined relationships between contaminants and metrics of reproductive success from 1997 to 2018, including the effects of year and location relative to the lowermost dam. Σ20PCB and p,p’-DDE were important in characterizing differences in contaminant mixtures above and below dams. Concentrations of contaminants were generally greater below dams than above. There were generally greater nest success and more nestlings per nest below dams, but nest location explained little variability (R2 values = 0.03–0.15). Neither Σ20PCB nor p,p’-DDE was a significant predictor of 5-year productivity means by river reach despite concentrations exceeding previously established effects thresholds for healthy bald eagle populations in the Great Lakes (≥ 1 nestling/nest). Our study indicates that dams may continue to reduce the upstream movement of contaminants to bald eagles, but at the measured concentrations, contaminants did not impair productivity and reproductive success as indicated by nestlings per nest. Additional information about population dynamics could clarify population-level effects of contaminants on bald eagles and to what degree these populations are self-sustaining throughout the Great Lakes.

Anthropogenic inputs of heavy metals and metalloids pose a risk to wetlands due to their long retention time in sediment, high toxicity at low concentrations, and biological accumulation. This study aimed to assess risk from seven heavy metals (cadmium:Cd, chromium:Cr, copper:Cu, mercury:Hg, nickel:Ni, lead:Pb, zinc:Zn) and one metalloid (arsenic:As) along a trophic pathway by quantifying contaminant loads in muskrat livers, roots of invasive hybrid cattail (Typha x glauca), and in sediment at Horicon National Wildlife Refuge, a wetland of international importance in southeastern Wisconsin, United States. Overall, comparison to literature and thresholds from the Environmental Protection Agency led us to conclude that heavy metals and metalloids pose a low risk to refuge biota with maximum concentrations as follows in sediment, T. x glauca roots, and muskrat livers in mg/kg dry weight: Zn—82, 54, 111, Pb—42, 43, 0.06, Cu—26, 59, 13, Ni—22, 5, 0.7, Cr—20, 3, 0.5, As—6, 11, 0.08, Cd—3, 1, 0.08, Hg—0.1, 0.02, 0.08, a finding which was further supported by low bioconcentration factors between sample types. A spatial analysis using GIS revealed hotspots for Cd, Cr, Cu, Ni, and Zn in sediment in one subplot. However, even in hotspots concentrations mostly fell below protective thresholds and were similar to or lower than concentrations found in a prior survey from 1990 (α < 0.05). Overall, while anthropogenic influences are undoubtedly present, we interpret the concentrations found here to be relatively low and present them as points of comparison regarding risk to plants and mammals for others conducting similar surveys on wetlands.

Public communication is increasingly recognized as a key component in successful natural resource management within government agencies responsible for conservation. However, communication practices and beliefs among government conservation scientists and practitioners are not well studied or understood. Herein, we present the results of a communication survey disseminated to U.S. Fish and Wildlife Service employees working for the agency's Ecological Services program, a program charged with endangered species recovery. We asked respondents about public communication practices and beliefs, and factors that may motivate or discourage participation in public communication activities. Study respondents reported the lowest levels of participation in media-related, one-way communication activities, including writing educational materials and answering media inquiries. Respondents reported most frequently engaging in one-on-one communication with stakeholders. Although our results suggest that respondents engage in frequent communication with stakeholders, our results also suggest that they mostly communicate with stakeholders remotely, and especially by email, rather than in person. Furthermore, only 36% reported that they go out of their way to visit people in communities. On the other hand, a majority agreed that they learn new things about species and landscapes (80%) from conversations with stakeholders and often use this knowledge to solve conservation problems (89%). With respect to factors that encourage and discourage participation, 93% of respondents indicated that a desire to produce better conservation outcomes motivates them to communicate with stakeholders and the public. Many agreed that a lack of time was an obstacle to participating in public communication (68%), but an even larger majority (86%) indicated that public unfamiliarity with the U.S. Fish and Wildlife Service presented a barrier to public communication. Similarly, a majority of employees agreed that public and stakeholder unfamiliarity with themselves and their work also presented a communication barrier (62%). Our findings suggest that agencies responsible for conservation may want to assess whether the agency and its employees adequately invest in communication activities that foster public familiarity.

We investigated concentrations of blood total mercury (THg) in three extant populations of endangered Whooping Crane (Grus americana). Blood THg was greater in cranes reintroduced during 2001–2008 that range in the eastern US (median = 0.31 ug/g ww) than both wild cranes in central North America (median = 0.11 ug/g ww) and from captivity (median = 0.01 ug/g ww). The median THg blood concentrations in the two free-ranging populations of Whooping Cranes were low compared to reproductive toxic thresholds suggested for other large bird species (> 4.3 ug/g ww), but a singular elevated concentration was observed in one crane (1.04 ug/g ww; 6% of samples from the reintroduced population). These results likely reflect variable dietary Hg exposure among these populations, but should prompt additional biomonitoring to discern risk of greater Hg exposure nearer to the time of breeding and potential effects on productivity.

There are multiple sources of lead in the environment. However, scientific evidence points to spent lead ammunition as the most frequent cause of lead exposure and poisoning in scavenging birds in the United States. Despite the ban on its use for waterfowl hunting, lead ammunition is still widely used for other hunting and shooting activities. Therefore, it can remain on the landscape in carcasses not retrieved and in discarded offal piles. Carcasses and gut piles can be attractive food sources to scavenging birds that can ingest bullet fragments or shot while feeding. Scavenging birds may be particularly vulnerable to exposure and effects of lead due to their foraging strategies and food preferences, physiological processes that facilitate the absorption of lead, and demographic traits. Numerous lines of evidence support ammunition as the source of exposure in the majority of lead poisoned scavenging birds and include the recovery of ingested lead fragments or shot from exposed birds, observations of birds feeding on contaminated carcasses, isotopic signatures of lead in tissue that match that found in ammunition, patterns of mortality coincident with hunting seasons, and the lack of abundant evidence for other lead sources. Lead can be replaced in ammunition by alternative metals that are currently available and present limited environmental threats.

In 2012, we examined lead exposure in 58 bald eagles Haliaeetus leucocephalus found dead in Iowa, Minnesota, and Wisconsin. We determined lead concentrations in livers, examined differences in exposure among ages and between sexes, and recorded clinical signs consistent with lead poisoning. Most (60%) of the bald eagles had detectable lead concentrations, and 38% of the 58 had concentrations within the lethal range for lead poisoning. We found no differences in exposure based on sex or age, but we did find an inverse relationship between body and liver mass and liver lead concentration. The high percentage of lead-exposed bald eagles encouraged us to further examine potential sources of lead in our local environment. We initiated a study on the Fish and Wildlife Service's Upper Mississippi River National Wildlife and Fish Refuge to investigate if discarded offal piles from hunter-killed deer were a potential source of lead exposure to scavenging wildlife such as the bald eagle. Radiographs showed that 36% of offal piles in our sample area contained lead fragments ranging from 1 to 107 particles per pile. Our study indicated that 1) lead exposure rates for bald eagles found dead in our Upper Midwest study area were high, 2) more than one-third of the bald eagles found dead in Iowa, Minnesota, and Wisconsin had liver lead concentrations consistent with lead poisoning, and 3) discarded offal piles from deer shot with lead ammunition can be a potential source of lead exposure for bald eagles.

Mining and smelting in the Southeast Missouri Lead Mining District has caused widespread contamination of soils with lead (Pb) and other metals. Soils from three study sites sampled in the district contained from approximately 1,000–3,200 mg Pb/kg. Analyses of earthworms [33–4,600 mg Pb/kg dry weight (dw)] collected in the district showed likely high Pb exposure of songbirds preying on soil organisms. Mean tissue Pb concentrations in songbirds collected from the contaminated sites were greater ( p < 0.05) than those in songbirds from reference sites by factors of 8 in blood, 13 in liver, and 23 in kidney. Ranges of Pb concentrations in livers (mg Pb/kg dw) were as follows: northern cardinal ( Cardinalis cardinalis ) = 0.11–3.0 (reference) and 1.3–30 (contaminated) and American robin ( Turdus migratorius ) = 0.43–8.5 (reference) and 7.6–72 (contaminated). Of 34 adult and juvenile songbirds collected from contaminated sites, 11 (32 %) had hepatic Pb concentrations that were consistent with adverse physiological effects, 3 (9 %) with systemic toxic effects, and 4 (12 %) with life-threatening toxic effects. Acid-fast renal intranuclear inclusion bodies, which are indicative of Pb poisoning, were detected in kidneys of two robins that had the greatest renal Pb concentrations (952 and 1,030 mg/kg dw). Mean activity of the enzyme delta-aminolevulinic acid dehydratase (ALAD) in red blood cells, a well-established bioindicator of Pb poisoning in birds, was decreased by 58–82 % in songbirds from the mining sites. We conclude that habitats within the mining district with soil Pb concentrations of ≥1,000 mg Pb/kg are contaminated to the extent that they are exposing ground-feeding songbirds to toxic concentrations of Pb.

We estimated mercury exposure and bioaccumulation in sparrow feathers to determine variation among age groups, between sparrow species, and between feather types. Results of feather mercury studies in piscivorous birds indicate that mercury concentrations tend to increase with age and differ between feather types; however, data for insectivorous birds are lacking. We estimated mercury exposure of two insectivorous and sympatric tidal marsh sparrows: coastal plain swamp sparrow (Melospiza georgiana nigrescens), and seaside sparrow (Ammodramous maritimus). Tidal marshes have favorable conditions for mercury methlyation, thus it is likely that tidal marsh sparrows are exposed to methylmercury. We found no difference in mercury concentrations between males and female birds of both species. Adult swamp sparrow feather mercury concentrations did not differ among adult age groups; therefore, mercury was not found to increase with age in sparrows at the site. Hatch-year birds had significantly greater feather mercury concentrations compared with adult birds for both species. Mercury concentrations in adult seaside sparrows were twice as high as those in adult swamp sparrows suggesting species-specific variation, although concentrations in hatch-year sparrow species did not differ. Mercury concentrations differed between feather types in adults of both species. The first primary feather of both species had at least three times greater mercury concentrations than the outer tail feather possibly reflecting varying depuration rates with feather type.

The acute oral toxicity of the anticoagulant rodenticide diphacinone was found to be over 20 times greater in American kestrels (Falco sparverius; median lethal dose 96.8 mg/kg body weight) compared with Northern bobwhite (Colinus virginianus) and mallards (Anas platyrhynchos). Modest evidence of internal bleeding was observed at necropsy, although histological examination of heart, liver, kidney, lung, intestine, and skeletal muscle revealed hemorrhage over a wide range of doses (35.1-675 mg/kg). Residue analysis suggests that the half-life of diphacinone in the liver of kestrels that survived was relatively short, with the majority of the dose cleared within 7 d of exposure. Several precise and sensitive clotting assays (prothrombin time, Russell's viper venom time, thrombin clotting time) were adapted for use in this species, and oral administration of diphacinone at 50 mg/kg increased prothrombin time and Russell's viper venom time at 48 and 96 h postdose compared with controls. Prolongation of in vitro clotting time reflects impaired coagulation complex activity, and generally corresponded with the onset of overt signs of toxicity and lethality. in view of the toxicity and risk evaluation data derived from American kestrels, the involvement of diphacinone in some raptor mortality events, and the paucity of threshold effects data following short-term dietary exposure for birds of prey, additional feeding trials with captive raptors are warranted to characterize more fully the risk of secondary poisoning. Environ. Toxicol. Chem. 2011;30:1213-1222. (C) 2011 SETAC

The acute oral toxicity of the anticoagulant rodenticide diphacinone was found to be about 20 times greater to American kestrels (LD50=97 mg/kg) than to northern bobwhite (LD50=2,014 mg/kg). Several precise and sensitive clotting assays (prothrombin time, Russell's Viper venom time, thrombin clotting time) were adapted for use in these species, and this combination of assays is recommended to detect effects of diphacinone and other rodenticides on coagulation. Oral administration of diphacinone over a range of doses (sublethal to the extrapolated LD15) prolonged prothrombin time and Russell's Viper venom time within 24 to 48 hrs post-exposure. Prolongation of in vitro clotting time reflects impaired coagulation complex activity and was detected before or at the onset of overt signs of toxicity and lethality. These data will assist in the development of a pharmacodynamic model to assess and predict rodenticide toxicity to non-target avian species.

The anticoagulant rodenticide diphacinone was slightly toxic (acute oral LD50 2014 mg/kg) to Northern bobwhite (Colinus virginianus) in a 14-day acute toxicity trial. Precise and sensitive assays of blood clotting (prothrombin time, Russell's Viper venom time, and thrombin clotting time) were adapted for use in quail, and this combination of assays is recommended to measure the effects of anticoagulant rodenticides. A single oral sublethal dose of diphacinone (434 mg/kg body weight) prolonged clotting time at 48 h post-dose compared to controls. At 783 mg/kg (approximate LD02), clotting time was prolonged at both 24 and 48 h post-dose. Prolongation of in vitro clotting time reflects impaired coagulation complex activity, and was detected before overt signs of toxicity were apparent at the greatest dosages (2868 and 3666 mg/kg) in the acute toxicity trial. These clotting time assays and toxicity data will assist in the development of a pharmacodynamic model to predict toxicity, and also facilitate rodenticide hazard and risk assessments in avian species.

Mercury (Hg) contamination from industrial sources is pervasive throughout North America and is recognized by the US Environmental Protection Agency as a health hazard for wildlife and humans. Avian species are commonly used as bioindicators of Hg because they are sensitive to contaminants in the environment and are relatively easy to sample. However, it is important to select the appropriate avian species to use as a bioindicator, which should be directly related to the project objectives. In this study, we tested the utility of two tidal marsh sparrows, Seaside (Ammodramus maritimus) and Saltmarsh (Ammodramus caudacutus) sparrows, as bioindicator species of the extent of Hg contamination in tidal marshes along the Delaware Bay. To determine the possibility of using one or both of these species, we estimated sparrow blood Hg burden in five Delaware watersheds. We found no difference in Hg concentrations between species (F (1,133) < 0.01, P = 0.99), but Saltmarsh Sparrows had limited sample size from each site and were, therefore, not appropriate for a Delaware Bay-wide Hg indicator. Seaside Sparrows, however, were abundant and relatively easy to sample in the five watersheds. Seaside Sparrow blood Hg levels ranged from 0.15 to 2.12 ppm, differed among drainages, and were greatest in two drainages distant from the Delaware Bay shoreline (F (4,95) = 2.51, P = 0.05). Based on a power analysis for Seaside Sparrow blood Hg, we estimated that 16 samples would be necessary to detect differences among sites. Based on these data, we propose that Seaside Sparrows may be used as a tidal marsh Hg bioindicator species given their habitat specificity, relative abundance, widespread distribution in marsh habitats, ease of sampling, and limited variation in blood Hg estimates within a sampling area. In Delaware Bay, Saltmarsh Sparrows may be too rare (making them difficult to sample) to be a viable tidal marsh Hg bioindicator.