Prevalence of embedded shotgun pellets in protected and in legally hunted medium-sized carnivores in Denmark
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- Elmeros, M., Holm, T.E., Haugaard, L. et al. Eur J Wildl Res (2012) 58: 715. doi:10.1007/s10344-012-0621-7
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Illegal killings of protected species may significantly affect their population status or lower recovery rates after protection. Poaching is difficult to monitor directly, hence indirect methods are required to document poaching incidences and levels. The use of shotguns inevitably results in wounding some animals that are not killed. Inefficient hunting methods may result in high annual infliction rates in game species. To reduce wounding of game species, an action plan was implemented in Denmark. Using X-ray analysis, we monitor trends in prevalence of embedded shotgun pellets in the legally hunted red fox (Vulpes vulpes) after the implementation of the action plan, and assess poaching levels of two protected species, the otter (Lutra lutra) and the badger (Meles meles) in Denmark. Overall, 13.8% of the red foxes and 6.9% of the otters carried embedded shotgun pellets, while none were recorded in badgers. The prevalence of embedded shotgun pellets in red foxes declined from 24.9% to 8.5% from the late 1990s to the late 2000s, while no change was recorded in otters. Prevalence of embedded shotgun pellets was similar in otters and red foxes collected in the late 2000s. The decline in wounded red foxes suggests that the hunting methods have changed after the action plan was implemented in Denmark. The high proportion of otters carrying embedded shotgun pellets shows that there is a significant poaching of this protected species in Denmark, possibly by hunters and fish farmers that cannot distinguish between otter and non-native American mink (Neovison vison).
KeywordsEmbedded shotgun pelletsHuntingPoachingWoundingX-ray analysis
Population status of long-lived species with low annual reproductive output and low population densities is sensitive to variations in adult mortality (Saether and Bakke 2000; Schorcht et al. 2009). These features characterize population dynamics for large and many medium-sized carnivore mammals (Gittleman et al. 2001). Over-harvest and illegal killing of carnivores may cause population declines or slower recovery rates after they have been protected (Woodroffe and Ginsberg 1998; Liberg et al. 2011). Illegal killings of protected carnivores are often reported but indirect methods are required to assess the levels as poaching incidents are difficult to assess directly (e.g. Thali et al. 2007; Gavin et al. 2010).
X-ray analysis of prevalence of embedded shotgun pellets is a feasible method to study poaching. The use of shotguns inevitably causes non-lethal wounding of some animals that are inflicted but not killed by pellets. X-ray analysis has been used to assess crippling of game birds (e.g. Norman 1976; Jonsson et al. 1985; Noer et al. 1998, 2001; Falk et al. 2006), and to document and asses poaching level on protected birds (e.g. Andersen-Harild et al. 2002; Newth et al. 2011). However, the method has rarely been used for systematic studies of poaching levels of protected carnivores and crippling rates of mammalian species (Madsen et al. 1994; Noer et al. 2001).
The otter (Lutra lutra) is protected in most parts of Europe (Foster-Turley et al. 1990; European Commission 1992). Poaching of otters are regularly recorded (e.g. Gutleb et al. 1995; Hauer et al. 2002a; Ó Néill et al. 2008) and may constitute the major known anthropogenic cause of deaths in some countries (Georgiev 2007). Madsen et al. (1994) found embedded shotgun pellets in 5% of otters collected in the early 1990s. Pellets were recorded by X-ray analysis or recovered during preparation of skins at museums.
In Denmark, an action plan to reduce wounding of game species was implemented in 1997 following studies that showed high infliction rates of shotgun pellets in waterfowls, e.g. for pink-footed geese (Anser brachyrhynchus) one bird was wounded but survived for each bird that was killed and retrieved (Noer et al. 1998). Although population status of the examined species was good and hunting pressures were assessed as sustainable, the high infliction rates were regarded as ethically unacceptable by the authorities and hunting and non-hunting organizations (Noer et al. 1998). The action plan aimed at identifying factors contributing to high infliction rates (e.g. hunting method, time, shooting range, shell quality and pellet size) and to disseminate the results to hunters to improve hunting efficiency and lower the risk of wounding game. Restrictions in hunting opportunities and protection of species were proposed as ultimate measure to reduce infliction rates if improvements were not achieved on a voluntary basis by the hunters. The action plan was endorsed before the 1997–1998 hunting season. A monitoring programme for selected game species was set up to investigate the effects of the action plan. In red foxes (Vulpes vulpes) collected after the hunting season in 1998–1999, 24.9% carried embedded shotgun pellets (Noer et al. 2001).
In the present study, we investigate prevalence and temporal trends of embedded shotgun pellets in hunted red fox during the period with increased focus among nature authorities and hunters on the risk of wounding of game species in Denmark. We expect declining prevalence of embedded shotgun pellets in red fox as actions to reduce infliction rates are disseminated to the hunting communities. Furthermore, we analyse otter and badger (Meles meles) carcasses to assess poaching levels of two protected medium-sized carnivores, and to compare prevalence of embedded shotgun pellets in the red fox and protected species. Lower prevalence of embedded shotgun pellets is expected in the protected species than in the game species, and that the prevalence in the protected species is expected to correlate with years since protection.
Material and methods
In Denmark, the otter was protected in 1967 but the population continued to decline during the 1970s and 1980s (Madsen and Søgaard 2001). Since the 1990s, the otter population has recovered due to improved habitat management, lowered pollution levels and reduced rates of incidental captures and killings by construction of fauna passages at road bridges and obligatory use of stop grids in fish fykes in all freshwaters and most marine waters where the species occur (Elmeros et al. 2006). The badger was protected in 1994 following declining annual hunting bag records (Madsen et al. 2007). Present population developments and status of the badger are not known. The red fox has an open hunting season from 1 September to 31 January. It is also legal to cull red foxes near buildings and pens with domestic and game birds throughout the year. The annual bag record for red fox is approximately 40,000 (Danish Game Bag Record: www.vildtudbytte.dk).
Otter and badger carcasses were collected via the public, taxidermists, museums and authorities. Otter carcasses have been collected since 1979. Badgers were only collected in 1995–1998. Seventy percent of the otters and 96% of the badgers were road kills. Otters were aged as subadults or adults based on skeletal characteristics and sexual maturity assessed from the size and morphology of the reproductive organs (Elmeros and Madsen 1999). Excluding juveniles, subadults and adults comprised 46% and 54% of the collected otters. Two random samples of subadult and adult otters collected in 1993–1998 (n = 78) and 2007–mid-2011 (n = 66) were examined for embedded shotgun pellets. The 1993–1998 otter sample includes the 52 X-rayed otters reported by Madsen et al. (1994). A total of 73 badgers were examined. One badger euthanized with a shotgun was excluded from the analyses.
Red foxes were sampled in rural districts to monitor the effects of the action plan to reduce wounding of game species. A total of 1,749 red foxes from 1999 to 2010 were examined. Initially, red foxes were sampled in February after the hunting season (September–January). Since the 2007–2008 hunting season, red foxes were also sampled during the hunting season. The red foxes were shot with rifle or shotgun, the latter using large pellets (size #BB, diameter 4.6 mm). These large pellets are not permitted for hunting in Denmark, and are easily discernible in X-rays from pellets inflicted during normal hunts. A small number of road-killed individuals were included in the study. The monitoring programme of game species was focused on describing annual changes in prevalence of embedded pellets in red fox assuming that the age distribution in the populations and the sampled individuals was stable during the study period. Only red foxes sampled in 2004 were aged as subadults (48%) or adults (52%) from skeletal characteristics (Harris 1978). The numbers of pellets were only recorded in individual foxes from 2004 and onwards. Prior to 2006, red foxes were collected in all regions of Denmark, but since 2006 red foxes were only sampled in southern and central Jutland.
All carcasses were examined for embedded shotgun pellets with standard veterinary X-ray units. Numbers and sizes of embedded pellets were assessed from the X-ray images. Chi-square tests (with Yates correction) were applied to test differences in prevalence of embedded pellets between species and periods. Temporal changes in foxes were tested by regression analysis. The frequency distribution of numbers of embedded pellets in wounded individuals was compared between species with Chi-square test (with Yates correction).
Sampling sizes and periods for medium-sized carnivores examined for embedded shotgun pellets. Otters and badgers were collected during the whole year. Red foxes were sampled in February from 1999 to 2007. Since the autumn of 2007 red foxes were also collected during the hunting season
% with pellets
Sep. 2007–Feb. 2008
Sep. 2008–Feb. 2009
Sep. 2009–Feb. 2010
In otters, there was no change in prevalence of embedded shotgun pellets in animals collected in the 1990s and late 2000s (χ2 = 0.003, df = 1, NS). Otters that carried pellets were collected throughout the species distribution area. Both large and small sized pellets (diameter, 2.5–4 mm) were found in the otters. Mean number of pellets recorded in wounded otters was 6.1 ± 2.1 SE (n = 10). One otter carried 22 large pellets embedded in the tail and rump suggesting that it had been shot at close range.
The prevalence of embedded shotgun pellets in red foxes declined from 24.9% in 1999 to 8.5% in 2010 (r2 = 0.617, t = −3.59, df = 1, P < 0.001). There were no regional differences in prevalence of embedded pellets in red foxes (χ2 = 0.04, df = 1, NS) and in decline rates between 2001 and 2005 (t = 1.46, df = 2, NS), thus we assume that the samples collected in Jutland in 2005–2010 represent the temporal trends in the whole country. Prevalence of embedded shotgun pellets in subadult individuals (9.9%, n = 162) was not lower than in adult individual (13.8%, n = 174; χ2 = 0.67, df = 1, NS). Mean number of embedded pellets in the wounded red foxes was 6.3 ± 3.6 SE (n = 123). The highest number recorded was 69 pellets. Most red foxes that carried more than ten pellets had been shot with small sized pellets (diameter, 2.5–3 mm).
The prevalence of embedded shotgun pellets in otters from the 1990s was lower than in red foxes collected in 1999 (χ2 = 10.7, df = 1, P < 0.005). Following the decline in prevalence of embedded shotgun pellets in red foxes, there was no difference in prevalence of embedded shotgun pellets in otters and red foxes sampled in 2007–2010 (χ2 = 0.11, df = 1, NS).
The declining prevalence of embedded shotgun pellets in red foxes suggests that hunters’ hunting methods and perception of this species have changed during the study period. Unfortunately, no information on the prevalence of embedded shotgun pellets in foxes before the enactment of the action plan to reduce wounding of game species is available, but similar declines in infliction rates have been recorded in game birds after the action plan was endorsed and effected (Noer et al. 2006, 2007). The initial main action of the plan was to comply with maximum shooting ranges, e.g. 25 m for red fox hunting with shotgun as recommended by the authorities, hunting and other nature organizations (Noer et al. 1998). The findings of red foxes carrying many smaller pellets recommended for smaller game birds only. This calls for a higher focus on the use of the adequately sized ammunition for fox hunting or a further reduction in shooting range to reduce infliction rates more.
No embedded shotgun pellets were recorded in badgers collected only a few years after the species became protected showing that hunters comply with regulations on this species. Contrarily, the high prevalence of embedded shotgun pellets in otters shows that there is a high level of poaching of this protected species in Denmark. The poaching may include both intentional and unintentional hunting and culling of otters. Assuming that intentional poaching of otters is low, the high prevalence of embedded shotgun pellets in otters shows that a substantial number of hunters and fish farmers cannot differentiate between otter and other species, e.g. American mink (Neovison vison). Escapees from pelt farms continue to supplement for the feral population (Hammershøj et al. 2005), and hunters are encouraged by the authorities to hunt and cull American mink. Misidentification of pine martens (Martes martes) as stone martens (Martes foina) also results in poaching of the protected pine marten (unpublished data). Similar misidentifications of badgers as a game or an introduced species seem less likely, but the risk may increase as a feral population of raccoon dog (Nyctereutes procyonoides) has recently established itself in Denmark (Skov- og Naturstyrelsen 2010).
Poaching of otters on fish farms is widespread (Foster-Turley et al. 1990; Georgiev 2007). It has previously been assumed that poaching of otters on fish farms in Denmark was low, as fish farmers have assessed their losses due to otter as minor relative to losses caused by other wildlife species (Bruun-Schmidt et al. 2000). Furthermore, the authorities offer guidance to fish farmers on mitigating measures to avoid disturbance and predation by otters (Madsen and Søgaard 2001). However, many fish farmers and aquaculture consultants are unaware of the recommendation and assistance offered by the authorities (Villy Larsen, personal communication).
Similar prevalence of embedded shotgun pellets was recorded in the hunted red fox and the protected otter. The prevalence of wounded animals increases with age (Noer et al. 2007; Madsen 2010; Newth et al. 2011). As annual mortality rate is higher for red fox than for otters (Grue and Jensen 1979; Heydon and Reynolds 2000; Hauer et al. 2002b), a higher proportion of otters would be expected to carry embedded pellets if annual infliction rates were similar. Information on survival rates of red fox and otter in Denmark and the prevalence of embedded pellets in different age classes is needed to estimate annual infliction rates and the potential differences in hunting or poaching pressure of the two species.
The X-ray analyses show that there is a significant poaching level of otters regardless the species’ legal status. This calls for better training and knowledge among hunters and fish farmers on species identification, and better information on non-lethal preventive or mitigating measures on fish farms. Otters have relatively low adult mortality rates and low fecundity (Hauer et al. 2002b; Kruuk 2006). Consequently, adult survival is an important determinant for the population dynamics and status. Member states of the European Union must monitor the incidental killings of otters to ensure that these killings do not reduce the conservation status of the species (European Commission 1992). Systematic collection and X-ray analysis of incidentally killed individuals, e.g. road kills offer a simple method to monitor overall population development and trends in poaching of otters and other medium-sized mammals with shotguns.
We thank the game consultants in the Danish Nature Agency, the Natural History Museum, Aarhus, the Natural History Museum of Denmark, Copenhagen and the private taxidermists for collecting otter and badger carcasses and the hunters who contributed with red foxes. We are grateful to Henning Noer and Poul Hartmann for initiating the monitoring on game species. Trine LW Jensen is thanked for access to previously unpublished data. Henning Noer and two anonymous references provided valuable comments on the manuscript.