Widespread exposure to lead affects the body condition of free-living whooper swans Cygnus cygnus wintering in Britain

Exploring the recovery of a large wetland using black-necked swan blood parameters and body condition 16 years after a pollution-induced disturbance

Resilience theory has taken center stage in tackling the challenge of wetland recovery on a fast-changing planet. Because of waterbirds' enormous dependence on wetlands, their numbers have long been used as surrogates for wetland recovery over time. However, immigration of individuals can mask actual recoveries at a given wetland. One alternative to expanding the knowledge of wetland recovery is the use of physiological parameters from aquatic organism populations. We explored the variations in the physiological parameters of black-necked swan (BNS) before, during, and after a 16-year period of a pollution-induced disturbance that originated in a pulp-mill wastewater discharge. This disturbance triggered the precipitation of iron (Fe) in the water column of the Río Cruces Wetland in southern Chile, one of the main sites for the global population of BNS Cygnus melancoryphus. We compared our recent (2019) original data (body mass index [BMI], hematocrit, hemoglobin, mean corpuscular volume, blood enzymes, and metabolites) with available datasets from the site obtained before the pollution-induced disturbance (2003) and immediately after the disturbance (2004). Results indicate that, 16 years after the pollution-induced disturbance, some important parameters of animal physiology did not return to their pre-disturbance state. For instance, BMI, triglycerides, and glucose were significantly higher in 2019 than in 2004, right after the disturbance. By contrast, the hemoglobin concentration was significantly lower in 2019 than in 2003 and 2004, and uric acid was 42% higher in 2019 than in 2004. Our results demonstrate that, despite higher BNS numbers with larger body weights present in 2019, the Río Cruces wetland has only partially recovered. We suggest that the impact of megadrought and wetland disappearance far from the site results in high rate of swan immigration, casting uncertainty about using the number of swans alone as honest indicators of wetland recovery after a pollution disturbance. Integr Environ Assess Manag 2023;19:663-675. © 2023 SETAC.

Spatial, temporal and environmental differences in concentrations of lead in the blood of Mute swans from summer and winter sites in Poland

Lead (Pb) is a highly toxic pollutant and represents a serious threat to wildlife, affecting various systems in animal bodies. Especially prone to Pb poisoning are waterbirds, which may inadvertently ingest spent gunshot, fishing sinkers and contaminated sediments. This research thus focused on evaluating Pb concentrations in the blood of 170 Mute swans (Cygnus olor; a widespread species of waterbirds) at their summer (urban locations in Małopolskie and rural locations in Świętokrzyskie regions) and winter (the urban section of Wisła River in Krakow) sites in Poland (Europe). The study concentrated on comparing blood Pb concentrations according to sites and locations, verifying the influence of sex and age factors, examining the impact on hematocrit (Ht), glutathione (GSH) levels and body condition. Mean blood Pb concentrations (measured with ICP-OES) differed significantly between summer and winter sites (Regression by Maximum Likelihood Estimation (RML), p < 0.001) reaching higher values at winter sites. Concentrations did not differ from year to year (RML, p = 0.028). At summer sites, concentrations differed from location to location: swans from urban locations in Małopolskie had higher blood Pb concentrations (0.055 μg/g) than from rural Świętokrzyskie (0.008 μg/g; RML, p < 0.001). In summer and winter birds, neither sex nor age groups differed significantly the concentrations (RML, p > 0.231). Pb concentrations correlated weakly with Ht and GSH levels (Spearman test) and had no influence on body condition (proxied by scaled mass index; GLM, p = 0.246). We concluded that differences between summer and winter sites were dictated mainly by the type of habitat (rural vs. urban) that birds occupied in different seasons.

Metal(loid) pollution, not urbanisation nor parasites predicts low body condition in a wetland bioindicator snake

Urban ecosystems and remnant habitat 'islands' therein, provide important strongholds for many wildlife species including those of conservation significance. However, the persistence of these habitats can be undermined if their structure and function are too severely disrupted. Urban wetlands, specifically, are usually degraded by a monoculture of invasive vegetation, disrupted hydrology, and chronic-contamination from a suite of anthropogenic pollutants. Top predators-as bioindicators-can be used to assess and monitor the health of these ecosystems. We measured eight health parameters (e.g., parasites, wounds and scars, tail loss and body condition) in a wetland top predator, the western tiger snake, Notechis scutatus occidentalis. For three years, snakes were sampled across four wetlands along an urban gradient. For each site, we used GIS software to measure the area of different landscapes and calculate an urbanisation-landscape score. Previously published research on snake contamination informed our calculations of a metal-pollution index for each site. We used generalised linear mixed models to assess the relationship between all health parameters and site variables. We found the metal-pollution index to have the most significant association with poor body condition. Although parasitism, tail loss and wounds differed among sites, none of these parameters influenced body condition. Additionally, the suite of health parameters suggested differing health status among sites; however, our measure of contemporary landscape urbanisation was never a significant predictor variable. Our results suggest that the health of wetland predators surrounding a rapidly growing city may be offset by higher levels of environmental pollution.

Concentration and origin of lead (Pb) in liver and bone of Eurasian buzzards (Buteo buteo) in the United Kingdom

Ingestion of lead (Pb) derived from ammunition used in the hunting of game animals is recognised to be a significant potential source of Pb exposure of wild birds, including birds of prey. However, there are only limited data for birds of prey in Europe regarding tissue concentrations and origins of Pb. Eurasian buzzards (Buteo buteo) found dead in the United Kingdom during an 11-year period were collected and the concentrations of Pb in the liver and femur were measured. Concentrations in the liver consistent with acute exposure to Pb were found in 2.7% of birds and concentration in the femur consistent with exposure to lethal levels were found in 4.0% of individuals. Pb concentration in the femur showed no evidence of consistent variation among or within years, but was greater for old than for young birds. The Pb concentration in the liver showed no effect of the birds' age, but varied markedly among years and showed a consistent tendency to increase substantially within years throughout the UK hunting season for gamebirds. The resemblance of the stable isotope composition of Pb from buzzard livers to that of Pb from the types of shotgun ammunition most widely-used in the UK increased markedly with increasing Pb concentration in the liver. Stable isotope results were consistent with 57% of the mass of Pb in livers of all of the buzzards sampled being derived from shotgun pellets, with this proportion being 89% for the birds with concentrations indicating acute exposure to Pb. Hence, most of the Pb acquired by Eurasian buzzards which have liver concentrations likely to be associated with lethal and sublethal effects is probably obtained when they prey upon or scavenge gamebirds and mammals shot using Pb shotgun pellets.

Relationship between blood lead levels and physiological stress in mute swans (Cygnus olor) in municipal beaches of the southern Baltic

Lead is one of the non-essential metals that can become a serious environmental threat to the human population and wildlife causing various toxic impairments and pathologies. Waterfowl are especially sensitive to lead exposure as they stay in areas with a high risk of lead pollution due to hunting and fishing pressures. This study aims to determine recent blood lead levels in 45 live mute swans in the southern Baltic, in the Gulf of Gdańsk and to test the hypothesis that birds with elevated lead levels have a higher physiological stress. Mean concentration of lead in blood was 0.239 μg/g (range 0.028-0.675 μg/g). Almost half of the individuals examined in this study had increased blood Pb levels above the threshold level (0.23 μg/g), however none of them showed behavioural signs of Pb poisoning. Although the dominant food of mute swans staying at municipal beaches is bread delivered by people, which has low lead levels, lead was found in all blood samples taken from mute swans. In the study area, another possible source of lead poisoning, other than from ammunition, is connected with various anthropogenic activities, such as municipal sewage works. Moreover, poor diet results in greater susceptibility to absorption of lead and this may have an additional influence on elevated lead levels in blood of these birds. The Pb level was increased with heterophils to lymphocytes (H/L) ratio, which is used as a measure of longer-term physiological stress. The mean lead level in blood was higher in young birds than in adults, which may be a consequence of adults forcing them to take less calorific food from water plants containing elevated levels of lead in the area studied. However, it is difficult to disentangle this from other factors that may influence sensitivity to lead poisoning.

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.

The transition to non-lead sporting ammunition and fishing weights: Review of progress and barriers to implementation

This review presents evidence of lead exposure and toxicity to wildlife and humans from spent shotgun and rifle ammunition and fishing weights, and the barriers and bridges to completing the transition to non-lead products. Despite the international availability of effective non-lead substitutes, and that more jurisdictions are adopting suitable policies and regulations, a broader transition to non-lead alternatives is prevented because resolution remains divided among disparate human user constituencies. Progress has occurred only where evidence is most compelling or where a responsible public authority with statutory powers has managed to change mindsets in the wider public interest. Arguments opposing lead bans are shown to lack validity. Differing national regulations impede progress, requiring analysis to achieve better regulation. Evidence that lead bans have reduced wildlife exposure should be used more to promote sustainable hunting and fishing. Evidence of the lead contribution from hunted game to human exposure should shape policy and regulation to end lead ammunition use. The Special Issue presents evidence that a transition to non-lead products is both warranted and feasible.

Transitioning to non-toxic ammunition: Making change happen

If the multiple negative health impacts associated with lead ammunition are to be mitigated, a transition to the non-toxic alternatives is needed. This paper aims to map out the pathways to such a transition via a modification of Kotter's eight step theory of change, identifying key stakeholders, exploring options for those of us advocating change and the relationships between policy and persuasion. The focus is primarily on the UK, but it is of direct relevance to the rest of Europe and beyond. The theory of change model involves (1) creating urgency, (2) building coalitions, (3) creating a vision for change, (4) communicating that vision, (5) removing barriers to enable action, (6) creating short-term or geospatial wins, (7) building on the change and (8) embedding change in culture and regulation. The paper reflects on good progress to date in initial steps, but throughout subsequent steps creative engagement and other disciplines which appreciate the human dimensions such as mediation and psychology of behaviour change have been lacking. Although significant barriers remain for Step 5, the paper identifies the central vision of sustainability of hunting as a shared value around which most stakeholders can engage. The paper concludes that, given the growing momentum surrounding this issue in recent years, the phasing out of lead ammunition is at a tipping point.

Lead poisoning from ingestion of fishing gear: A review

Many publications have investigated the ingestion and toxicity of metallic lead from hunting and the shooting sports. However, there is limited literature on toxicity associated with the ingestion of lead fishing weights, despite our knowledge of damage caused to many species from entanglement in lines, nets, and fish-hooks. This paper surveys current knowledge of species poisoned by ingestion of lead fishing gear and the types of gear that have been implicated. We review the impacts of lead fishing tackle on wildlife species and human health and describe the efficacy of efforts to reduce the use of lead tackle through voluntary, educational, and regulatory approaches to encourage adoption of non-toxic fishing gear. The authors emphasize the need for further research and policy initiatives to deal with this serious problem.

Water body type and group size affect the flight initiation distance of European waterbirds

Human encroachment on nature grows constantly, increasing human-wildlife interactions. Flight initiation distance (FID, the distance at which animals flee from an approaching threat) is often used to measure antipredator behaviour and establish buffer zones to reduce human impact on wildlife. In this study, we approached 10 waterbird species on larger lakes and narrower rivers using a motorboat. We investigated whether water body type, season (winter/spring), approach starting distance, species body mass, and group size influenced bird FID. Average bird FID was 145 ± 92 m and differed between species. In general, FID of all species was larger on lakes than rivers and increased with increasing group size and approach starting distance. When analysed separately for the two most common species, common goldeneyes (Bucephala clangula) and mallards (Anas platyrhynchos), FID increased with increasing starting distance on rivers, but not lakes, likely because birds on lakes have enough time to evaluate the approaching object and take flight at great distance. Additionally, birds might perform different activities on lakes versus rivers, leading to varying energetic trade-offs between the two habitat types, which may affect the decision when to take flight. Finally, mallards aggregated in larger groups on lakes, which affected FID, likely due to enhanced visibility (i.e., earlier detection of the approaching boat) and detection probability (via increased group size) on lakes. Our results emphasize the importance of accounting for habitat characteristics, such as water body type, when studying waterbird FID, because they can affect the visibility of stimuli, group size and potentially animal behaviour, factors which should be taken into account when planning buffer zones for waterbirds in conservation areas.

Lead exposure biomarkers in the Common Loon

Lead in fishing tackle is a significant source of exposure to the environment, wildlife, and potentially humans. Common Loons (Gavia immer) are exposed to lead by eating fish which have lead tackle, or ingesting fishing weights or spent ammunition when they ingest small stones to aid in digestion. Blood lead is traditionally used as a biomarker of exposure in loons, but it only reflects recent exposures. Cumulative exposure measured via bone lead may better reflect the overall health of loons and their aquatic habitat. This study compared a portable x-ray fluorescence (XRF) device for measurement of bone lead with and without tissue overlying the bone on loon cadavers with measurements made by inductively coupled plasma mass spectrometry (ICP-MS) of different tissues from the loons. For this study we had 75 bone samples, 19 body fluid samples, and 17 liver lead samples. We found significant correlations between portable XRF bone lead measurements made with overlying tissue and ICP-MS measures of bone lead (R = 0.88), body fluid lead (R = 0.65), and liver lead (R = 0.71). Bone lead was found to be higher in loons collected from non-coastal regions. In assessing lead-related cause of death, bone lead proved more predictive than liver lead. Future studies should investigate the value of these biomarkers for both aquatic health and loon health to further validate our findings.

Hunting with lead ammunition is not sustainable: European perspectives

Much evidence demonstrates the adverse effects of lead ammunition on wildlife, their habitats and human health, and confirms that the use of such ammunition has no place within sustainable hunting. We identify the provisions that define sustainable hunting according to European law and international treaties, together with their guidance documents. We accept the substantial evidence for lead's actual and potential effects on wildlife, habitats and health as persuasive and assess how these effects relate to stated provisions for sustainability and hunting. We evaluate how continued use of lead ammunition negatively affects international efforts to halt loss of biodiversity, sustain wildlife populations and conserve their habitats. We highlight the indiscriminate and avoidable health and welfare impacts for large numbers of exposed wild animals as ethically unsustainable. In societal terms, continued use of lead ammunition undermines public perceptions of hunting. Given the existence of acceptable, non-toxic alternatives for lead ammunition, we conclude that hunting with lead ammunition cannot be justified under established principles of public/international policy and is not sustainable. Changing from lead ammunition to non-toxic alternatives will bring significant nature conservation and human health gains, and from the hunter's perspective will enhance societal acceptance of hunting. Change will create opportunities for improved constructive dialogue between hunting stakeholders and others engaged with enhancing biodiversity and nature conservation objectives.

Lead poisoning and other human-related factors cause significant mortality in white-tailed eagles

The white-tailed eagle (Haliaeetus albicilla) suffered a severe population decline due to environmental pollutants in the Baltic Sea area ca. 50 years ago but has since been recovering. The main threats for the white-tailed eagle in Finland are now often related to human activities. We examined the human impact on the white-tailed eagle by determining mortality factors of 123 carcasses collected during 2000-2014. Routine necropsy with chemical analyses for lead and mercury were done on all carcasses. We found human-related factors accounting for 60% of the causes of death. The most important of these was lead poisoning (31% of all cases) followed by human-related accidents (e.g. electric power lines and traffic) (24%). The temporal and regional patterns of occurrence of lead poisonings suggested spent lead ammunition as the source. Lead shot was found in the gizzards of some lead-poisoned birds. Scavenging behaviour exposes the white-tailed eagle to lead from spent ammunition.

Lead exposure in an urban, free-ranging parrot: Investigating prevalence, effect and source attribution using stable isotope analysis

Anthropogenic lead use has resulted in widespread environmental lead contamination known to affect wildlife populations worldwide. Ecotoxicological investigations in wild birds have thus far prioritised waterfowl and raptor species and primarily addressed contamination in natural ecosystems. Urban areas are increasingly associated with high levels of heavy metal contamination, however the risk of lead exposure in urban wildlife is less well known. This study investigates lead exposure in an urban population of North Island Kaka (Nestor meridionalis septentrionalis), an endemic New Zealand parrot. The inquisitive nature of these birds, an expanding urban population and increased availability of food in the urban environment are the primary factors implicated in their dispersal into urban areas where there is increased exposure to anthropogenic sources of lead. Blood lead concentrations were assessed in free-ranging birds to quantify the prevalence and magnitude of lead exposure. The impact of lead on physiological and neurological function was assessed using behavioural and clinical examinations. Finally, lead stable isotope analysis was employed to investigate lead in roofing material as a potential source of exposure in the urban environment. Results indicate a significant prevalence of lead exposure in this population (43.2%) with a maximum recorded plasma concentration of 50.7μg/dL. Although no mortality was observed during this study, lead exposure was associated with reduced body condition in kaka. Behavioural changes were present in one individual with the highest recorded blood lead concentration. Lead isotope values of roof-collected rainwater overlapped with kaka blood lead isotope values, suggesting this to be an important source of exposure in this population. The prevalence of lead exposure observed in this study suggests that lead is a toxin of importance to kaka in this urban area. Wildlife intoxications largely result from anthropogenic lead sources and this study identifies a previously undescribed urban source of lead for wildlife.

Environmental Lead and Wild Birds: A Review

Lead is a persistent inorganic environmental pollutant that affects humans and animals worldwide. Avian species are especially susceptible to lead exposure through consumption of lead ammunition, lead fishing tackle, and other contaminated food sources such as aquatic species ingesting lead contaminated sediments in mining areas. Even with government regulations on the use of lead ammunition in many countries, including the United States, terrestrial, aquatic, predatory, and scavenger avian species are still at risk of exposure to potentially lethal concentrations of lead. The toxicities seen in these avian species include increased oxidative stress and decreased anti-oxidant enzymes in hepatic and renal tissue. The avian immune system is also a target of lead and displays a number of altered functions suggestive of immune suppression; however, studies in wildlife and laboratory species remain too limited for definitive statements with regard to population risk. In contrast, lead clearly inhibits reproductive capabilities in adult birds, and alters growth and development of hatchlings. Environmental remediation for lead removal, which would lower toxic exposure in wildlife, presently is a monumental and prohibitively expensive effort. Wildlife exposure will therefore continue in contaminated areas, necessitating development of new remediation practices. These plans should aim toward limiting more widespread or heavier contamination of wildlife habitats. This chapter reviews presently available information of lead toxicity in wild bird species, and suggests continued monitoring and reduction strategies to reduce lead exposure for at-risk avian populations.

Trace element exposure of whooper swans (Cygnus cygnus) wintering in a marine lagoon (Swan Lake), northern China

Trace element poisoning remains a great threat to various waterfowl and waterbirds throughout the world. In this study, we determined the trace element exposure of herbivorous whooper swans (Cygnus cygnus) wintering in Swan Lake (Rongcheng), an important swan protection area in northern China. A total of 70 samples including abiotic factors (seawater, sediments), food sources (seagrass, macroalgae), feathers and feces of whooper swans were collected from the marine lagoon during the winters of 2014/2015 and 2015/2016. Concentrations of Cu, Zn, Pb, Cr, Cd, Hg and As were determined to investigate the trace element exposure of whooper swans wintering in the area. Results showed that there was an increasing trend in sediment trace element concentrations, compared with historical data. The trace element concentrations in swan feces most closely resembled those of Zostera marina leaves, especially for Cd and Cr. The Zn and Hg concentrations in the swan feces (49.57 and 0.01mg/kg, respectively) were lower than the minimum values reported in the literature for other waterfowls, waterbirds and terrestrial birds. However, the concentrations of the other five trace elements fell within the lower and mediate range of values reported for birds across the world. These results suggest that the whooper swans wintering in Swan Lake, Rongcheng are not suffering severe trace element exposure; however, with the increasing input of trace elements to the lagoon, severe adverse impacts may occur in the future, and we therefore suggest that the input of trace elements to this area should be curbed.

Sublethal Lead Exposure Alters Movement Behavior in Free-Ranging Golden Eagles

Lead poisoning of animals due to ingestion of fragments from lead-based ammunition in carcasses and offal of shot wildlife is acknowledged globally and raises great concerns about potential behavioral effects leading to increased mortality risks. Lead levels in blood were correlated with progress of the moose hunting season. Based on analyses of tracking data, we found that even sublethal lead concentrations in blood (25 ppb, wet weight), can likely negatively affect movement behavior (flight height and movement rate) of free-ranging scavenging Golden Eagles (Aquila chrysaetos). Lead levels in liver of recovered post-mortem analyzed eagles suggested that sublethal exposure increases the risk of mortality in eagles. Such adverse effects on animals are probably common worldwide and across species, where game hunting with lead-based ammunition is widespread. Our study highlights lead exposure as a considerably more serious threat to wildlife conservation than previously realized and suggests implementation of bans of lead ammunition for hunting.

Implications of mercury and lead concentrations on breeding physiology and phenology in an Arctic bird

Although physiological traits and phenology are thought to be evolved traits, they often show marked variation within populations, which may be related to extrinsic factors. For example, trace elements such as mercury (Hg) and lead (Pb) alter biochemical processes within wildlife that may affect migration and breeding. While there is a growing understanding of how contaminants may influence wildlife physiology, studies addressing these interactions in free-living species are still limited. We examined how four non-essential trace elements (cadmium, Hg, Pb and selenium) interacted with physiological and breeding measures known to influence breeding in a free-living population of common eider ducks (Somateria mollissima). We collected blood from female eiders as they arrived at a breeding colony in northern Canada. Blood was subsequently assessed for baseline corticosterone (CORT), immunoglobulin Y (IgY), and the four trace elements. We used model selection to identify which elements varied most with CORT, IgY, arrival condition, and arrival timing. We then used path analysis to assess how the top two elements from the model selection process (Hg and Pb) varied with metrics known to influence reproduction. We found that arrival date, blood Hg, CORT, and IgY showed significant inter-annual variation. While blood Pb concentrations were low, blood Pb levels significantly increased with later arrival date of the birds, and varied negatively with eider body condition, suggesting that even at low blood concentrations, Pb may be related to lower investment in reproduction in eiders. In contrast, blood Hg concentrations were positively correlated with eider body condition, indicating that fatter birds also had higher Hg burdens. Overall, our results suggest that although blood Hg and Pb concentrations were below no-effect levels, these low level concentrations of known toxic metals show significant relationships with breeding onset and condition in female eider ducks, factors that could influence reproductive success in this species.