Suchergebnisse

Abstract Context Helicopter-based shooting has been widely used to kill deer in Australasia, but the animal welfare outcomes of this technique have not been evaluated. Aim To assess the animal welfare outcomes of helicopter-based shooting of deer in Australia by quantifying the fates of deer seen and shot at, the duration of procedures and the number and location of bullet wounds in deer. Methods Three deer control operations were assessed. These operations targeted: (1) chital deer (Axis axis) in Queensland, (2) fallow deer (Dama dama) in Australian Capital Territory and (3) fallow deer in New South Wales. For each operation, an independent veterinarian conducted ante-mortem (i.e. from the helicopter as shooting occurred) and post-mortem (i.e. from the ground after shooting had ceased) observations. The ante-mortem data were used to estimate the proportion of deer seen that were shot, chase time (CT), time to insensibility (TTI) and total time (TT; CT + TTI). The numbers and locations of bullet wounds were recorded post-mortem. Key results Ante-mortem and post-mortem observations were performed for 114–318 and 60–105 deer, respectively, in the three operations. Shots were fired at 69–76% of deer that were observed. Median CT ranged from 73 to 145 s. Median TTI ranged from 17 to 37 s and median TT ranged from 109 to 162 s. The mean number of bullet wounds per deer ranged from 1.43 to 2.57. Animal welfare outcomes were better in the two fallow deer operations than in the chital deer operation. In both fallow deer operations, most deer were shot multiple times and at least once in the head or thorax. In contrast, chital deer were shot fewer times and less often in the head or thorax, and non-fatal wounding was observed. Conclusions The best animal welfare outcomes were achieved when helicopter-based shooting operations followed a fly-back procedure and mandated that multiple shots were fired into each animal. Implications Animal welfare outcomes for helicopter-based deer shooting in Australia could be improved with a national-level standard operating procedure requiring helicopters to fly back over shot animals and repeatedly shoot animals in the head or thorax.

Context Helicopter-based shooting has been widely used to harvest deer or control overabundant populations in Australasia, but the effectiveness and cost of this method as a deer control tool has seldom been evaluated. Aims We evaluated the effectiveness and costs of helicopter-based shooting of fallow deer (Dama dama) and chital deer (Axis axis) in eastern Australia by quantifying (1) reductions in density, (2) the relationship between numbers killed per hour and deer density (i.e. the functional response), (3) the costs of control and (4) the effort–outcome and cost–outcome relationships. Methods We evaluated the costs and effectiveness of 12 aerial shooting operations aiming to reduce fallow deer (n = 8) or chital deer (n = 4) population densities at nine sites in eastern Australia. Sites were characterised by fragmented woodland, and all but one operation aimed to reduce grazing competition with livestock. We used pre-control population density estimates and operational monitoring data to estimate the costs and outcomes of each operation. We combined data from all operations to estimate the relationship between shooting effort and population reduction, as well as costs associated with different levels of effort. Key results Population reductions for operations ranged from 5% to 75% for fallow deer, and from 48% to 88% for chital deer. The greatest population reductions occurred when effort per unit area was greatest, and the largest reductions in deer density occurred when shooting was conducted in consecutive years. The functional response of hourly kills to deer density was best described by a modified Ivlev model, with the asymptotic kill rate estimated to be 50 deer per hour. There was no support for the existence of a prey refuge, that is, a threshold population density below which no deer could be shot. Helicopter charter was the primary cost of helicopter-based shooting programs, followed by labour; firearm and ammunition costs were relatively minor. Conclusions Helicopter-based shooting can rapidly reduce deer populations over large geographic areas, but the magnitude of the reduction depends on the effort (hours of shooting) per deer per km2. Implications Aerial shooting operations should include a pre-control population survey so that (1) measurable objectives can be established, (2) the likely level of effort and cost required for objectives to be met can be estimated and planned for, and (3) the realised population reduction can be estimated.