Climate Change Is Shrinking Italian Mountain Goats

With temperatures rising, chamois are eating less as they move to higher elevations.

(Photo: Tom Mason)

Oct 24, 2014· 2 MIN READ
Hannah Hoag reports on the environment, global health, science, and science policy for Nature, Discover, Wired, and others.

Wild young mountain goats scrambling through the Italian Alps are shrinking. Fast.

Why? Climate change is likely to blame, according to a new study.

Researchers studying the logbooks of hunters have found that year-old chamois are 25 percent lighter today than they were 30 years ago.

“It’s surprising in terms of how dramatic the change in terms of magnitude and speed,” said Tom Mason, an ecologist at Laval University in Quebec City. The research was published in Frontiers in Zoology.

Chamois are goat-like animals that are hunted for their meat, horns, and leather across the central Italian Alps region every year between mid-September and late December. When a hunter shoots a chamois, he has to report the animal’s body mass and sex. Between 1979 and 2010, hunters shot 10,455 animals in the Adamello, Presanella, and Brenta districts. Over time, the body size of 1.5-year-old male and female chamois dropped, such that goats that once averaged 20 kilograms now weigh 15 kilograms.

“If they’re getting lighter, it could have implications for how much meat is being produced for people in these regions,” said Mason.

Temperatures in the region have risen 3 to 4 degrees Celsius over the past 30 years. Although winters in the region have been slightly warmer, most of the warming has occurred in the spring and the summer. “They are being pushed to high altitudes where it is cooler, but obviously, there is only so high you can go before you run out of mountain,” said Mason.

(Photo: Tom Mason)

At first Mason and his colleagues from Durham University in Durham, England, and the University of Sassari in Sardinia, Italy, thought that decreases in the abundance or quality of food might be having an effect on the body size of the chamois. But satellite data measuring vegetation greenness found that it hadn’t changed much over the time period.

Next the researchers investigated whether warmer temperatures might be changing the animals’ behavior and limiting the amount of food they were eating. Other Alpine animals rest to avoid overheating on warm days. Male ibex, for example, suffer from heat discomfort when temperatures range between 15 to 20 degrees Celsius, so they cut back on the amount of time they spend searching for and eating grass, moss, flowers, and shrubs.

“The higher temperatures may mean that the chamois spend less time foraging and more time resting,” said Mason. The chamois are fleet of foot, but navigating the mountainous landscape burns up a lot of energy. Their smaller body mass might also help them cool off faster.

“More and more of these sorts of trends are popping up,” said David Hik, an ecologist at the University of Alberta, in Edmonton.

Hik and his colleagues have found that ground squirrels have adjusted their foraging behavior as woody shrubs have moved into arctic and alpine environments. Hik added that the satellite images Mason used in the study don’t reveal whether the plants are species the chamois like to eat.

Mason uncovered a second—but slightly less strong—effect. The goats’ populations had been growing, possibly because of hunting restrictions, which may have led to more competition for the top grazing spots.

Warming temperatures seem to be driving changes in body size of other Alpine animals.

In the French Alps, female alpine marmots, which share their peaks with ibex and chamois, have also been getting smaller. A study published last year found that thinning snow cover had stripped away the insulation from marmot burrows, forcing them to use more energy to maintain their body temperature during the winter. Appalachian salamanders and Scottish Soay sheep have also become smaller and lighter owing to climate change.

“The warming is obviously going to continue,” said Hik. “And animals are going to have to figure out how to deal with it.”