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Lead (Pb) exposure is a widespread wildlife conservation threat. Although commonly associated with Pb-based ammunition from big-game hunting, small mammals (e.g., ground squirrels) shot for recreational or pest-management purposes represent a potentially important Pb vector in agricultural regions. We measured the responses of avian scavengers to pest-shooting events and examined their Pb exposure through consumption of shot mammals. There were 3.4-fold more avian scavengers at shooting fields relative to those at fields with no recent shooting, and avian scavengers spent 1.8-fold more time feeding after recent shooting events. We isotopically labeled shot ground squirrels in the field with an enriched 15N isotope tracer; 6% of avian scavengers sampled within a 39 km radius reflected this tracer in their blood. However, 33% of the avian scavengers within the average foraging dispersal distance of nests (0.6-3.7 km) were labeled, demonstrating the importance of these shooting fields as a source of food for birds nesting in close proximity. Additionally, Pb concentrations in 48% of avian scavengers exceeded subclinical poisoning benchmarks for sensitive species (0.03-0.20 μg/g w/w), and those birds exhibited reduced δ-aminolevulinic acid dehydratase activity, indicating a biochemical effect of Pb. The use of shooting to manage small mammal pests is a common practice globally. Efforts that can reduce the use of Pb-based ammunition may lessen the negative physiological effects of Pb exposure on avian scavengers.

Birds of a number of species have died as a result of lead (Pb) poisoning, including many Steller's sea eagles (Haliaeetus pelagicus) and white-tailed sea eagles (Haliaeetus albicilla) in Hokkaido, the northernmost island of Japan. To address this issue, the use of any type of Pb ammunition for hunting of large animals was prohibited in Hokkaido in 2004. However, Pb poisoning is still being reported in this area, and there are few regulations regarding the use of Pb ammunition in other parts of Japan, where it has been reported that eagles and water birds have been exposed to Pb. This study was performed to accurately determine the current level of Pb exposure of birds found dead in the field or dead in the wild bird centers in Japan (June 2015-May 2018) and to identify the sources of Pb. Pb exposure was found to still be occurring in raptors and water birds in various parts of Japan. Twenty-six point five % and 5.9% of the recorded deaths of Steller's sea eagles and white-tailed sea eagles, respectively, were found to have been poisoned by Pb. In addition, Pb isotope ratio analysis showed that both Pb rifle bullets and Pb shot pellets cause Pb exposure in birds, and these endangered eagles are also exposed to Pb in Hokkaido due to the illegal use of Pb ammunition. Changing to Pb-free ammunition, such as copper (Cu) rifle bullets, steel shot pellets, or bismuth shot pellets, will be essential for the conservation of avian species in Japan.

The ingestion of lead (Pb) shot pellets is a well-known cause of avian mortality, but exposure of birds to Pb may have other sublethal effects that can affect population sustainability. One of these effects is the alteration of the immunological status. Pb can affect most components of the avian immune system and imbalance the relationship among them. Pb exposure typically alters the ratio between T- and T-type responses mounted by different classes of T-lymphocytes, causing the depression of the T responses that are associated with cell-mediated immunity. Immunodepressing effects of Pb on birds are observed at blood levels above 50 μg dL, but developing birds show immunodepressing effects at much lower concentrations (> 10 μg dL). Impacts of Pb on the avian immune system also relate to reduced resistance to infection. We review immunotoxic effects of Pb on birds affected by shot ingestion as well as by other sources of exposure to this element., Part of the information included in this review was compiled as part of a research project funded by the Spanish Ministry of Science and Innovation (grant CGL2010-17030) and included in the PhD Thesis of NVC, who benefited from an FPI fellowship of the Spanish Ministry of Science and Innovation (ref. BES-2011-045670).

Game meat may contain elevated concentrations of lead especially if lead-containing ammunition is used for hunting. Then a health risk is possible for consumer groups with high game meat intake. The lead concentrations in three edible parts (marketable meat from the area close to the wound channel, saddle and haunch) of meat from red deer (Cervus elaphus) between animals hunted either with lead or non‑lead ammunition were compared. Furthermore, lead levels in game meat of lead-shot red deer were compared with those of lead-shot roe deer and lead-shot wild boar. Ninety red deer were shot and killed in the context of this study (64 with lead and 26 with non‑lead ammunition). Since the lead concentration for a number of the samples was below the limit of detection or the limit of quantification, statistical methods for left-censored data were applied. The median concentrations of lead in game meat did not differ significantly between lead shot and non‑lead shot animals. However, when we analyzed the more elevated lead concentrations, they were significantly higher in edible parts of animals shot with lead ammunition than non-lead ammunition. The highest concentrations were found in samples from edible meat from the area close to the wound channel (max 3442 mg Pb/kg), followed by the saddle (max 1.14 mg Pb/kg) and with the lowest levels in the haunch (max 0.09 mg Pb/kg). A comparison of game species revealed that the lead concentration in haunch and saddle of lead shot red deer was higher than in the corresponding samples of lead shot roe deer. Our results have shown that by the use of non-lead ammunition, a significant reduction of the lead concentration especially in edible parts near the wound channel is possible.

Studies on ballistic trauma to the ribs and thorax, cranium, and long bones demonstrate the potential of obtaining a bullet caliber from an entrance wound. In order to validate prior research on caliber estimation in bone tissue and assess the viability of bullet type determination based on the macroscopic evidence at the entrance wound, thirty fleshed pork (Sus scrofa) shoulders (humeri) were shot with either lead or copper jacketed bullets in one of three calibers; 0.22, 9 mm, or 0.38. Overall, our findings are consistent with previous research indicating that calibers can be grouped into "small" and "large" categories. Bullet type, lead or copper jacket, can be ascertained based on cortical flaking and the analysis of materials deposited around the entry wound. The addition of this evidence holds value in cases where no firearm or ballistic evidence is recovered from a crime scene.

In response to the health threats posed by toxic lead to humans, scavenging wildlife and the environment, there is currently a focus on transitioning from lead-based to lead-free bullets for shooting of wild animals. We compared efficiency metrics and terminal ballistic performance for lead-based and lead-free (non-lead) bullets for aerial shooting of wild pigs (Sus scrofa) in eastern Australia. Ballistic testing revealed that lead-based and lead-free bullets achieved similar performance in precision and muzzle kinetic energy (E0) levels (3337.2 J and 3345.7 J, respectively). An aerial shooting trial was conducted with wild pigs shot with one type of lead-based and one type of lead-free bullets under identical conditions. Observations were made from 859 shooting events (n = 430 and 429 respectively), with a sub-set of pigs examined via gross post-mortem (n = 100 and 108 respectively), and a further sub-set examined via radiography (n = 94 and 101 respectively). The mean number of bullets fired per pig killed did not differ greatly between lead-based and lead-free bullets respectively (4.09 vs 3.91), nor did the mean number of bullet wound tracts in each animal via post-mortem inspection (3.29 vs 2.98). However, radiography revealed a higher average number of fragments per animal (median >300 vs median = 55) and a broader distribution of fragments with lead-based bullets. Our results suggest that lead-based and lead-free bullets are similarly effective for aerial shooting of wild pigs, but that the bullet types behave differently, with lead-based bullets displaying a higher degree of fragmentation. These results suggest that aerial shooting may be a particularly important contributor to scavenging wildlife being exposed to lead and that investigation of lead-free bullets for this use should continue.

As a consequence of the toxicological lead characteristics, a reduction of its exposure should consider all sources. Game meat might contain elevated levels of lead due to the use of lead ammunition. The aim of the present study was to investigate the effects of acidic marination on the bioavailability of ammunition-derived lead in game meat (Roe deer), using the growing pig as an animal model. Furthermore, the study should provide evidence that the large-area scattering of lead particles leads to noticeable differences in the individual lead intake per game meat portion. Pigs of group A (n 7) received lead-shot game meat, which was cooked in water. Pigs of group B (n 7) received lead-shot game meat, which was first marinated (wine and vinegar) and then cooked. The lead content of both game meat preparations was equal with 0⋅77–0⋅79 mg Pb/portion. Pigs of group C (n 4) received lead-free game meat, which was also marinated and cooked. Additionally, lead acetate was administered intravenously to group D pigs (n 4). Blood samples were taken on elevated time points before and after game meat intake/i.v.-application. The acidic marination increased the bioavailability of orally ingested lead, resulting in significantly higher blood lead concentrations. The bioavailability of lead was 2⋅7 % when game meat was just cooked and 15 % when the meat was marinated before. The considerable variation of the individual blood lead concentrations suggests that an inhomogeneous distribution of ammunition-derived lead particles (in terms of size and number) causes individually non-comparable lead intakes from the consumption of game meat.

Lead poisoning from spent ammunition is known to affect many avian species. Birds of prey ingest lead when feeding on game shot with lead gunshot or bullets. Raptors with scavenging habits are particularly vulnerable to ingesting lead in areas with intensive hunting and are good indicators of the risk of poisoning from lead ammunition. To assess how much facultative and obligate avian scavengers suffer lead contamination in south-central Europe, between 2005 and 2019 we collected and analysed 595 tissue samples from 252 carcasses of 4 species (golden eagle, bearded vulture, griffon vulture, cinereous vulture). Lead concentrations in organs showed a similar pattern across species with long and small bones revealing the highest median values (5.56 and 6.8 mg/kg w.w., respectively), the brain the lowest (0.12), and the liver and kidney the intermediate (0.47 and 0.284). Overall, 111 individuals (44.0%) had lead concentrations above background thresholds in at least one tissue (i.e. >2 mg/kg w.w. in soft tissues, >8.33 in bone) and 66 (26.2%) had values indicating clinical poisoning (>6 mg/kg w.w. in liver, >4 in kidney, >16.6 in bone). Tissue lead concentrations and incidence of clinical and sub-clinical poisoning were higher in golden eagles and griffon vultures than in bearded and cinereous vultures, likely due to different feeding habits. In all species we found a rapid increase in lead values with age, but differences between age classes were significant only in the golden eagle. Birds with lead fragments in their digestive tract, as detected by X-rays, had higher median lead concentrations, suggesting that hunting ammunition is the main source of lead poisoning. Our results imply that lead impacts the demography of these long-lived species with delayed sexual maturity and low reproduction rate. A rapid transition towards lead-free bullets and gunshot is therefore required across Europe.

Lead contamination is a widely recognised conservation problem for raptors worldwide. There are a number of studies in individual raptor species but those data have not been systematically evaluated to understand raptor-wide lead exposure and effects at a pan-European scale. To critically assess the extent of this problem, we performed a systematic review compiling all published data on lead in raptors (1983–2019) and, through a meta-analysis, determined if there was evidence for differences in exposure across feeding traits, geographical regions, between hunting and non-hunting periods, and changes over time. We also reviewed the impact of lead on raptors and the likely main source of exposure. We examined 114 studies that were unevenly distributed in terms of time of publication and the countries in which studies were performed. Peer-reviewed articles reported data for 39 raptor species but very few species were widely monitored across Europe. Obligate (vultures) and facultative scavengers (golden eagle, common buzzard and white-tailed sea eagle) accumulated the highest lead concentrations in tissues and generally were the species most at risk of lead poisoning. We found no evidence of a spatial or decadal trend in lead residues, but we demonstrated that high lead blood levels relate to hunting season. Exposure at levels associated with both subclinical and lethal effects is common and lead from rifle bullets and shot is often the likely source of exposure. Overall, our review illustrates the high incidence and ubiquity of lead contamination in raptors in Europe. However, we did not find studies that related exposure to quantitative impacts on European raptor populations nor detailed studies on the impact of mitigation measures. Such information is urgently needed and requires a more harmonised approach to quantifying lead contamination and effects in raptors across Europe.

Many studies have used grit (in the form of lead (Pb) pellets) presence in avian gizzards as an indicator of Pb shot exposure. However, due to nearly complete pellet absorption in gizzards or rapid passage of pellets, the absence of Pb shot presence in a gizzard does not confirm lack of Pb shot exposure. This study provides the basis for an additional technique to identify if elevated tissue Pb concentration is due to Pb shot exposure. Bioaccessibility of Pb and trace elements (Sb, As, and Sn) present in Pb shot were quantified to determine if any of these elements would be useful as a secondary marker of Pb shot exposure. An avian physiologically based extraction test (PBET) was used to determine pellet dissolution rate and bioaccessible concentrations of Pb, Sb, As, and Sn in a simulated gizzard environment. Of the three trace elements, only Sb concentrations (44-302 μg/mL) extracted into the gizzard solution were greater than environmental background levels (US soil average 0.48 μg/g); thus, no natural source likely provides this amount of Sb. Therefore, there is evidence that Sb can be extracted from Pb shot in bird gizzards at detectable concentrations (above natural background). While further studies are needed to delineate the mechanisms of absorption and distribution, this study lends credence to the hypothesis that Sb may be a useful marker of Pb shot exposure in biological tissues, particularly when Pb pellets are not present nor observed in avian tissues.

The widespread use of lead (Pb) shot in shooting activities, including at former shooting ranges, continues to pose environmental risks. The La Crosse River Marsh (located in Wisconsin, USA) is a biologically diverse urban riparian wetland with a legacy of Pb-contaminated sediment resulting from its use as a trap shooting range from 1929-1963. Within the shot fall zone, shot densities exceed 43,000 pellets/m

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.

Denmark was the first European country to completely ban lead shot for hunting and target shooting. This paper reviews the process behind this phase-out to document its history, successes, and pitfalls, and to make the Danish experiences accessible for the benefit of other countries, authorities, and stakeholders who face nature management challenges implementing similar change. A review of the content of magazines published by the three hunters’ organizations during the 1978–1992 transition period was carried out, to assess the general discourse and identify the primary concerns and attitudes during the phase-out of lead shot for hunting in Denmark. Hunters were initially negative towards the change. Resistance was driven by concern about the quality, safety issues, and expensive cost of non-toxic alternatives, compounded by lack of organizational leadership and tensions between stakeholders. As a result of the widening appreciation of the environmental effects of dispersed lead shot and the introduction of new generations of alternative shot types, hunter attitudes became positive and constructive. Change need not pose an obstruction to continued hunting opportunity. On the contrary, it is believed that the value from the enhancement of the public image of hunters resulting from the reduction in the environmental dispersal of a recognized contaminant is of paramount importance for the long-term political sustainability of hunting.

The toxicity of lead has been known for a long time, and no safe uptake level can be derived for humans. Consumers' intake via food should therefore be kept as low as possible. Game meat can contain elevated levels of lead due to the use of lead ammunition for hunting. A risk assessment conducted in 2010 by the German Federal Institute for Risk Assessment including various consumption scenarios revealed a possible health risk for extreme consumers of game meat hunted with lead ammunition (i.e. hunters and members of hunters' households). Babies, infants, children and women of childbearing age were identified as vulnerable group with regards to the developmental neurotoxicity of lead. It was noted, that a sound data base was required in order to refine the assessment. Therefore, the research project "Safety of game meat obtained through hunting" (LEMISI) has been conducted in Germany, with the aims of determining the concentrations of lead (as well as of copper and zinc) brought into the edible parts of game meat (roe deer (Capreolus capreolus) and wild boar (Sus scrofa)) due to using either lead or non-lead hunting ammunition, whilst concurrently taking geogenic (i.e. "background") levels of lead into account. Compared to non-lead ammunition, lead ammunition significantly increased lead concentrations in the game meat. The use of both lead and non-lead ammunition deposited copper and zinc in the edible parts of game meat, and the concentrations were in the range of those detected regularly in meat of farm animals. For the average consumer of game meat in Germany the additional uptake of lead only makes a minor contribution to the average alimentary lead exposure. However, for consumers from hunters' households the resulting uptake of lead-due to lead ammunition-can be several times higher than the average alimentary lead exposure. Non-lead bullets in combination with suitable game meat hygienic measures are therefore recommended in order to ensure "state of the art consumer health protection".

In European wetlands, at least 40 bird species are exposed to the risk of lead poisoning caused by ingestion of spent lead gunshot. Adopting a methodology developed in North America, we estimated that about 700,000 individuals of 16 waterbird species die annually in the European Union (EU) (6.1% of the wintering population) and one million in whole Europe (7.0%) due to acute effects of lead poisoning. Furthermore, threefold more birds suffer sub-lethal effects. We assessed the economic loss due to this lead-induced mortality of these 16 species by calculating the costs of replacing lethally poisoned wild birds by releasing captive-bred ones. We assessed the cost of buying captive-bred waterbirds for release from market surveys and calculated how many captive-bred birds would have to be released to compensate for the loss, taking into account the high mortality rate of captive birds (72.7%) in the months following release into the wild. Following this approach, the annual cost of waterbird mortality induced by lead shot ingestion is estimated at 105 million euros per year in the EU countries and 142 million euros in the whole of Europe. An alternative method, based upon lost opportunities for hunting caused by deaths due to lead poisoning, gave similar results of 129 million euros per year in the EU countries and 185 million euros per year in the whole of Europe. For several reasons these figures should be regarded as conservative. Inclusion of deaths of species for which there were insufficient data and delayed deaths caused indirectly by lead poisoning and effects on reproduction would probably increase the estimated losses substantially. Nevertheless, our results suggest that the benefits of a restriction on the use of lead gunshot over wetlands could exceed the cost of adapting to non-lead ammunition.

Lead (Pb) represents a serious threat to wildlife and ecosystems. The aim of this study was to examine the subcellular effects of dietary Pb pellet ingestion on mallard (Anas platyrhynchos) livers. After ingestion of a single Pb shot (LS4 size class: 0.177 ± 0.03 g) in 41 mallard ducks (22 males and 19 females) versus 10 controls (5 males and 5 females), all 7-week old, a morphologic study was conducted by TEM (transmission electron microscopy) of liver at the subcellular level. The results in treated mallards showed at a magnification of 2500 X that hepatic parenchyma was altered as evidenced by intralysosomal electron-dense deposits, which are compatible with Pb deposits. Further, at a higher magnification (15,000 X) in both genders, deterioration of mitochondria was observed in which the crests and, to a lesser extent, outer membrane were lysed. While the rough endoplasmic reticulum was fragmented, intracytoplasmic electron-dense material compatible with Pb deposits was maximally visible, thereby underscoring the deeply destructive effect of this metal on the subcellular architecture of the liver. In addition, applying an optimized and validated method in a clean room using electrothermal atomic absorption spectrophotometer (ETAAS) with Zeeman background correction, the objective was to improve and refine certain indispensable measurements pertaining to Pb impregnation in tissues other than liver such as kidneys, bones, and feathers of mallards. Data demonstrated show that compared with controls, Pb accumulation increases significantly, not only in the liver (3-fold), but also in the bones and the feathers (14-fold). No significant difference was noted between males and females. Bearing in mind the marked subcellular toxicity attributed to Pb, this study reinforces present-day arguments advocating limitation of game consumption.

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.

The aim of this study was to examine the contamination of game meat with copper and zinc and establish whether the use of alternative (non-lead) ammunition can lead to higher or unsafe levels of copper and zinc in the meat of roe deer, wild boar and red deer. The research project "Safety of game meat obtained through hunting" (LEMISI) was conducted in Germany with the purpose of examining the entry of lead as well as copper and zinc into the meat of hunted game when using either lead or non-lead ammunition. The outcome of this study shows that the usage of both lead-based ammunition and alternative non-lead ammunition results in the entry of copper and zinc into the edible parts of the game. Using non-lead ammunition does not entail dangerously elevated levels of copper and zinc, so replacing lead ammunition with alternative ammunition does not introduce a further health problem with regard to these metals. The levels of copper and zinc in game meat found in this study are in the range found in previous studies of game. The content of copper and zinc in game meat is also comparable to those regularly detected in meat and its products from livestock (pig, cattle, sheep) for which the mean human consumption rate is much higher. From the viewpoint of consumer health protection, the use of non-lead ammunition does not pose an additional hazard through copper and zinc contamination. A health risk due to the presence of copper and zinc in game meat at typical levels of consumer exposure is unlikely for both types of ammunition.

Background Non-lead hunting ammunition is an alternative to bullets that contain lead. The use of lead ammunition can result in severe contamination of game meat, thus posing a health risk to consumers. With any kind of ammunition for hunting, the terminal effectiveness of bullets is an animal welfare issue. Doubts about the effectiveness of non-lead bullets for a humane kill of game animals in hunting have been discussed. The length of the escape distance after the shot has been used previously as an indicator for bullet performance. Objective The object of this study was to determine how the bullet material (lead or non-lead) influences the observed escape distances. Methods 1,234 records of the shooting of roe deer (Capreolus capreolus) and 825 records of the shooting of wild boar (Sus scrofa) were evaluated. As the bullet material cannot be regarded as the sole cause of variability of escape distances, interactions of other potential influencing variables like shot placement, shooting distance, were analyzed using conditional regression trees and two-part hurdle models. Results The length of the escape distance is not influenced by the use of lead or non-lead ammunition with either roe deer or wild boar. With roe deer, the length of the escape distance is influenced significantly by the shot placement and the type of hunting. Increasing shooting distances increased the length of the escape distance. With wild boar, shot placement and the age of the animals were found to be a significant influencing factor on the length of the escape distance. Conclusions The length of the escape distance can be used as an indicator for adequate bullet effectiveness for humane killings of game animals in hunting.Non-lead bullets already exist which have an equally reliable killing effect as lead bullets.

Avian scavengers that typically include game birds and mammals in their diets are at risk of lead poisoning from ingestion of carcasses with fragmented or residual lead ammunition that is used in hunting. Thus, lead may be one of the threats that the griffon vulture ( Gyps fulvus ) faces in the Iberian Peninsula and particularly in Portugal, where their conservation status is considered to be near-threatened. This is the first report that details 3 cases of lead poisoning, associated with the ingestion of lead shot, in adult female griffon vultures found in the Iberian Peninsula. The birds were found prostrate and immediately transferred to a wildlife rehabilitation center, where they died within 24 hours after supportive treatment. Necropsy and histopathologic examinations were done in 2 birds and metal analyses were done in all birds to determine the birds' causes of death. In one vulture, 9 uneroded lead pellets were recovered from the stomach, and moderate to severe hemosiderosis was seen histologically in the liver, lungs, and kidneys. Diagnosis of lead poisoning was confirmed by results of metal analyses, which revealed extremely high lead concentrations in blood (969-1384 μg/dL), liver (309-1077 μg/g dry weight), and kidneys (36-100 μg/g dry weight) for all 3 vultures. To prevent lead poisoning in vultures and preserve their populations in the Iberian Peninsula, more resources are needed for diagnosis and treatment of wildlife in rehabilitation centers, new regulations enabling the abandonment of fallen stock in the field must be approved, and lead ammunition must be prohibited in big-game hunting.

Recreational ground squirrel shooting is a popular activity throughout the western United States and serves as a tool for managing ground squirrel populations in agricultural regions. Belding's ground squirrels (Spermophilus beldingi) are routinely shot in California, Nevada, and Oregon across habitats that overlap with breeding avian scavengers. Ground squirrels shot with lead (Pb)-based bullets may pose a risk to avian scavengers if they consume carcasses containing Pb fragments. To assess the potential risk to breeding avian scavengers we developed a model to estimate the number, mass, and distribution of Pb fragments in shot ground squirrels using radiographic images. Eighty percent of shot carcasses contained detectible Pb fragments with an average of 38.6 mg of Pb fragments. Seven percent of all carcasses contained Pb fragment masses exceeding a lethal dose for a model raptor nestling (e.g. American kestrel Falco sparverius). Bullet type did not influence the number of fragments in shot ground squirrels, but did influence the mass of fragments retained. Belding's ground squirrels shot with .17 Super Mag and unknown ammunition types contained over 28 and 17 times more mass of Pb fragments than those shot with .22 solid and .22 hollow point bullets, respectively. Ground squirrel body mass was positively correlated with both the number and mass of Pb fragments in carcasses, increasing on average by 76% and 56% respectively across the range of carcass masses. Although the mass of Pb retained in ground squirrel carcasses was small relative to the original bullet mass, avian scavenger nestlings that frequently consume shot ground squirrels may be at risk for Pb-induced effects (e.g., physiology, growth, or survival). Using modeling efforts we found that if nestling golden eagles (Aquila chrysaetos), red-tailed hawks (Buteo jamaicensis), and Swainson's hawks (B. swainsoni) consumed shot ground squirrels proportionately to the nestling's mass, energy needs, and diet, 100% of the nestling period would exceed a 50% reduction in delta-aminolevulinic acid dehydratase production threshold, the last 13-27% of the nestling stage would exceed a reduced growth rate threshold, but no nestlings would be expected to exceed a level of Pb ingestion that would be lethal.

Little is known about the magnitude of the effects of lead shot ingestion alone or combined with poisons (e.g., in bait or seeds/granules containing pesticides) on population size, growth, and extinction of non-waterbird avian species that ingest these substances. We used population models to create example scenarios demonstrating how changes in these parameters might affect three susceptible species: grey partridge (Perdix perdix), common buzzard (Buteo buteo), and red kite (Milvus milvus). We added or subtracted estimates of mortality due to lead shot ingestion (4–16% of mortality, depending on species) and poisons (4–46% of mortality) reported in the UK or France to observed mortality of studied populations after models were calibrated to observed population trends. Observed trends were decreasing for partridge (in continental Europe), stable for buzzard (in Germany), and increasing for red kite (in Wales). Although lead shot ingestion and poison at modeled levels did not change the trend direction for the three species, they reduced population size and slowed population growth. Lead shot ingestion at modeled rates reduced population size of partridges by 10%, and when combined with bait and pesticide poisons, by 18%. For buzzards, decrease in mean population size by lead shot and poisons combined was much smaller (≤ 1%). The red kite population has been recovering; however, modeled lead shot ingestion reduced its annual growth rate from 6.5% to 4%, slowing recovery. If mortality from poisoned baits could be removed, the kite population could potentially increase at a rapid annual rate of 12%. The effects are somewhat higher if ingestion of these substances additionally causes sublethal reproductive impairment. These results have uncertainty but suggest that declining or recovering populations are most sensitive to lead shot or poison ingestion, and removal of poisoned baits can have a positive impact on recovering raptor populations that frequently feed on carrion.

Historically, lead poisoning through lead shot ingestion was one of the largest health issues affecting waterfowl in North America. Lead shot was banned for use in waterfowl hunting in the US in 1991 and was banned in Canada in 1997. However, biologists need to understand how, and if, lead shot remaining in the environment will continue to impact waterfowl. Our goal was to estimate lead and nontoxic shot consumption by female Northern Pintails (Anas acuta) wintering along the Texas coast. We found shot or metal fragments (or both) in the gizzards of 39 (17%) of 227 female Northern Pintails collected along the Texas coast. Of these, lead shot was found in seven gizzards, steel shot was found in 24 gizzards, and other metal and fragments were found in 20 gizzards. Some females consumed multiple shot types. Overall, shot (lead and nontoxic combined) ingestion rates were similar to those found prior to the lead shot ban in Texas (14%) and Louisiana (17%); however, lead shot ingestion rates were considerably lower, suggesting that it is becoming less available over time. All Northern Pintails that had lead shot in their gizzards were collected from coastal habitats. While it seems that lead shot ingestion by Northern Pintails has decreased since the ban was put in place, monitoring lead shot ingestion rates from different regions will provide insight into its availability in different habitats and under various environmental conditions.