Photos by Cristobal Briceño of WCS Chile
Guanacos, wild relatives of llamas, have only one natural predator, the puma — or so scientists believed.
“Previously, scientists believed that only pumas hunted guanacos, but the small yet powerful foxes have proved them wrong, as this photo illustrates,” the New York-based Wildlife Conservation Society said in a news release.
Photos of culpeos chasing and biting guanacos were taken by WCS researchers on the Chilean portion of Tierra del Fuego, an island off South America. The researchers, who are studying guanaco population dynamics, also documented defensive herding by guanacos when the foxes are present — another first.
The discovery was made at Karukinka — a 700,000-acre (283,000-hectare) private reserve owned and managed by WCS. Donated to WCS by Goldman Sachs in 2004, Karukinka contains the world’s southernmost old-growth forest as well as extensive peat bogs, unique river systems, and grasslands.
The researchers published their findings in the March issue of the journal Mammalia.
There are no pumas on Tierra del Fuego, according to the research paper in the journal. The big cat, known throughout the Americas also as the mountain lion, was “likely absent from the island for much of the last 10,000 to 12,000 years since the rise in sea level isolated the island from the continent,” the researchers say.
The only native terrestrial predator in Tierra del Fuego is the culpeo, which weighs up to 30 pounds (14 kilograms).
There are no published records of culpeo attacks on guanacos and researchers studying culpeo diets that have encountered guanaco remains have assumed that guanacos were consumed as carrion, the paper said.
“Unconfirmed reports from local people throughout the ranges of both species, however, indicate that culpeos may occasionally prey on guanacos up to one year of age,” the paper added. “Culpeos, similar to most canids, are cursorial predators that instead of stalking their prey rely on pursuing and exhausting it to be able to catch it.”
The Tierra del Fuego population currently numbers approximately 60,000 guanacos, after a sharp decline during the last century due to the expansion of sheep ranching.