The Impact of Pb from Ammunition on the Vegetation of a Bird Shooting Range

Hunting with lead ammunition represents a source of heavy metal pollution to the environment that can be potentially high at the local scale. Intensive hunting of small game species can concentrate high levels of ammunition discharging in small areas. This type of hunting is a relevant economic resource for private landowners in some regions of Spain, and current legislation allows the use of lead ammunition in these scenarios. It becomes, therefore, highly relevant to study whether this activity may pose concerns to the conservation of the environment in the areas where it takes place. Using a red-legged partridge (Alectoris rufa) shooting range as a study area, we examined the effect of intensive hunting on this species on the vegetation present. We found significantly higher lead levels in the sprouts of plants of shooting areas related to control sites of the same property where partridge shooting does not occur. We found differences in the presence of lead between sprouts of different plant species. In addition, old sprouts of existing vegetation in shooting areas also showed higher lead levels than newly emerged sprouts of the same plants. These results demonstrate the impact of lead ammunition on vegetation in terms of persistence over time and differences between species. Further analyses using chemical and ecotoxicological data are necessary to evaluate the extent of environmental pollution risks. Our results provide new support in favor of the use of alternative ammunition, with particular emphasis on scenarios where hunting activity is intensive.

Bioaccessibility of antimony and other trace elements from lead shot pellets in a simulated avian gizzard environment

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.

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.

Reducing Lead on the Landscape: Anticipating Hunter Behavior in Absence of a Free Nonlead Ammunition Program

Lead is a neurotoxin that has been documented to affect many forms of wildlife, and has been identified as a limiting factor in a population of California Condors in Northern Arizona. The Arizona Game and Fish Department provides vouchers for free nonlead ammunition to hunters selected to hunt within the distribution of California Condors, with the intention of having fewer lead-laden offal piles available to California Condors. Although wildlife agencies may reasonably assume voucher programs motivate hunters into choosing nonlead ammunition, the lead reduction efforts attributable to the voucher program has not been empirically quantified. Our intention was to compare a control group of hunters to a treatment group of hunters within California Condor occupied areas. Both groups received educational materials regarding the deleterious effects of lead, but the treatment group also received a voucher for a free initial box of ammunition. About half of the control group used nonlead ammunition, compared to about three-fourths of the treatment group. Prominent barriers to adoption of nonlead ammunition included a general difficulty of obtaining it, obtaining it in the desired caliber, and its costliness. Frequently mentioned motivations for using nonlead was the exhortation to use it by the Department, and the desire to aid California Condor recovery by hunters. The disparate compliance rates found herein confirm and quantify the success of nonlead ammunition voucher programs, but underscore the importance of working to increase the supply of nonlead ammunition with the end of facilitating its procurement and reducing its cost.