Elsevier

Biological Conservation

Volume 201, September 2016, Pages 1-9
Biological Conservation

Predation of wildlife by free-ranging domestic dogs in Polish hunting grounds and potential competition with the grey wolf

https://doi.org/10.1016/j.biocon.2016.06.016Get rights and content

Highlights

  • Analysis of impact of rural free-ranging dogs on wildlife at a national scale

  • Over 138,000 free-ranging dogs were detected annually on Polish Hunting Grounds.

  • Over 33,000 wildlife and 280 livestock were killed by free-ranging dogs annually.

  • Wolves ate similar prey and killed dogs, suggesting intraguild competition.

Abstract

Although the domestic dog (Canis familiaris) is a ubiquitous exotic predator that can detrimentally affect natural environments, studies on their ecological impact are relatively scarce, particularly at a national scale. We exploited data derived from Polish Hunting Association reports to provide a national evaluation of rural free-ranging dogs in Poland. Our results demonstrate that free-ranging dogs are widespread and abundant, frequently killing wildlife and livestock in Poland and likely exerting intraguild competition with native carnivores such as grey wolves (Canis lupus). On average, hunting club records estimate that over 138,000 rural free-ranging dogs occurred annually in hunting grounds. In addition, nearly 3000 free-ranging greyhounds and their mixed breeds occurred annually on hunting grounds, although greyhound hunting has been banned in Poland and they are legally required to be restrained within fencing. On average, over 33,000 wild animals and 280 livestock were killed by free-ranging dogs on Polish hunting grounds annually. The number of both wild animals and livestock killed by dogs were strongly and positively correlated with the numbers of rural free-ranging dogs recorded on hunting grounds, reflective of their predation pressure. Also, the number of wild animals killed by dogs was positively correlated with estimates of population sizes and harvest levels of wildlife, reflective of prey availability. Dog predation, in conjunction with harvest by humans, may cause unsustainable off-take rates of some game species. Grey wolves, documented within 39 of the 49 Hunting Districts, ate similar prey as dogs, including ungulates and livestock, and killed dogs on hunting grounds, suggesting both resource and interference competition between these sympatric canids. This comprehensive analysis provides important information about the ecological impact of free-ranging dogs and recommendations for alternative legislative and management measures to control their impacts.

Introduction

Domestic dogs (Canis familiaris) are among the most popular companion animals and one of the world's most common carnivores (Gompper, 2014b). Globally, dog ownership is widespread, ranging from 37% of US households (AVMA, 2012), 27% of European households (FEDIAF, 2010), 39% of Australian households (AHA, 2014), and up to 86% of households in Chile (Sepulveda et al., 2014, Silva-Rodríguez and Sieving, 2012). The worldwide dog population is estimated to be between 700 and 900 million (Gompper, 2014b, Hughes and Macdonald, 2013). Given their close association with and subsidies from humans, dogs have access to most ecosystems globally (Gompper, 2014b, Hughes and Macdonald, 2013, Young et al., 2011).

A growing body of literature demonstrates that dogs can have significant detrimental effects on natural environments. For example, dogs act as predators of a variety of native fauna, primarily mammals but also birds, reptiles, amphibians, and invertebrates, and also prey on domestic livestock (Hughes and Macdonald, 2013, Ritchie et al., 2014, Vanak and Gompper, 2009, Young et al., 2011). Non-lethal interactions can also disturb wild animals, including disruption of physiology and normal behaviour such as foraging, vigilance, and bedding (Weston and Stankowich, 2014). Dogs carry pathogens transmissible to wildlife and humans, serving as reservoirs and vectors for disease such as rabies and canine distemper virus (Knobel et al., 2014, Macpherson et al., 2013). Intraguild interactions between domestic dogs and native carnivores can be particularly impactful. Dogs act as resource and interference competitors with sympatric carnivores, competing for prey and carrion and excluding, and sometimes killing, predators in their guild (Butler and du Toit, 2002, Vanak et al., 2014, Vanak and Gompper, 2009). Conversely, dogs also serve as prey for other carnivores, exacerbating human-carnivore conflict (Butler et al., 2014, Kojola and Kuittinen, 2002, Young et al., 2011). Additionally, dogs hybridize with native canids, including wolves (Canis lupus. Canis simensis), jackals (e.g., Canis aureus), and coyotes (Canis latrans), resulting in loss of genetic integrity (Leonard et al., 2014).

Recent publications (e.g., Hughes and Macdonald, 2013, Lescureux and Linnell, 2014, Ritchie et al., 2014) stress the paucity of scientific studies on the ecological impact of domestic dogs. Research on the impacts of domestic dogs at a national rather than local scale are notably scarce. Legislation in Poland specific to dogs and wildlife provides an unusual opportunity to conduct such an analysis. The 1995 Hunting Act in Poland stipulates that hunting can be exercised only by members of the Polish Hunting Association (PHA), with Poland divided into hunting grounds managed by hunting clubs within 49 Hunting Districts. Recent data estimate 116,000 hunters in the 2550 PHA hunting clubs (CSO, 2014). Although members of hunting clubs can hunt free of charge, they are obliged to deliver the harvested animals to hunting club headquarters as all game belong to the Polish government. Hunting Districts must prepare annual hunting reports that include data on hunting ground management, annual harvest, and estimated population sizes of game species. In addition, reports include information on free-ranging dogs, both owned and stray, including greyhounds, which are still illegally used for hunting.

Poland contains an estimated 6–8 million dogs (Fiszdon and Boruta, 2012, Tasker, 2007), including between 75,000 and 650,000 strays (Kołłątaj et al., 2011, Tasker, 2007). No study has evaluated the population status, management, and ecological impact of free-ranging dogs in Poland. Here, we exploit data derived from Polish Hunting Association reports to provide the first national evaluation of rural free-ranging (RFR) dogs, including their numbers and their prey recorded by hunting clubs between 2001 and 2011. We hypothesized that dog abundance would positively predict depredation of wildlife and livestock on hunting grounds. We also hypothesized that depredation events would be positively correlated with prey availability, as indexed both by estimated population sizes of wildlife as well as hunter harvest. In addition, we evaluated available data on the geographic distribution of free-ranging grey wolves in Poland between 2006 and 2011 to predict the degree of spatial overlap and hence potential intraguild interactions by dogs and wolves. This comprehensive analysis represents one of the first such studies of dogs and their impacts on a national scale and provides important guidance on alternative legislative and management measures to control their impacts.

Section snippets

Study area

The study was conducted in Poland, a 322,575 km2 country with an estimated 38.5 million people, including 23.3 million urban and 15.3 rural residents (CSO, 2014). Poland contains 4696 hunting grounds encompassing 252,546 km2. Each hunting ground is rented and managed by a hunting club for at least 10 years. Each hunting club contains at minimum 10 hunters. According to the Polish Hunting Act, each hunting club must employ at least one hunting guard who lives in close proximity to the hunting

Rural free-ranging dogs and greyhounds

RFR dogs were recorded in all 49 Hunting Districts, primarily in central and eastern Poland (Fig. 1a). Between 2001 and 2011, the estimated average annual number of RFR dogs (excluding greyhounds) recorded in hunting grounds in Poland was 138,286 (SD: 8859.2; min-max: 126,157 in 2007 – 154,858 in 2001), of which 29.4% (SD: 0.84; min-max: 28.3% in 2006 – 31.1% in 2010) were stray dogs (Table 1). The estimated annual average number of observed free-ranging greyhounds in hunting grounds was 2990

Discussion

Our results demonstrate that free-ranging dogs are widespread and abundant in Poland, frequently killing wildlife and livestock. On average, hunting club records estimate that over 138,000 RFR dogs, nearly 30% of which were unowned strays, occur annually across the 49 Polish Hunting Districts. In addition, estimates suggest that nearly 3000 free-ranging greyhounds and their mixed breeds occurred annually in hunting grounds, although greyhound hunting has been banned and they are legally

Conclusions

Our results indicate the potential scope and impact of free-ranging dogs in Poland. A large number of unconfined dogs have access to natural areas, causing direct mortality of a variety of wildlife species and livestock, and consequently they may compete with the legally-protected grey wolf. In addition, it is conceivable that the additional animals killed by dogs, in conjunction with those harvested by humans, may result in an unsustainable off-take of some game species. This might be

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