Free-ranging domestic dogs: a threat for wild birds? Attacks on penguins in a protected area

Seabird colonies can be affected by the presence of free-ranging dogs in the natural environment. Extreme negative situations can occur when dogs engage in surplus killing, a common behavior exhibited by carnivore predators in which they kill more prey than they can immediately eat. During October and November 2016, at least 400 adults of Magellanic penguins (Spheniscus magellanicus) were killed at Isla Quiroga (Ría Deseado Provincial Nature Reserve, Santa Cruz, Argentina) by attacks of at least four free-ranging domestic dogs, which managed to reach the island by swimming from the continent (<60m) during days with extraordinarily low tides. The cost to this colony of this threatened penguin species, before the enforcement authority managed to catch the dogs (during a crossing), was a reduction of 14% of its breeding population. This is the first record of such magnitude of adult penguins predation by dogs on the Argentine coast. During recent years, the increase in the number of free-ranging domestic dogs in Puerto Deseado (the town adjacent to the Nature Reserve), due to a lack of dog owners’ responsibility and of an effective legislation which controls dogs, could explain a greater presence of free-ranging dogs in this Reserve, which, along with a very poor patrolling and management of the protected area, has caused this serious conflict with the wildlife.