Over 130 species of wildlife are known to have died from ingesting lead from ammunition. Upland game animals such as turkey, pheasant, quail, and mourning doves ingest lead shot at they same time they are picking up seeds or grit. Mourning doves are usually hunted over food plots. This practice puts lead shot into their feeding areas. Research shows that when lead shot is used, as many doves die from ingesting lead shot as are harvested. In Iowa, the annual dove harvest is estimated to be at 300,000 birds. Nationally, 17 million doves are harvested. Poisoning this many doves is wasting a valuable resource. USFWS data show declines in dove call count surveys in all three dove management units over the last 45 years.
In 1991, lead shot was banned nationwide for hunting waterfowl (ducks, geese, swans, coots, etc.). Since then, the number of waterfowl hunters (measured by duck stamp sales) has increased by 30%. Waterfowl ingest lead shot when searching for seeds or grit in shallow water areas. Research analyzing the reduction in the number of ducks with lead shot in their crops (digestive tracts) since the ban, shows that millions of ducks have been saved from dying of lead poisoning. This national ban on lead shot for waterfowl is cost effective conservation. It only makes economical sense to get as much production as possible from valuable wildlife habitat areas by not poisoning the very animals for which the habitat was purchased, developed, and maintained.
Wildlife rehabilitators across the country have been documenting an alarming number (over 50% of all eagles admitted) of bald eagles dying from lead poisoning or lead exposure. Isotopic and x-ray research shows the source of this ingested lead to be from ammunition. Lead bullets, slugs, and shot fragment on impact leaving lead fragments in wounded animals and field butchering remains, which are food sources for scavenging eagles and other wildlife. Bald eagles, our national symbol, were on the endangered species list for over 30 years and are now a species of special concern and greatest conservation need in Iowa. Eagle populations are at 10% of historic levels in the lower 48 states.
Handouts available on-line:
Much work in amassing research and reports on lead and non-toxic ammunition has been done by researchers with the Minnesota Department of Natural Resources. In 2006, the department established a citizen advisory committee to provide input on restrictions for lead shot for upland game hunting.
Reports and research involving ammunition show the effectiveness of copper bullets and how lead fragments impact avian scavengers and the benefits to switching to non-toxic ammunition:
Impacts of lead ammunition on wildlife, the environment, and human health—A literature review and implications for Minnesota. Tranel, M.A., AND R.O. Kimmel. 2009. In R. T. Watson, M. Fuller, M. Pokras, and W. G. Hunt (Eds.). Ingestion of Lead from Spent Ammunition: Implications for Wildlife and Humans. The Peregrine Fund, Boise, Idaho, USA. DOI 10.4080/ilsa.2009.0307
- This literature review includes more than 500 citations on lead and non-toxic ammunition related issues worldwide and summarizes the studies regarding ingestion of lead shot, bullets, and fragments by wildlife species and the impacts of lead poisoning on wildlife, the environment, and humans. On pages 3-6 of the document is Table 1 shows species impacted by lead with references.
Many researchers have looked at the impacts of lead on specific species of wildlife.
How Good are Copper Bullets, Really? Bartha, C. and Lehman, P. 2010. Wisconsin Department of Natural Resources
- This investigation evaluates accuracy and performance of non-lead centerfire rifle bullets in sporting and suppressed rifles. A secondary component to this investigation developed an easy, hands-on way for hunters to evaluate non-lead hunting ammunition performance and to compare it with centerfire lead ammunition.
Impact of the California Lead Ammunition Ban on Reducing Lead Exposure in Golden Eagles and Turkey Vultures. Kelly TR, Bloom PH, Torres SG, Hernandez YZ, Poppenga Rh, et al. (2011) PloS ONE 6(4): e17656. doi.10.1371/journal.pone.0017656
- A ban on the use of lead ammunition for most hunting activities in the range of the condor in California was implemented in 2008. Monitoring of lead exposure in predatory and scavenging birds is essential for assessing the effectiveness of the... ban.... In this study...they compared blood lead concentrations in two sentinel species, the golden eagle and turkey vulture, before the ammunition ban and one year following implementation of the ban. Lead exposure in both golden eagles and turkey vultures declined significantly post-ban.
Bullet Fragments in Deer Remains: Implications for Lead Exposure in Avian Scavengers. Hunt et al. Wildlife Society Bulletin 34(1):167-170; 2006.
- Deer offal piles are present and available to scavengers in autumn, and the degree of exposure depends upon incidence, abundance, and distribution of fragments per offal pile and carcass lost to wounding. In radiographs of selected portions of the remains of 38 deer supplied by cooperating licensed hunters in 2002-2004, we found metal fragments broadly distributed along wound channels. Ninety-four percent of samples of deer killed with lead-based bullets contained fragments and 90% of 20 offal piles showed fragments. In contrast, we counted a total of only 6 fragments in 4 whole deer killed with copper expanding bullets.
- Craighead Beringia South is a prominent wildlife research and education institute dedicated to putting science to work for wildlife. Visit their lead and wildlife information page for links to general info about lead, state health warnings, ammunition performance, and research reports.
- The Minnesota Department of Natural Resources conducted the first-of-its-kind lead fragmentation study in 2008 to simulate how different types of bullets commonly used for deer hunting might fragment. Check out the department's website - it has a presentation you can watch that outlines the study's findings. You can also download a short or full report of the study.
After full implementation of the non-toxic ban for waterfowl hunting in the U.S., research was conducted to evaluate prevalence of lead shot in waterfowl.
- Lead Exposure in Bald Eagles from Big Game Hunting, the Continental Implications and Successful Mitigation Efforts. Bedrosian B, Craighead D, Crandall R (2012) PLoS ONE 7(12): e51978. doi:10.1371/journal.pone.0051978.
- Studies suggest hunter discarded gut piles of big game animals are a source of lead available to scavengers. This study investigated the incidence of lead exposure in bald eagles in the Jackson Hole Valley (Wyoming) during the big game hunting season, the invlux of eagles into the study are during the hunt, the geographic origins of eagles exposed to lead, and the efficacy of suing non-lead rifle ammunition to reduce lead in eagles.
- Lead from spent ammunition: a source of exposure and poisoning in bald eagles. L Cruz-Martinez, P Redig, and J Deen, Human–Wildlife Interactions 6(1):94–104, Spring 2012
- Research abstract: Ongoing occurrence of elevated levels of lead in bald eagles (Haliaeetus leucocephalus) following the ban on lead shot for waterfowl hunting led us to hypothesize that spent lead from ammunition, which is present in fi eld residues of white-tailed deer (Odocoileus virginianus), represented a source of lead exposure in eagles. We conducted a case-control study using data from 1,277 bald eagles admitted for rehabilitation [to The Raptor Center] from January 1996 through December 2009. We found 334 bald eagles with elevated lead levels out of 1,277 bald eagles we examined. We detected significantly increased odds for elevated lead levels based on season (late fall and early winter), deer hunting rifle zone, and age (adult birds). These combined results supported our hypothesis that eagles are acquiring lead from hunter-shot deer.
- Lead Poisoning of Bald and Golden Eagles in the US Inland Pacific Northwest Region -- An 18-year Retrospective Study: 1991-2008. Erik Stauber, DVM, PhD, Nickol Finch, DVM, Patricia A. Talcott MS, DVM, PhD, Dipl ABVT, and John M. Gay, DVM, Phd, Dipl ACVPM doi: 10.1647/2009-006.01
- To determine risk factors and seasonal trends of lead poisoning in bald and golden eagles, blood lead levels were evaluated in eagles admitted from the inland Pacific Northwest region to the Raptor Rehabilitation Program at Washington State University from 1992 to 2008. A total of 67 bald and 63 golden eagles were admitted during this time.In these birds, 48% (22/46) of bald eagles and 62% (31/50) of golden eagles tested had blood lead levels considered toxic by current standards. Of these birds with toxic lead levels, 91% (20/22) and 58% (18/31) respectively, were admitted after the end of the general deer and elk hunting seasons in December.
Bald eagle lead poisoning in winter. Neumann, K. In R. T. Watson, M. Fuller, M. Pokras, and W. G. Hunt (Eds.). Ingestion of Lead from Spent Ammunition: Implications for Wildlife and Humans. The Peregrine Fund, Boise, Idaho, USA. DOI 10.4080/ilsa.2009.0119
- Wildlife rehabilitators across the state of Iowa began gathering lead poisoning information on bald eagles beginning in January 2004. Blood, liver, or bone samples were analyzed for lead levels from 62 of the 82 eagles in the database at that time. Thirty-nine of the 62 showed lead levels in their blood or liver indicating lethal poisoning without chelation treatment. Seven eagle showed lead exposure levels. Over 50% of the eagles being admitted to Iowa wildlife rehabilitators have ingested lead. Behavioral observations, time-of-year data analysis, and x-ray information point to lead shrapnel left in slug-shot white-tailed deer carcasses to be a source of this ingested lead.
Ingested shot and tissue lead concentrations in mourning doves. Franson, J.C., S.P. Hanson, and J.H. Schulz. 2009. In R. T. Watson, M. Fuller, M. Pokras, and W. G. Hunt (Eds.). Ingestion of Lead from Spent Ammunition: Implications for Wildlife and Humans. The Peregrine Fund, Boise, Idaho, USA. DOI 10.4080/ilsa.2009.0202
- Poisoning from ingested lead shot is of particular concern in mourning doves, which are often hunted on managed shooting fields where lead shot densities can be high, potentially increasing the risk of lead exposure. Previous studies of lead exposure in mourning doves have been local in scope and sample sizes have varied widely among areas. We provide an evaluation of lead exposure in 4,884 hunter-harvested mourning doves from Arizona, Georgia, Missouri, Oklahoma, Pennsylvania, South Carolina, and Texas.
- More species-specific research is included int eh 2008 Peregrine Fund conference on Ingestion of Lead from Spent Ammunition: Implications for Wildlife and Humans.
- Abstract: 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 year 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.
- Small game hunter attitudes toward nontoxic shot, and crippling rates
with nontoxic shot. Schulz, J.H., R.A. Reitz, S.L. Sheriff, J.J.
Millspaugh, and P.I. Padding. Extended abstract In R. T. Watson, M. Fuller, M. Pokras, and W. G. Hunt (Eds.).
Ingestion of Lead from Spent Ammunition: Implications for Wildlife and
Humans. The Peregrine Fund, Boise, Idaho, USA. DOI 10.4080/ilsa.2009.0306
- This study evaluated reported crippling rates in the U.S. prior to, during, and after implementation of nontoxic shot regulations for waterfowl hunting. This evaluation was extended to make inferences about mourning dove crippling rates if nontoxic shot regulations were enacted. ...we believe the decline that followed full implementation of the nontoxic shot regulation is of ultimate importance when inferring the impacts of lead shot restrictions for mourning doves.