Nontoxic Shot Research Articles

Shot Ingestion by Wintering Female Northern Pintails (Anas acuta) in the Texas Coastal Plain, 2012–14

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.

Switch to non-toxic shot in the Camargue, France: effect on waterbird contamination and hunter effectiveness

The use of lead shot for wildfowling is a severe threat to waterbirds through ingestion of toxic lead pellets. Consequently, lead shot has been banned in many countries since the late 1990s and on Tour du Valat estate since 1994 (Camargue, France). An experimental study was undertaken to check if hunters would habituate to this new type of cartridge and consequently improve their effectiveness (average number of shots per bagged animal), assess the factors influencing effectiveness, and assess the trend of contamination in shot waterbirds and the estate sediment. From 1995 to 2005, we monitored hunting bags, spent cartridges, and the gizzards of shot ducks. Using generalized mixed effect models, we assessed the factors influencing hunter effectiveness. Instances of non-toxic pellets in duck gizzards increased, probably as a result of rapid accumulation in the sediments. We estimated that between 1995 and 2005, the lead shot ban spared 456 kg of lead from entering 403 ha of temporary marshes and avoided the contamination of 8 % of the ducks foraging on Tour du Valat. After 11 years of hunting with non-toxic shot, there was unexpectedly no clear pattern in trends of individual effectiveness among hunters. Hunter effectiveness was instead positively influenced by game abundance and hunter assiduity and negatively influenced by wind and number of shots, suggesting a lassitude effect. Our results suggest crippling loss can be reduced through regular practice, self-limitation of shooting intensity to below 20 shots to avoid lassitude effects, and self-limitation of shooting distance under strong wind conditions.

Poisoning from lead gunshot: still a threat to wild waterbirds in Britain

Lead is a highly toxic metal known to be an important cause of morbidity and mortality in waterbirds and terrestrial birds worldwide. The risk to birds of poisoning from lead has resulted in the introduction of legislation in many countries, such as UK restrictions on the use of lead in angling weights and lead gunshot. In this study, we examined data on current and historical trends in lead poisoning in British waterbirds and related these to the introduction of legislation restricting the use of lead. Our results indicate that lead poisoning has continued to affect a wide range of British waterbirds long after legal restrictions were introduced. Elevated levels of lead (i.e. >20.0 μg/dL) were found in the blood of 34 % (n = 285) of waterbirds tested at four sites in Britain during the 2010/2011 winter and accounted for the deaths of at least 10.6 % (n = 2,365) of waterbirds recovered across Britain between 1971 and 2010 and 8.1 % (n = 1,051) between 2000 and 2010, with lead gunshot being the most likely source of poisoning. The proportion of birds dying from lead poisoning in England did not vary significantly after the introduction of legislation, accounting for 13.7 % of non-infectious causes of death between 1971 and 1987 (n = 204), 20.8 % (n = 360) between 1988 and 1999 and 11.8 % (n = 423) between 2000 and 2010, despite a significant change in lead-related mortality in mute swans found during the same time period, 25 % (n = 12) between 1971 and 1987, 4.6 % (n = 65) between 1988 and 1999 and 2 % (n = 100) between 2000 and 2010. Existing legislation needs review and extension to ensure the delivery of international commitments and a broad-scale transition to the use of non-toxic shot and angling materials in all environments.

Environment: Lead stymies condor comeback: Birds unlikely to rebound fully without shift to nontoxic shot

Environment: Lead stymies condor comeback: Birds unlikely to rebound fully without shift to nontoxic shot

Ingestion of Lead and Nontoxic Shot by Green-winged Teal (Anas crecca) and Northern Shovelers (Anas clypeata) from the Mid-Gulf Coast of Texas, USA

Ninety-eight Green-winged Teal (Anas crecca) and 84 Northern Shoveler (Anas clypeata) gizzards were examined for ingested shot. One Northern Shoveler had lead and three had steel shot; 24 teal and 17 shovelers had composite nontoxic shot or nonlead metal fragments. Prevalence of ingested lead appears minimal and consistent with other studies conducted after lead-shot bans.

Bone lead levels and lead isotope ratios in red grouse from Scottish and Yorkshire moors

Leg and foot bones of adult and juvenile red grouse ( Lagopus lagopus scoticus) were collected from hunter-shot birds on two Scottish estates (Glendye and Invermark) and one Yorkshire estate in September, 2003. The lead content of bones was measured by atomic absorption spectrophotometry, and corresponding stable lead isotopes (Pb 204, 206, 207, 208) by inductively coupled plasma mass spectrometry. At the Glendye ( N = 111) and Invermark ( N = 85) estates, relatively few birds (5.4% and 3.5%, respectively) had highly elevated bone lead concentrations (> 20 µg/g dry weight). In bones of these highly exposed birds, a combination of Pb 206:Pb 207 and Pb 208:Pb 207ratios was consistent with ingestion of lead gunshot available in Europe. By contrast, Yorkshire grouse experienced a high incidence (65.8%) of bone lead > 20 µg/g. The Pb 206:Pb 207 and Pb 208:Pb 207ratios in bones of these highly exposed birds were consistent with a combined exposure to ingested lead gunshot and lead from galena mining in the region. Lead isotope ratios also indicated that lead from UK gasoline combustion and fallout from atmospheric particles was not a likely source of elevated lead in bones of either Scottish or Yorkshire grouse. Suggested management options for the three moors include adopting nontoxic shot for all game shooting on the estates, allowing heather ( Calluna vulgaris) vegetation to grow tall in lead shot fall-out zones to reduce physical access to high densities of lead shot already present, and provision of calcareous grit across moors to reduce lead assimilation from all ingested sources of lead.

Incidence of Artifact Ingestion in Mute Swans and Tundra Swans on the Lower Great Lakes, Canada

Although lead poisoning is common in swans, no information exists on the prevalence of lead artifact ingestion in swans using the lower Great lakes (LGL). We examined artifact ingestion (lead and non-toxic) in Mute Swans Cygnus olor and Tundra Swans Cygnus columbianus collected on the LGL in Ontario (1999–2003) following the 1999 ban on use of lead shot for waterfowl hunting in Canada. A larger proportion of Mute Swans (19.8% of 243 birds) contained artifacts than did Tundra Swans (6.5% of 77 birds), possibly due to the fact that Mute Swans feed exclusively in aquatic habitats. Overall, 14% of Mute Swans contained nontoxic shot, 6% contained lead shot and 1.6% contained fishing tackle; 4% of Tundra Swans contained non-toxic shot and 2.6% contained lead shot. Adult Mute Swans (22.7%) had a higher incidence of artifact ingestion than did cygnets (8.9%), but there were no age-related differences in Tundra Swans. No sex-related differences in artifact ingestion were detected in either species. Given the overall frequency of shot ingestion in Mute Swans (20% of birds), lead toxicosis probably was a significant mortality factor for this species on the LGL before the lead shot ban. As only 1.6% of Mute Swans and no Tundra Swans contained any form of fishing tackle, angling related injuries and mortalities are likely lower in the LGL than has been reported for swans in Europe. Presently, lead toxicosis is likely having a low to moderate effect on Mute Swans and a minimal effect on Tundra Swans on the LGL.

Shot Ingestion in Scaup on the Lower Great Lakes After Nontoxic Shot Regulations in Canada

Use of lead shot for waterfowl hunting was banned in the United States in 1991 to reduce the incidence of lead toxicosis in waterfowl. In 1999 Canada implemented a similar ban. The lower Great Lakes (LGL) are important migratory areas for greater (Aythya marila) and lesser scaup (A. affinis). Prior to the implementation of the Canadian ban, 11% and 8% of greater and lesser scaup harvested in the LGL, respectively, had ingested lead shot. We collected greater and lesser scaup on the Canadian side of lakes Erie, Ontario, and St. Clair during autumn 1999 and spring 2000 to determine if lead shot ingestion declined 1 year after the ban in Canada. There were no intraspecific (lake, season, sex, or age) or interspecific differences in proportion of birds containing ingested shot. Overall, only 0.6% of birds (n = 4 of 722) contained lead shot and only 3.1% contained nontoxic shot. The low frequency of toxic relative to nontoxic shot ingestion suggests that shot may quickly become inaccessible to scaup on lacustrine areas of the Great Lakes. Thus, the risk of lead toxicosis to scaup migrating through the LGL appears low at this time. Pre- and postban differences in overall ingestion frequencies (8–11% vs. 3.7%) suggests that preban numbers may have been biased (elevated) because lead shot ingestion can increase harvest susceptibility. However, recent scaup dietary shifts may also have contributed to overall declines in shot consumption. Low postban lead shot ingestion may also be indicative of high hunter compliance with nontoxic shot regulations in Canada.

EPIDEMIOLOGIC INVESTIGATION OF LEAD POISONING IN TRUMPETER AND TUNDRA SWANS IN WASHINGTON STATE, USA, 2000–2002

An observational study was conducted to determine the proportionate mortality of wild trumpeter (Cygnus buccinator) and tundra (Cygnus columbianus columbianus) swans that died during the winters of 2000-02 in northwestern Washington State, USA. Among 400 swans necropsied, 81% were lead poisoned (302/365 trumpeter swans; 20/35 tundra swans). Mortality started in mid-November and peaked from late December through mid-February; swan mortality that was not associated with lead poisoning was uniformly lower throughout the winter months. Lead poisoning was 24 times more likely to be the cause of death in swans found in Whatcom County compared to swans found in other locations in northwestern Washington State (95% CI: 12.7, 47.0). Mortality attributable to lead poisoning was twice as likely in adults as in juveniles (95% CI: 1.0, 4.2). Aspergillosis was documented in 62 trumpeter and two tundra swans, including 37 swans in which mortality was caused by lead poisoning. Males were twice as likely as females to have aspergillosis (95% CI: 1.1, 3.8). Traumatic injuries were documented in 37 trumpeter and seven tundra swans, including seven trumpeter swans with concurrent lead poisoning. Dead swans found outside Whatcom County were four times more likely to have traumatic injuries compared to those found in Whatcom County (95% CI: 1.6, 10.0). Overall, lead-poisoned swans were significantly less likely to have concurrent aspergillosis or traumatic injuries. There was no apparent association between grit ingestion (total mass or mass categorized by size) and lead poisoning or number of lead shot. Not surprisingly, lead-poisoned swans were more likely to have one or more lead shot compared to swans that died from other causes (OR 294; 95% CI: 92, 1,005); lead-poisoned swans were also more likely to have one or more nontoxic shot compared to swans that were not poisoned (OR 63; 95% CI: 19, 318). The source(s) of shot are unknown but likely are in or near Whatcom County, Washington.

Acute Lead Toxicosis in Mourning Doves

Previous research has suggested that free-ranging mourning doves (Zenaida macroura) may ingest spent lead pellets, succumb to lead toxicosis, and die in a relatively short time (i.e., an acute lead toxicosis hypothesis). We tested this hypothesis by administering 157 captive mourning doves 2–24 lead pellets, monitoring pellet retention and short-term survival, and measuring related physiological characteristics. During the 19- to 21-day posttreatment period, 104 doves that received lead pellets died (deceased doves) and 53 survived (survivors); all 22 birds in a control group survived. Within 24-hr of treatment, blood lead levels increased almost twice as fast for deceased doves compared to survivors (F1,208 = 55.49; P < 0.001). During the first week, heterophil:lymphocyte (H:L) ratios increased twice as fast for deceased doves than with survivors (F1,198 = 23.14, P < 0.001). Posttreatment survival differed (χ2 = 37.4, P < 0.001) among the 5 groups of doves that retained different numbers of pellets, and survival ranged from 0.57 (95% CI: 0.44–0.74) for doves that retained ≤2 lead pellets 2 days posttreatment compared to 0.08 (95% CI: 0.022–0.31) for those doves that retained 13–19 lead pellets on 2 days posttreatment; significant differences existed among the 5 groups. After controlling for dove pretreatment body mass, each additional lead pellet increased the hazard of death by 18.0% (95% CI: 1.132–1.230, P < 0.001) and 25.7% (95% CI: 1.175–1.345, P < 0.001) for males and females, respectively. For each 1-g increase in pretreatment body mass, the hazard of death decreased 2.5% (P = 0.04) for males and 3.8% (P = 0.02) for females. Deceased doves had the highest lead levels in liver (49.20 ± 3.23 ppm) and kidney (258.16 ± 21.85 ppm) tissues, whereas controls showed the lowest levels (liver, 0.08 ± 0.041 ppm; kidney, 0.17 ± 0.10 ppm). For doves dosed with pellets, we observed simultaneous increases in blood lead levels and H:L ratios, whereas packed-cell volume (PCV) values declined. Our results support an acute lead toxicosis hypothesis. Although further research is necessary to investigate the magnitude of lead shot ingestion and toxicosis in mourning doves, we recommend that management agencies initiate development of a long-term strategic plan aimed at implementing a nontoxic shot regulation for mourning dove hunting.

Priority contribution. Role of international conventions in promoting avian conservation through reduced lead toxicosis: progression towards a non-toxic agenda

The transition to the use of non-toxic shot and fishing weights has been slow at the international level despite the Bern Convention and the African Eurasian Migratory Waterbird Agreement (AEWA) having called for a ban on lead shot use by the year 2000. Adopting lead substitutes is also consistent with the habitat goals of the Ramsar Convention and the Biodiversity Convention. In countries where non-toxic shot and sinkers are required by law, published studies show a marked reduction in lead toxicosis and large savings of birds. A renewed commitment from the AEWA, the Bern Convention, and especially the Ramsar Convention is needed to encourage their parties to regulate the use of non-toxic materials. Eleven different non-toxic substitutes for shot now exist, and some of these can also serve as substitutes for lead sinkers. While previous regulatory emphasis has been placed on wetland habitats, any new initiatives could also propose a phasing out of lead shot in upland habitats to reduce the prevalence of secondary lead poisoning of migratory raptors.

Effects of Nontoxic Shot Regulations on Lead Accumulation in Ducks and American Woodcock in Canada

Prior to the first nontoxic shot zones being established in Canada, a nationwide survey of lead (Pb) concentrations in wing bones of hatch year (HY) dabbling and diving ducks determined the incidence of elevated Pb exposure in waterfowl in different parts of the country (Scheuhammer and Dickson 1996). The main objectives of the present study were (1) to compare these previously collected data with the incidence of elevated Pb accumulation in the same species several years after the establishment of a national regulation in 1997 prohibiting the use of Pb shot for waterfowl hunting; and (2) to survey waterfowl hunters to determine reported levels of compliance with the nontoxic shot regulation. Average bone-Pb concentrations in dabbling ducks (mallards [Anas platyrhyncos] and American black ducks [Anas rubripes] combined) decreased significantly between 1989+1990 and 2000 (11 microg/g vs. 4.8 microg/g, respectively [p < 0.01]). Ring-necked ducks (Aythya collaris) showed a similar decrease in mean bone-Pb concentrations, from 28 microg/g to 10 microg/g (p < 0.01). These declines in bone-Pb concentration were consistent with the results of a large anonymous hunter survey, which indicated a high level of reported compliance (>80%) with the nontoxic shot regulation among waterfowl hunters residing in Ontario and British Columbia. Conversely, American woodcock (Scolopax minor), an important upland game species not affected by the nontoxic shot regulation, showed no decrease in mean bone-Pb concentration since the national regulation came into effect (19 microg/g in 1995 vs. 21 microg/g in 2000). A majority (70%) of waterfowl hunters in British Columbia and Ontario who also hunt upland game birds report continued (legal) use of Pb shot for upland game bird hunting.

Acute toxicity of lead, steel, and an iron-tungsten-nickel shot to mallard ducks (Anas platyrhynchos).

Twenty mallards (Anas platyrhynchos) of both sexes were dosed by oral gavage with Heavi-Shot (H-S; Environ-Metal, Inc., Sweet Home, Oregon, USA) pellets, 20 with steel shot, and 10 with lead (Pb) pellets, all of equal size. All pellets were fired from a shotgun into an absorbent material, retrieved, and weighed prior to introduction into the ducks. Birds were fed whole kernel corn and grit and observed for signs of toxicity for 30 days following dosing. Hevi-Shot pellets lost an average of 6.2% of their mass and steel shot pellets lost 57% of their mass in the birds' gizzards. Almost all (90%) of the Pb shot dosed birds died before the end of the study, while no mortality was observed in the steel or H-S dosed groups. Even though total food consumption differed between the H-S and steel shot groups, mean bird weight change was not different. There were no significant morphologic or histopathologic abnormalities of the liver and kidney in the H-S and steel shot groups. Results indicated that mallards dosed orally with eight No. 4 H-S pellets were not adversely affected over a 30-day period, and that H-S provides another environmentally safe nontoxic shot for use in waterfowl hunting.

Ingestion of Lead and Nontoxic Shotgun Pellets by Ducks in the Mississippi Flyway

We examined the extent to which ingested nontoxic (steel and bismuth-tin) shotgun pellets replaced toxic (lead) pellets in ducks harvested in the Mississippi Flyway during the 1996 and 1997 hunting seasons (fifth and sixth yr after nationwide conversion to nontoxic shot). Gizzards were collected from 16,651 ducks and processed for the presence of pellets. Prevalences of ingested pellets were 8.9% for 15,147 mallards (Anas platyrhynchos), 12.7% for 749 ring-necked ducks (Aythya collaris), 4.3% for 579 scaups (Aythya affinis and A. marila), and 9.7% for 176 canvasbacks (Aythya valisineria). For gizzards with ingested pellets, as much as 68% of mallard, 45% of ring-necked duck, 44% of scaup, and 71% of canvasback contained only nontoxic pellets. We estimated that nontoxic shot reduced mortality from lead poisoning in Mississippi Flyway mallards by 64%. Ingestion of ≥2 toxic pellets declined by as much as 78%. To the extent that our findings apply to other species and flyways in North America, an estimated 1.4 million ducks in the 1997 fall continental flight of 90 million were spared from fatal lead poisoning. Only 1.1% of 1,318 gizzards positive for shot-in pellets came from ducks shot with toxic pellets, and only 1 toxic fishing sinker was found in the 16,651 duck gizzards.

Lead Exposure in American Black Ducks after Implementation of Non-Toxic Shot

Lead poisoning from the ingestion of spent shotgun pellets has been recognized as an important disease of North American waterfowl since Bellrose's (1959) research >40 years ago. Nation-wide regulations banning the use of lead shot for waterfowl hunting were established in 1991. We compared the prevalence of lead exposure in American black ducks (Anas rubripes) wintering on 2 areas in Tennessee before (1986-88) and after the ban (1997-99) to assess the effect of the ban on lead shot on this species. Prevalence of elevated blood lead in black ducks declined by 44% from before (11.7% prevalence) to after (6.5% prevalence) the implementation of non-toxic shot. The reduction in lead exposure was pronounced in adult black ducks (from 14.3% to 5.3%). However, prevalence in lead exposure remained similar in juvenile black ducks (from 8.2% to 8.3%). Additional evidence from lead ingestion and lead poisoning mortality events also indicates that lead exposure has declined in waterfowl in the Mississippi flyway. We believe that lead ingestion will continue to decline, despite the persistence of lead shot in some wetlands. The impact of reduced lead exposure on waterfowl populations needs to be assessed.

Elevated lead concentrations in edible portions of game birds harvested with lead shot

Here, we report the results of a study to determine the frequency of elevated Pb concentrations in pectoral muscle tissue of hunter-killed game birds (mostly waterfowl), and to address the cause of occasionally observed high Pb values. Of 827 right pectoral muscle pools (1–12 individuals per pool), 92 had Pb concentrations greater than 0.5 μg/g wet weight, (∼2 μg/g dry weight). The average Pb concentration for these 92 pools was 12±38 μg/g wet weight (∼40±125 μg/g dry wt). When tissue from individuals making up some of these `high Pb' pools were analysed, 40 of 190 individual birds had Pb concentrations >5 μg/g dry weight in their right pectoral muscles. All tissue samples were examined visually prior to analysis, and none contained detectable Pb pellets. The average concentration of Pb in right pectoral muscle tissue of individual birds from high Pb pools with elevated muscle-Pb concentrations was 211±634 μg/g ( n=40) and ranged from 5.5 to 3910 μg/g (dry wt). Large differences in Pb concentrations between right and left pectoral muscle of the same individuals, were often noted. The magnitude of the differences in Pb concentrations between left and right pectoral muscles of the same individual, and also between different samples taken from the same tissue, preclude both analytical error and biologically incorporated Pb as the cause of the elevated Pb concentrations in these animals. Radiography confirmed the presence of numerous small (<1 mm diameter) metallic fragments in pectoral muscle samples from these birds. Embedded fragments of metallic Pb from shot disintegration are a potential source of dietary Pb exposure for predators, and for human consumers of wild game, especially in communities that rely on subsistence hunting and for whom hunter-killed wild game represents a major food source. This risk can be eliminated by the use of non-toxic shot for hunting.

Lead Pellet Ingestion in First Nation Cree of the Western James Bay Region of Northern Ontario, Canada: Implications for a Nontoxic Shot Alternative

Subsistence hunting for Cree of the western James Bay region of northern Ontario, Canada, is a way of life. In this study, it is shown that ∼15% of the radiographic charts examined had evidence of pellets contained in the gastrointestinal system, intraluminally, and/or in the appendix. It is assumed that the consumption of wildgame with lead shot embedded in the tissue was the source of the pellets. Because the presence of lead shot in the human gastrointestinal tract appears to increase the body burden of lead and considerable evidence is available on the occurrence of lead poisoning in waterfowl due to the ingestion of lead pellets,it is suggested that the use of lead shot should be discontinued nationwide in Canada. Although bismuth/tin shot has been growing in appeal because of several recent waterfowl studies demonstrating its nontoxic nature, caution is advised because of the uncertainty about the toxicity of bismuth in humans, especially when consumed as whole pellets or fragments in wildmeats. We maintain that the nontoxic alternative of choice at this time is steel shot.

Preventing lead toxicosis of European waterfowl by regulatory and non-regulatory means

SummaryMany years of waterfowl hunting have added thousands of tonnes of lead shot to European wetlands. Effective and non-toxic substitutes for lead shot have been developed and are commercially available throughout Europe, but few nations (Denmark, Finland, Norway and the Netherlands) have statutory requirements for their use. Governments can induce hunters to use non-toxic shot by regulatory measures and/or non-regulatory steps, but economic incentives to increase the affordability of lead-free shot have never been used by any nation and might be politically inappropriate. Educational programmes to increase the hunting public's understanding of the poisoning problem, and to provide accurate information on the non-toxic shot, are the best long-term way for governments to focus their spending and induce change, whether on a voluntary or regulated basis. Each of the six nations which has moved to end lead poisoning of waterfowl has adopted a regulatory approach, but these nations have acted independently of each other, and yet the use of non-toxic shot should apply to all countries of a flyway.Several European treaty and policy precedents could form the basis of a pan-European regulation requiring the use of non-toxic shot. A proposal to eliminate the use of lead shot in wetlands has been made under the Bonn and Bern Conventions. An European Union-USA proposal to reduce the use of different categories of lead under an Organization of Economic Cooperation and Development Council Act has been made, but has deleted an earlier recommendation that lead shot be included. The substitution of lead shot by nontoxic alternatives is also consistent with the European Council Directive on the Conservation of Wild Birds of 1979. The passing of a European Council regulation, stipulating the minimal acceptable standards for shot used for waterfowl hunting, is seen as the most effective way to remediate this transboundary toxic problem. This type of action by the European Union, while recognizing the Principle of Subsidiarity, would still allow other member states to enact more rigorous legislation pertaining to the use of lead shot within their jurisdiction, as have Denmark and the Netherlands. Although responsibility to enact and enforce a European Council regulation is the prerogative of each member state, a single regulation would promote consistency of action amongst all states.

BLOOD LEAD CONCENTRATIONS OF WATERFOWL FROM UNHUNTED AND HEAVILY HUNTED MARSHES OF NOVA SCOTIA AND PRINCE EDWARD ISLAND, CANADA

Blood lead concentrations of juvenile American black ducks (Anas rubripes) sampled in unhunted sanctuaries of Nova Scotia (NS) and Prince Edward Island (PEI), Canada, usually were < 30 parts per billion (ppb). Based on gizzard content analyses of juvenile American black ducks from hunted areas, eight (24%) of 33 flightless birds contained ingested lead shot. Blood lead concentrations were > or = 100 ppb in seven of eight juveniles with ingested shot; thus we adopted blood lead concentrations 100 ppb as our threshold indicating exposure to non-background lead. The proportion of both American black ducks and ring-necked ducks (Aythya collaris) with elevated blood lead concentrations (> 100 ppb) exceeded 5% in hunted areas sampled in NS and PEI combined. The Canadian Wildlife Service draft policy is to consider replacing lead shot with non-toxic shot for waterfowl and snipe hunting if 5% of American black ducks exceed a blood lead concentration of 200 ppb. American black ducks significantly (P < 0.05) exceeded this threshold but ring-necked ducks did not. The source of lead in hunted areas may have been lead shot; we recommend that it be eliminated and replaced by an acceptable non-toxic shot for waterfowl hunting. Twenty four (96%) of 25 of American black ducks overwintering in Sullivans Pond, Dartmouth, NS, contained elevated (> 100 ppb) blood lead concentrations and 19 (76%) had detrimental concentrations (> 200 ppb). We believe that the source of lead at Sullivans Pond was automobile emissions.

Effects of Ingested Tungsten-Bismuth-Tin Shot on Captive Mallards

Steel shot is required for waterfowl hunting in the United States, but hunter dissatisfaction with steel's perceived ballistic performance has reduced compliance with steel shot laws, contributed to the loss of waterfowl hunters nationwide, and renewed interest in an alternative non-toxic shot with ballistic qualities similar to lead shot. We evaluated the acute toxicity of an alternative shot by orally dosing 20 8-week-old game farm mallards (Arras platyrhyrrchos) with 12-17 pellets (x = 1.03 g) composed of tungsten, bismuth, and tin (TBT). Ducks were monitored for 32 days for evidence of intoxication. Eroded shot evident in radiographs taken 11 days post-dosing indicated acute exposure to the constituent metals, but no dosed or undosed birds died during the trial