A comparison of fragmenting lead-based and lead-free bullets for aerial shooting of wild pigs.

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.

Unleaded hunting: Are copper bullets and lead-based bullets equally effective for killing big game?

Semi-jacketed lead-cored or copper-based homogenous rifle bullets are commonly used for hunting big game. Ever since their introduction in the 1990's, copper-based bullets have not been widely accepted by hunters due to limited supply, higher expense, and the perception that they exhibit inferior killing efficiency and correspondingly higher wounding rates. Here, we present data showing that animal flight distances for roe deer, red deer, brown bear, and moose dispatched with lead- or copper-based hunting bullets did not significantly differ from an animal welfare standardized animal flight distance based on body mass. Lead-cored bullets typical fragment on impact, whereas copper-based bullets retain more mass and expand more than their leaden counterparts. Our data demonstrate that the relative killing efficiency of lead and copper bullets is similar in terms of animal flight distance after fatal shots. Hunters that traditionally use lead bullets should consider switching to copper bullets to enhance human and environmental health.

Defining animal welfare standards in hunting: body mass determines thresholds for incapacitation time and flight distance.

Shooting is an important tool for managing terrestrial wildlife populations worldwide. To date, however, there has been few quantitative methods available enabling assessment of the animal welfare outcomes of rifle hunting. We apply a variety of factors to model flight distance (distance travelled by an animal after bullet impact) and incapacitation from the moment of bullet impact. These factors include body mass, allometric and isometric scaling, comparative physiology, wound ballistics and linear kinematics. This approach provides for the first time a method for quantifying and grading the quality of shooting processes by examining only body mass and flight distance. Our model is a universally applicable tool for measuring animal welfare outcomes of shooting regimes both within and among species. For management agencies the model should be a practical tool for monitoring and evaluating animal welfare outcomes regarding shooting of mammalian populations.

The return of the giants: ecological effects of an increasing elephant population.

Northern Botswana and adjacent areas, have the world's largest population of African elephant (Loxodonta africana). However, a 100 years ago elephants were rare following excessive hunting. Simultaneously, ungulate populations were severely reduced by decease. The ecological effects of the reduction in large herbivores must have been substantial, but are little known. Today, however, ecosystem changes following the increase in elephant numbers cause considerable concern in Botswana. This was the background for the "BONIC" project, investigating the interactions between the increasing elephant population and other ecosystem components and processes. Results confirm that the ecosystem is changing following the increase in elephant and ungulate populations, and, presumably, developing towards a situation resembling that before the reduction of large herbivores. We see no ecological reasons to artificially change elephant numbers. There are, however, economic and social reasons to control elephants, and their range in northern Botswana may have to be artificially restricted.

Brown bear body mass and growth in northern and southern Europe.

We tested six hypotheses to explain expected geographical differences in body masses of 1,771 brown bears (Ursus arctos) from northern and southern Europe (Sweden and Norway compared with Slovenia and Croatia): Bergmann's rule, the fasting endurance hypothesis, and the dietary meat hypothesis, which predicted larger bears in the north; and hypotheses stressing the role of high primary productivity, high population density, low seasonality, and length of the growing season, which predicted larger bears in the south. Although brown bear populations in North America vary greatly in body mass, we found no significant difference in body mass between the two European populations using a new analytical approach incorporating modeled age-standardized body masses in linear models, when correcting for sex and season. The greater variation in North America may be due primarily to the presence of large bears that feed on salmon (Oncorhynchus spp.), which does not occur in Europe. Asymptotic body masses were 115 +/- 9 (SE) kg in spring and 141 +/- 9 kg in autumn for southern females, 248 +/- 25 and 243 +/- 24 kg for southern males, 96 +/- 2 and 158 +/- 4 kg for northern females, and 201 +/- 4 and 273 +/- 6 kg for northern males, respectively. Northern bears gained more body mass before hibernation and lost more during hibernation than southern bears, probably because hibernation was twice as long in the north. Northern bears gained and southern bears lost mass during the spring, perhaps due to the greater availability and use of protein-rich food in spring in the north. As reproductive success in bears is correlated with adult female body mass in interpopulation comparisons, brown bears may have relatively similar reproductive rates throughout Europe, although minimum age at primiparity and litter interval are lower in the south.