Dogs And Threatened Species: A Global Review

Numerous studies have investigated the ways in which stray and companion cats can negatively impact wildlife through threats such as predation and disease transmission. But, very few studies have investigated how domestic dogs may pose similar threats. This paper, published in Biological Conservation, builds on the few studies that have examined the impact of dogs on wildlife. It assesses the global prevalence of different types of dog impact. And it identifies hotspots containing high numbers of impacted species.

The authors primarily used information from the IUCN Red List of Threatened Species. They downloaded data from the list for all species in the taxonomic classes of amphibians, birds, mammals, and reptiles. They filtered the data to identify the species for which dogs were listed as “major threats.” They also cross-checked their list with previous reviews and added several more species to the list. This gave a total of 199 affected species. For each species, they recorded information on taxonomic classification, Red List status, region, and category of impact. The results are as follows:

• Out of the 199 affected species, 11 are already extinct, 30 are classed as Critically Endangered, 71 Endangered, and 87 Vulnerable. The authors note that their total number of affected species is nine times higher than that found by a previous literature assessment. It is also 30–50% more than that identified by a previous database review. This suggests that many people (researchers and the public alike) may grossly underestimate the impacts of domestic dogs on wildlife.
• The total number of affected species includes 96 mammalian, 78 avian, 22 reptilian, and three amphibian species. The authors note that previous studies identified large numbers of mammals but not large numbers of birds.
• Predation is the most frequently reported impact. This is followed by disturbance, disease transmission, competition, and hybridization.
• The regions with the highest number of impacted species are South-East Asia (30 species), Central America and the Caribbean (29), South America (28), Asia (25 species), Polynesia (24), and Australia (21). The authors suggest that a greater number of affected species in a particular region may be related to higher dog-to-human population ratios, higher native species richness, and/or a region’s insular nature.

In their discussion, the authors highlight several key areas for further research. This includes the impact of dogs on several species of ground-dwelling birds, the impact of dogs on other species from non-consumptive effects (i.e., fear of predation as opposed to predation itself), and the strength of the impact of dogs compared to other threats like habitat loss or hunting. They also call for an increased understanding of the anthropogenic factors that may exacerbate dog impacts on wildlife. These include increased urbanization and road building, particularly in identified hotspots.

Finally, the authors note that any efforts to better understand and manage dog impacts on wildlife will “require a multidisciplinary approach involving ecological, cultural, social and economic perspectives, on account of the complex relationships that exist between humans and dogs.” They offer possible solutions such as integrating human health and animal welfare objectives into dog management, promoting responsible dog ownership, and removing stray dogs from certain areas.

For advocates, this paper may draw attention to an area of wildlife conservation that has traditionally received little attention. The impact of domestic dogs on wildlife is significantly less than that of domestic cats, particularly for birds. But, the findings suggest that dogs still pose a threat to a large number of species and in specific areas of the world. Advocates who focus on companion animal welfare in such locations may consider taking wildlife into account when formulating policies focused on dog protection and management.