Feral dogs take a bite out of Andean wildlife

A nature reserve high in the Andes and far from where people live would seem, on its face, to be a great place for native wildlife. But even those remote spots aren’t free of the influence of human civilization. One problem that is just now starting to get some attention: feral dogs.

Like feral cats, free-roaming feral dogs can prey on other animals and compete with native wildlife. They may also spread diseases, such as rabies. But the dogs can be especially troublesome because they form large packs that can take down even large prey.

Despite the dangers of feral dogs, these animals aren’t well studied (especially compared with feral cats). And most research on feral dogs has taken place in and around urban areas. Just how big of a problem they are in wild regions isn’t known. But they’ve been spotted in remote areas, including Cayambe-Coca National Park in the northern Ecuadorian Andes.

Galo Zapata-Ríos and Lyn Branch of the University of Florida in Gainesville wanted to see what effect feral dogs were having on native wildlife in the park. They surveyed and placed camera traps in parts of the park in 2010 and 2011 to assess the abundance and activity of more than a dozen native mammals, including mountain paca, northern pudu and Andean fox. Several of the animals are endemic to the region, and a few, such as the mountain tapir and little red brocket deer, are threatened or endangered. The study appears in the January Biological Conservation.

The team found evidence of 13 species of native mammals in the park, but they weren’t distributed evenly. Four small species were completely absent from areas where feral dogs were common. In dog-free areas, though, two of those species, mountain paca and mountain coati, were relatively abundant while the other two species, long-tailed weasel and northern pudu, showed up on camera traps only a few times. The researchers can’t say for certain that the feral dogs were behind the absences, but they suspect the packs did hunt these small mammals.

Six other species — puma, Andean fox, Andean bear, striped hog-nosed skunk, mountain tapir and little red brocket deer — were also lower in number when feral dogs were around. Three of those species also exhibited changes in timing of activity. In areas without dogs, Andean bears, for instance, were most active early in the morning and late in the day. When dogs were around, the bears became more active at midday. Such changes in timing may help animals to avoid encounters with feral dogs, the researchers note, but these changes can also have adverse affects on metabolism, brain activity or behavior.

Zapata-Ríos and Branch witnessed several instances of feral dogs chasing and killing native mammals, including carnivores. “In all cases, dogs had the numerical advantage,” they note. But the effect of predation on native, and often declining, mammals is not the only worry. The dogs might also be killing ground-nesting birds, which were not included in the study. And they may be spreading diseases such as distemper or rabies, the team warns.

But there is good news: The researchers presented their data to local organizations and Ecuador’s government, and there was recognition that something needed to be done to protect the park’s native wildlife. Instituted measures include vaccination and sterilization programs for domestic dogs living in buffer zones near the park, educational efforts for the local community and efforts to eliminate at least some of the feral dogs.

“Given the precarious state of mammals in the tropical Andes and the potential for dogs to affect a large number of native species,” the team writes, “similar strategies for reducing problems with dogs likely are needed urgently in other areas of the Andes as well as elsewhere feral dogs and wildlife interact.”