A bibliometric analysis: what do we know about metals(loids) accumulation in wild birds?

Metals and metalloids pollution is an important worldwide problem due to the social and ecological effects and therefore has been the subject of many disciplines and the adverse impacts have been documented. In this study, content analysis and trends of studies focused on heavy metal accumulation in birds were presented. For this purpose, a bibliometric network analysis of the studies that use the concepts of "pollution," "heavy metal," and "birds" together in the abstract, keywords, and titles of the papers was carried out. The purpose of choosing this research method was summarizing the relation between birds and environmental pollution in an understandable manner to determine metals(loids) pollution, which become an important environmental problem. Bibliometric data consisting of approximately 971 papers were evaluated with VOSviewer program using the network analysis method to answer the research questions. The results revealed that birds act as bioindicators in the determination of environmental pollution and that the contaminant metals deposited in the various tissues of birds provide preliminary information about environmental pollution. The most of bird studies emphasized that the metal accumulation was mostly in the liver, kidneys, and feathers and the accumulation caused serious problems in most of the vital activities of the birds. The USA is in the leading country in birds-heavy metal studies followed by Spain, Canada, and China. In addition, the mercury (Hg) was the most extensively studied heavy metal in these studies.

Until It's a regulation It's not my fight: Complexities of a voluntary nonlead hunting ammunition program

Wildlife and human health are at risk of lead exposure from spent hunting ammunition. Lead exposure persists for bald eagles due to bullet fragments in game animal gut piles and unretrieved carcasses, and is also a human health risk when wild game is procured using lead ammunition. Programs encouraging the voluntary use of nonlead ammunition have become a popular approach mitigating these effects. This study explored attitudes and experiences of United States Fish and Wildlife Service (USFWS) staff implementing an outreach program encouraging deer hunters to voluntary use nonlead ammunition on 54 National Wildlife Refuges (NWRs) in the Upper Midwest, U.S. to understand factors affecting program implementation. We conducted 29 semi-structured interviews of USFWS staff along with 60 responses from an open-ended survey question. Twelve themes emerged from the data and were grouped into three broad categories: (1) challenges of dealing with complex issues, (2) importance of messengers and messages, and (3) resistance from staff. Challenges of dealing with complex issues included administrative restraint and uncertainty, scope and scale of program, human health not an agency responsibility, contextual political influences, and public-private collaborations. Importance of messengers and messages included the importance of experience, and salience of human health risk. Finally, resistance from staff included skepticism of the science and motives behind the program, competing priorities for refuge staff, differing perceptions of regulatory and voluntary approaches, cost and availability of nonlead ammunition, and disregard by some about lead ammunition and human health risks. Staff identified numerous challenges implementing the program, many of which were external factors beyond the control of the participants. Understanding the factors affecting program implementation may help guide future efforts encouraging the voluntary use of nonlead ammunition.

Lead Contamination in Ground Venison from Shotgun-Harvested White-Tailed Deer (Odocoileus virginianus) in Illinois

Ground venison packets from shotgun- and archery-harvested White-tailed Deer in Illinois in 2013 and 2014 were analyzed for metal contamination. Radiographs indicated that 48% of 27 ground venison packets from 10 shotgun-harvested deer contained metal fragments, while none of the 15 packets from three archery-harvested deer contained fragments. ICP-MS analysis verified that all metal fragments from seven of the venison samples from shotgun-harvested deer were composed of lead, with average concentrations from 1.04 to 8.42 μg g^-1, dry weight. A single serving of ground venison containing one of these metal fragments embedded in it would be predicted to have a lead concentration ranging from 6.4 to 51.8 μg g^-1. Sixty percent of 20 commercial meat processing plants surveyed by phone in 2018 and 2019 indicated that they mixed venison from multiple deer when preparing ground venison products. However, our results do not show any cross-contamination in archery-harvested ground venison processed prior to the firearm hunting seasons.

Postmortem Evaluation of Reintroduced Migratory Whooping Cranes (Grus americana) in Eastern North America

We reviewed necropsy records of 124 Whooping Cranes (Grus americana) recovered following reintroduction of 268 individuals from 2001 to 2016 in the eastern US. Causes of death were determined in 62% (77/124) of cases facilitated by active monitoring that limited decomposition and scavenging artifact. The greatest proportions of mortality were caused by predation (0.468; 95% confidence interval 0.356-0.580; 36/77), collision with power lines or vehicles (0.260; 0.162-0.358; 20/77), and gunshot (0.169; 0.085-0.253; 13/77). Six deaths were attributed to infection (0.078; 0.018-0.138; 6/77), including bacterial and fungal etiologies. Lead analysis of 50 liver samples yielded two results with elevated concentrations (3.65 and 10.97 ppm wet weight), and 10 bone samples from partial carcasses lacking suitable liver tissue resulted in one elevated result (48.82 ppm dry weight). These data indicate that underlying subclinical or clinical lead toxicosis may be a factor in up to 5% of deaths attributed to predation or impact trauma. Brain cholinesterase activity testing indicated no exposure to organophosphate or carbamate pesticides (mean±SD=17.32±2.90 µmol/min/g, 31/71). The causes of death and potential underlying factors summarized in this study constitute the first definitive mortality survey of migratory Whooping Cranes based on a high carcass recovery rate. Causes of death by infectious etiologies remained comparatively rare in this study, and occurred as single cases with no evidence of sustained transmission among reintroduced Whooping Cranes.

Effects of lead from ammunition on birds and other wildlife: A review and update

Poisoning of wild birds following ingestion of lead from ammunition has long been recognised and considerable recent research has focused on terrestrial birds, including raptors and scavengers. This paper builds upon previous reviews and finds that both the number of taxa affected and geographical spread of cases has increased. Some lead may also be absorbed from embedded ammunition fragments in injured birds which risk sub-lethal and welfare effects. Some papers suggest inter-specific differences in sensitivity to lead, although it is difficult to disentangle these from other factors that influence effect severity. Sub-lethal effects have been found at lower blood lead concentrations than previously reported, suggesting that previous effect-level 'thresholds' should be abandoned or revised. Lead poisoning is estimated to kill a million wildfowl a year in Europe and cause sub-lethal poisoning in another ≥ 3 million. Modelling and correlative studies have supported the potential for population-level effects of lead poisoning in wildfowl, terrestrial birds, raptors and scavengers.