Outdoors

Forest Ghosts Check Out

What brought down Montana’s caribou?

Woodland caribou used to roam the forests of northwest Montana. Evidence suggests they once moved as far south as Lolo Pass. The animals were hunted by Montana’s native people, as well as white settlers. That lasted until the 1940s, when Montana ended caribou hunting in order to protect vanishing herds.

The animals were last documented in Montana in 2012, when a small herd was relocated to a spot in the Purcell Mountains of British Columbia just 40 miles north of the border. Five of those caribou wandered south. Three were killed by predators. One was discovered paralyzed from tick bites and was treated and released with the herd back in Canada.

A lone bull managed the return crossing on its own.

One caribou herd in the lower 48 lingered in the Selkirk Mountains of Idaho and Washington. But after recent surveys only counted three remaining animals, the species was declared functionally extinct. There will still be occasional visits from wandering caribou this side of the border, including in Montana, but this is a Canadian species now.

What brought down Montana’s caribou? It was likely the familiar litany of land use changes, encroaching human contact, coupled with the fact that caribou were probably never that numerous in the state to begin with. Montana is on the fringe of the animal’s range, a place that may have been sink habitat anyway.

Source-sink habitat dynamics suggest certain areas — source habitat — grow a surplus of animals which migrate to new areas, expanding the species’ range. Those places they wander to are often habitat sinks, places of less ideal conditions where, over time, more animals may be lost than are produced.

The down-the-drain metaphor is unfortunate in that it leads some to think sink habitat isn’t all that important, and protecting it shouldn’t be a priority. That’s misguided at best, and an excuse for habitat destruction in the wrong hands. Without sinks, source populations will suffer as well. When times are good, surplus animals need new places to occupy. And while the sink may lose more animals than it produces, with a steady migration from source habitat, populations in sinks can be stable and long lasting.

And if natural disaster or disease wipes out a source population, the sink may in turn become the source of its recovery.

The caribou are also struggling north of the border due to logging in the alpine habitat where the animals winter. Woodland caribou have hooves like dinner plates, and these nature-made snowshoes allow them to stay above the snow line. They stride on top of the snow, eating lichen called Old Man’s Beard that grows in the branches of old growth trees.

Logging high-elevation old growth forests reduces habitat for woodland caribou. It also brings roads and human traffic that can further stress animals. It’s not a bad thing that we like to play in the same areas caribou need to survive, but we need to be aware of, and mitigate, the impact of our presence.

Climate change may also be a factor. If winter snowfall declines — the evidence of our most recent winter notwithstanding — predators will follow caribou into the high country.

The woodland caribou’s nickname is “gray ghost” as they are so rarely encountered. The 1950s was the high point for sightings in Montana, but that only makes sense. That was a time of increasing encroachment into caribou habitat by humans armed with chainsaws. The animals the loggers encountered were probably being driven to extinction by the loggers’ very activity.

Today we know a lot more about ecological restoration, and the role multiple-use management can play in that restoration, than we did in the 1950s. Hopefully we can put that insight to use restoring a piece of megafauna sadly absent from the puzzle of Montana’s alpine habitat.

Rob Breeding is the editor of www.mthookandbullet.com, which covers outdoor news in Montana.

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