Lead in ammunition: a persistent threat to health and conservation

Trace elements and heavy metals in black vultures (Coragyps atratus) and turkey vultures (Cathartes aura) in the southeastern United States

Many vulture species worldwide are declining at alarming rates due to a variety of anthropogenic causes, including exposure to pollutants and pharmaceuticals through consumption of contaminated carrion. However, little is known about the extent to which vultures are exposed to various contaminants as well as toxicity thresholds for trace elements and heavy metals. Our objective was to quantify levels of trace elements and heavy metals within black vulture (Coragyps atratus) and turkey vulture (Cathartes aura) tissues to determine the extent to which populations in the Southeastern United States are exposed to carrion that contains high levels of contaminants. We collected 34 black vulture liver samples and examined differences in trace element and heavy metal concentrations between sexes and age classes (adult and juvenile). Further, we collected 81 blood and 42 feather samples from additional black and turkey vultures and compared differences between species and age classes. We found similar element concentrations between juvenile and adult black vultures with the exception of Cu, where levels were higher in juveniles compared to adults. However, we did observe substantial differences in element concentrations between species for both blood and feather samples, with black vultures generally having higher concentrations of most elements. Our data revealed higher element levels in both species compared to toxicity thresholds found in other bird of prey species, such as blood and liver toxicity threshold suggestions for Pb poisoning in Falconiformes. Further, while average contaminant levels were generally low, extreme outliers were observed for some elements, including Pb, suggesting some individuals were exposed to high levels of potentially toxic elements. More research is needed to better understand contaminant exposure in black and turkey vultures across a broader geographic region, as well as elucidate toxicity thresholds and non-lethal impacts of contaminant exposure in these species.

Blood lead concentration in an urban parrot: Nestling Kaka (Nestor meridionalis) demonstrate evidence of exposure to lead via eggs and parental feeding

Lead is a persistent, highly toxic heavy metal known to affect physiological function and survival in birds. Nestlings are particularly at risk as exposure during critical stages of development can result in life-long deficits. Urban environments are increasingly associated with high levels of contamination and lead exposure at the urban-wildlife interface can have significant population health effects on wildlife. Wellington has an established population of Kaka (Nestor meridionalis) and provides the ideal opportunity to study the risks of lead exposure in an urban context. We sampled 139 nestlings over two breeding seasons (2015/16 and 2016/17) and examined concentrations of lead in blood samples. Nestlings were subjected to a clinical and neurological examination. Lead concentrations of egg shells were measured to evaluate maternal transfer of lead to nestlings. Overall, 36.7 % of nestlings showed evidence of lead exposure based on blood lead concentrations, ranging from <3.3μg/dL to 42.9μg/dL, with no detectable clinical signs of toxicity. The pattern of exposure in the majority of nestlings is indicative of exposure from hatch via eggshells and also direct parental feeding of lead following hatch. Lead concentrations in this cohort of Kaka have the potential to contribute to morbidity and mortality in this species. The lack of measurable neurological or physiological deficits associated with lead exposure is suggestive of an innate tolerance to these concentrations of lead in this population. However, the well-described subclinical and persistent effects of lead suggests a need for continued monitoring of this toxicant and its effects on Kaka behaviour and neurodevelopment.

A Global Review of Causes of Morbidity and Mortality in Free-Living Vultures

Vulture species worldwide play a key role in ecosystems as obligate scavengers, and several populations have had precipitous declines. Research on vulture health is critical to conservation efforts including free-living vultures and captive breeding programs, but is limited to date. In this systematic review, we determined the reported causes of free-living vulture species morbidity and mortality worldwide. The most commonly reported cause of mortality was from toxins (60%), especially lead and pesticides, followed by traumatic injury (49%), including collisions with urban infrastructure and gunshot. Neglected areas of research in free-living vulture health include infectious diseases (16%), endocrine and nutritional disorders (6%), and neoplasia (< 1%). Almost half of the studies included in the review were conducted in either Spain or the USA, with a paucity of studies conducted in South America and sub-Saharan Africa. The highest number of studies was on Griffon (Gyps fulvus) (24%) and Egyptian vultures (Neophron percnopterus) (19%), while half of all vulture species had five or fewer studies. Future investigations on free-living vulture health should focus on neglected areas of research, such as infectious diseases, and areas with gaps in the current literature, such as South America, sub-Saharan Africa, and under-studied vulture species.

Major lead exposure from hunting ammunition in eagles from Sweden

Exposure to lead (Pb) from ammunition in scavenging and raptorial birds has achieved worldwide recognition based on incidences of lethal poisoning, but exposure implies also sublethal levels with potential harmful effects. Background and elevated Pb levels in liver from 116 golden eagles (GE, Aquila chrysaetos) and 200 white-tailed sea eagles (WTSE, Haliaeetus albicilla) from Sweden 2003-2011 are here examined, with supporting data from a previous WTSE report and eagle owl (EO, Bubu bubo) report. GE and WTSE display seasonal patterns, with no Pb level exceeding a generally accepted threshold for subclinical effects during summer but strongly elevated levels from October. Fledged juveniles show significantly lower levels than all other age classes, but reach levels found in older birds in autumn after the start of hunting seasons. Pb levels in EO (non-scavenger) show no seasonal changes and indicate no influence from ammunition, and are close to levels observed in juvenile eagles before October. In all, 15% WTSE and 7% GE were lethally poisoned. In areas with high-exposure to hunting ammunition, 24% of WTSE showed lethal Pb levels, compared to 7% in both eagle species from low-exposure areas. Lethal poisoning of WTSE remained as frequent after (15%) as before (13%) a partial ban on use of Pb-based shotgun ammunition over shallow waters (2002). Pb levels increased significantly in WTSE 1981-2011, in contrast to other biota from the same period. A significant decrease of Pb in WTSE liver occurred below a threshold at 0.25 μg/g (dry weight), exceeded by 81% of the birds. Trend patterns in Pb isotope ratios lend further support to this estimated cut-off level for environmental background concentrations. Pb from spent ammunition affects a range of scavenging and predatory species. A shift to Pb-free ammunition to save wildlife from unnecessary harm is an important environmental and ethical issue.

Animal Harms and Food Production: Informing Ethical Choices

Simple Summary

Consideration of animal welfare in food choices has become an influential contemporary theme. Traditional animal welfare views about food have been largely restricted to direct and intentional harms to livestock in intensive animal agriculture settings. However, many harms to animals arising from diverse food production practices in the world are exerted indirectly and unintentionally and often affect wildlife. Here we apply a qualitative analysis of food production by considering the breadth of harms caused by different food production systems to wild as well as domestic animals. Production systems are identified that produce relatively few and relatively many harms. The ethical implications of these findings are discussed for consumers concerned with the broad animal welfare impacts of their food choices.

Abstract

Ethical food choices have become an important societal theme in post-industrial countries. Many consumers are particularly interested in the animal welfare implications of the various foods they may choose to consume. However, concepts in animal welfare are rapidly evolving towards consideration of all animals (including wildlife) in contemporary approaches such as “One Welfare”. This approach requires recognition that negative impacts (harms) may be intentional and obvious (e.g., slaughter of livestock) but also include the under-appreciated indirect or unintentional harms that often impact wildlife (e.g., land clearing). This is especially true in the Anthropocene, where impacts on non-human life are almost ubiquitous across all human activities. We applied the “harms” model of animal welfare assessment to several common food production systems and provide a framework for assessing the breadth (not intensity) of harms imposed. We considered all harms caused to wild as well as domestic animals, both direct effects and indirect effects. We described 21 forms of harm and considered how they applied to 16 forms of food production. Our analysis suggests that all food production systems harm animals to some degree and that the majority of these harms affect wildlife, not livestock. We conclude that the food production systems likely to impose the greatest overall breadth of harms to animals are intensive animal agriculture industries (e.g., dairy) that rely on a secondary food production system (e.g., cropping), while harvesting of locally available wild plants, mushrooms or seaweed is likely to impose the least harms. We present this conceptual analysis as a resource for those who want to begin considering the complex animal welfare trade-offs involved in their food choices.

Foraging behavior, contaminant exposure risk, and the stress response in wild California condors (Gymnogyps californianus)

Wild California condors (Gymnogyps californianus) are frequently exposed to lead via lead-based ammunition ingestion, and recent studies indicate significant exposure to organochlorines (e.g. dichlorodiphenyldichloroethylene (DDE) and polychlorinated biphenyls (PCBs)) for condors feeding on beach-cast marine mammals. We investigated the influence of contaminant exposure on condor glucocorticoid response through comparisons between wild and captive populations and identification of modifiers of glucocorticoid release in wild condors. We assessed the glucocorticoid response to routine trapping and handling events through measurement of plasma corticosterone and urate glucocorticoid metabolites (GCM). Comparison of peak urate GCM levels showed wild condors exhibited higher responses to handling-associated stressors (2300 ± 1400 ng/g dry wt, average ± SD, n = 27) than captive condors (910 ± 490 ng/g dry wt., n = 6, U = 28, p = 0.003). Multiple linear regression models and an information theoretic approach (AIC_c) identified several extrinsic variables (e.g., time captive in flight pen before sample collection) that were negatively associated with plasma corticosterone and urate GCM levels in wild condors, which explained ~25% of glucocorticoid variation. When accounting for these extrinsic variables we found that behavioral variables associated with increased lead and organochlorine exposure risk were positively associated with GCM levels, explaining an additional 15% of glucocorticoid variation among wild condors. Days absent from management area, a variable associated with reduced survival attributed to increased lead exposure risk, had a positive influence on plasma corticosterone levels (β = 53 ± 20 SE) and peak urate GCM levels (β = 1090 ± 586 SE). Years observed feeding on marine mammals, a variable positively associated with DDE and PCB exposure, positively influenced peak urate GCM (β = 1100 ± 520 SE) and the magnitude of GCM response (peak GCM - 1st urate GCM) (β = 1050 ± 500 SE). Our findings suggest that individual propensities for contaminant-associated foraging behaviors predict higher stress-induced glucocorticoid levels in wild condors, and that accounting for variables associated with trapping and handling is essential for assessing the impact of environmental stressors such as contaminants on the condor stress response. As an abnormal glucocorticoid response to stress is associated with reduced reproduction and survival in vertebrates, this work indicates the need for further investigations into the physiological impacts of sub-lethal contaminant exposures in scavenging species worldwide.

Lead in terrestrial game birds from Spain

We analysed exposure to Pb and its relationship with lead-based ammunition in seven species of terrestrial game birds-common woodpigeon (Columba palumbus), rock dove (Columba livia), stock dove (Columba oenas), European turtle-dove (Streptopelia turtur), red-legged partridge (Alectoris rufa), Barbary partridge (Alectoris barbara) and common quail (Coturnix coturnix)-from rural and urban areas in different parts of Spain (Valencia, Castilla-La Mancha, Castilla y León, Madrid, Islas Canarias and Navarra). A total of 530 liver samples were analysed, and the presence of Pb pellets was studied in the crop, gizzard and intestine; the state and appearance of these organs were also analysed. The number of specimens suspected to have ingested Pb shot was 28 (5.6%), and the geometric mean concentration of hepatic Pb was 0.054 μg g^-1 (wet weight, ww). A low percentage of samples (4.8%) were above the abnormal exposure threshold (0.65 μg g^-1 ww), and, in these specimens, renal Pb concentrations were determined. Common woodpigeons and rock doves from Madrid were found to have high concentrations of Pb in their livers, and, so, both species can be considered to be good bioindicators of Pb contamination in rural (common woodpigeons) and urban (rock doves) environments. Partridges bred for hunting may be more prone to ingesting pellets from the environment, a fact that should be taken into account in management decisions.

Heads in the sand: public health and ecological risks of lead-based bullets for wildlife shooting in Australia

Lead (Pb) is a toxic element banned from fuel, paint and many other products in most developed countries. Nonetheless, it is still widely used in ammunition, including rifle bullets, and Pb-based bullets are almost universally used in Australia. For decades, poisoning from Pb shot (shotguns) has been recognised as a cause of disease in waterfowl and Pb shot has been subsequently banned for waterfowl hunting in many jurisdictions. However, the risks posed by Pb-based bullets (rifles) have not been similarly recognised in Australia. Pb-based rifle bullets frequently fragment, contaminating the tissue of shot animals. Consuming this Pb-contaminated tissue risks harmful Pb exposure and, thus, the health of wildlife scavengers (carrion eaters) and humans and their companion animals who consume harvested meat (game eaters). In Europe, North America and elsewhere, the environmental and human health risks of Pb-based bullets are widely recognised, and non-toxic alternatives (e.g. copper-based bullets) are increasingly being used. However, Australia has no comparable research despite widespread use of shooting, common scavenging by potentially susceptible wildlife species, and people regularly consuming shot meat. We conclude that Australia has its collective ‘head in the sand’ on this pressing worldwide One Health issue. We present the need for urgent research into this field in Australia.

Soil pollution at outdoor shooting ranges: Health effects, bioavailability and best management practices

The total lead (Pb) concentrations of the surface soil, sub surface soil, vegetation and surface waters of outdoor shooting ranges are extremely high and above regulatory limits. Lead is dangerous at high concentrations and can cause a variety of serious health problems. Shooters and range workers are exposed to lead dust and can even take Pb dust home to their families while some animals around the shooting range can ingest the Pb bullets. The toxicity of Pb depends on its bioavailability which has been determined to be influenced greatly by the geochemical properties of each site. The bioavailability of Pb in shooting ranges has been found to be higher than other metal contaminated soils probably because of its very low residual Pb (<1%). Despite being an immobile element in the soil, migration of Pb within shooting ranges and offsite has been reported in literature. Best management practices to reduce mobility of Pb in shooting ranges involve an integrated Pb management program which has been described in the paper. The adoption of the non-toxic "green bullet" which has been developed to replace Pb bullets may reduce or prevent environmental pollution at shooting ranges. However, the contaminated soil resulting from decades of operation of several shooting ranges still needs to be restored to its natural state.

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

Lead poisoning, through the ingestion of spent lead gunshot, is an established cause of morbidity and mortality in waterbirds globally, but the thresholds at which blood levels begin to affect the physiology of birds in the wild are less well known. Here we determine the prevalence of lead exposure in whooper swans and, for the first time, identify the level of blood lead associated with initial reductions in body condition. Blood lead elevated above background levels (i.e. >20 μg dL(-1)) was found in 41.7% (125/300) of swans tested. Blood lead was significantly negatively associated with winter body condition when levels were ≥44 μg dL(-1) (27/260 = 10%). Our findings indicating that sub-lethal impacts of lead on body condition occur at the lower end of previously established clinical thresholds and that a relatively high proportion of individuals in this population may be affected, reaffirm the importance of reducing contamination of the environment with lead shot.

Causes of mortality and unintentional poisoning in predatory and scavenging birds in California

Objectives

We documented causes of mortality in an opportunistic sample of golden eagles, turkey vultures and common ravens, and assessed exposure to several contaminants that have been found in carrion and common prey for these species.

Methods

Dead birds were submitted for testing through wildlife rehabilitation centres and a network of wildlife biologists in California from 2007 to 2009.

Results

The leading causes of mortality in this study were collision-related trauma (63 per cent), lead intoxication (17 per cent) and anticoagulant rodenticide poisoning (8 per cent). Elevated liver lead concentration (≥2 µg/g) and bone lead concentration (>6 µg/g) were detected in 25 and 49 per cent of birds tested, respectively. Approximately 84 per cent of birds tested had detectable rodenticide residues. The majority of rodenticide exposure occurred in peri-urban areas, suggesting that retail sale and use of commensal rodent baits, particularly in residential and semi-residential areas in California, may provide a pathway of exposure.

Conclusions

Monitoring anthropogenic causes of mortality in predatory and scavenging bird species provides important data needed to inform on mitigation and regulatory efforts aimed at reducing threats to these populations.