Mountain goats stick to steep alpine terrain for good reason: protection from less agile predators, like wolves and even brown bears.
But new research indicates that a key feature of that same habitat – avalanche risk – could threaten the stability of mountain goat populations in Southeast Alaska.
“If you have multiple bad years in a row, that could really be catastrophic,” said ecologist Kevin White, a researcher with the University of Southeast Alaska and University of Victoria.
White co-authored the paper, which was published late last month in the journal Global Change Biology. The study concludes that avalanches can spur major mountain goat population declines – an important finding as climate change disrupts alpine environments around the world.
The research hinges on a dataset that covers hundreds of individual goats over more than four decades. The data also covers multiple study areas that span Skagway, Klukwan, Haines, Baranof Island and beyond.
White helped collect some of that data over the course of 17 years. He spent that time flying above Southeast’s coastal peaks, spotting, darting and collaring goats to study how they live or die.
That data allowed him and fellow researchers to analyze how many goats are killed by avalanches in a given year. On average, they wrote in an earlier study, that figure is around 7% but can be as high as 22%.
That finding raised a new set of questions, such as whether avalanches can result in mountain goat population declines and how long it might take them to recover.
To find answers, the researchers modeled goat survival, reproduction and population growth in different avalanche years.
“The take-home message is that, in the worst-case scenario, it can set a population back more than the mountain goat generation,” White said.
One reason why: goat populations grow really slowly – about 1.5% a year on average. That means they live and die on a really narrow margin.
“For every year that’s at the extreme on the bad end,” White said, “you have to have multiple years of being extreme on the good end to compensate for that.”
The finding could be bad news for the species, which Alaska Native people have long used for subsistence, wool and other purposes. Mountain goats also serve as crucial indicators of how alpine ecosystems are functioning more broadly.
That’s especially the case amid rising global temperatures. Scientists predict that climate change will result in more frequent extreme weather events, including atmospheric rivers. Those events deposit a lot of rain at lower elevations – and snow at higher elevations.
Like in 2020, when a record-breaking atmospheric river dumped more than 90 inches of snow on the mountains above Haines.
“Those types of events can lead to instabilities in the snowpack and can lead to more avalanches,” White said.
More research is needed to better understand the relationship between climate change, avalanches and mountain goat survival. White said that’s particularly true in Southeast, which doesn’t have the same level of avalanche forecasting and monitoring as more populated areas.
It’s important to note that avalanches can have positive effects on wildlife, too, White said.
“When avalanches cascade down the hillside, they’re removing snow,” he said. “Those areas we expect will green up sooner in the spring than areas that haven’t slid.”
That could actually expand the growing season for forage resources – a potential boon to mountain goat populations.
