Weather and Wildlife: It’s all about microclimates

Before hopping on a plane and flying to the coast of North Carolina for the holidays and beginning the journey of dragging an old Land Rover back up to Alaska (by way of Yellowstone), I found myself photographing Dall Sheep in the Chugach Mountains. This winter has proven to break records when it comes to snowfall in the Anchorage area – which is a bit ironic given how that the rest of the Northern Hemisphere is in a deep snow drought, the likes of which hasn’t been seen in thirty years. In south central Alaska, however, some thirty inches of snow had already fallen by mid-November. As the snow began to accumulate, I found my gear evolving from boots to mild crampons (spikes for your boots) to snowshoes and poles. And predictably, the more snow, the more sheep, the better the photography.

But mountain sheep are one of the few species for whom more snow, extraordinary amounts of snow, record breaking levels of snow, translates to better wildlife photography, however. For most, there are well defined limits to this.

Take great gray owls and red foxes as an example. Both species thrive in winter and snow – but only to a point.

When the snowpack on the ground reaches around 9 inches in depth, the subnivean zone is created between the ground and the snow. The subnivean zone is where little animals like red-backed and meadow voles spend the winter scurrying about, warmed by the heat of the earth and insulated from the temperature extremes above by the depth of the snow. Northern red foxes and great gray owls are specialists at hunting these rodents in the subnivean zone, which I have written about many times before. But there is a limit to their ability to do so. Once the snowpack is greater than two feet deep, theses owls and foxes are shut out. Great grays are forced to move on in search of better conditions and foxes shift their efforts from meadows and muskegs to microclimates in forested areas where snow is shallower.

The winter of 2023 across the Northern Rockies saw record breaking snow totals and cold with two back-to-back blizzards of historic proportions to kick off the season. Temperatures dropped to minus 50 degrees Fahrenheit with wind chills that plummeted to below minus 80 in locations during the blizzards. I was in Minnesota at the time photographing owls when the first of these storms hit. Temperatures were so low that both of my truck’s batteries quite literally froze and had to be replaced.

Arriving in Jackson Hole, Wyoming, just after Christmas, I found the valley covered in several feet of snow that had completely buried the bitterbrush across the valley. Moose in Jackson Hole depended on this scrubby little shrub from November through February to survive the famously long winters in the valley.

December normally produces up to thirty or so moose for me in a day’s search here. That year, however, there were none to be found as the moose had been forced to transition to their late winter haunts. There, the quality of browse is so low that moose stay in a caloric deficient despite eating all day. This is why the bitterbrush is so important to them beforehand, especially the for the bulls who are desperately trying to replenish fat reserves after the rut. How many of the valley’s moose starved last winter because of this, I don’t know. But elsewhere across Wyoming, mass die-offs of animals were well documented.

In all, a full 50% of the pronghorn population in Wyoming died of starvation in 2023. For mule deer, it was even worse with an estimated 70% being killed. Most species of ungulates (hoofed mammals) saw 100% fatality of fawns and calves that had been born that summer. Animals that live in places like Wyoming and Montana are well adapted to cold and snow. But eventually the snow became too much, too deep. And slowly but surely, the ungulates across the region could no longer dig deep enough to find food.

But when it came to bighorn sheep, 2023 was one of the best years I had seen in a long time.

Bighorn sheep are a species that is no stranger to extreme weather. Most populations of the Rocky Mountain bighorns (there are other species of bighorns such as the Desert and the now extinct Audubon’s) eke out a living above the treeline. In their lofty perches above 10,000 feet in the mountains, the alpine meadows these mountain sheep inhabit are in a perpetual state of spring throughout summer. Thanks to the elevation, however, it’s not uncommon for a storm to come rolling through in August that dumps 3 feet of snow. And to survive such events, to live on the knife edge of such extremes, a species needs to have a few tricks up their sleeve.

Back in Alaska, I had long since given up on trying to find and photograph species such as great gray owls around the valley where I lived. With so much snow on the ground, mixed with a few layers of ice in the middle from when temperatures had risen into the upper thirties for a several days, these owls could not survive in such conditions. But the sheep were a completely different story.

Bighorns and thinhorns (Dall and stone sheep) all have one thing in common: they are obsessively compelled to use very specific locations in the summer and winter year after year. Mountain sheep are not species known for wandering about and exploring new territories. While they may adapt to weather conditions, they do not adapt well to a change in venue. Build houses where they want to be in the winter, and you will have sheep in your yard. Cut off access to that location, and the whole population will likely starve to death.

Despite there being many feet of snow on the mountain in the background, the southwest facing slope where I found this truly massive bighorn ram in the winter had only patches of snow. So dry was this area that you can see cacti growing beneath the ram. Understanding how animals seek out and utilize microhabitats to survive the winter will give you an edge in your photography by helping you predictably find and photograph wildlife all winter long.

Wintering grounds for sheep are based on their knowledge of geography and weather. Anyone who has lived in mountains knows well that every valley, every ravine, every slope holds its own unique microclimate. Year after year, some places will always have significantly more snow, other places will always be colder, and others always have little to no snow, lots of sunlight, and nearly constant wind.

These microclimates are not lost on the wildlife of the region. Microclimates often mean the difference between life and death. And the critical wintering habitat of mountain sheep is always going to be a place that predictably receives the most amount of light and the most amount of wind in the winter: southwest facing slopes.

These sheep live in the northern hemisphere, a place where the sun is always somewhere in the southern sky. But afternoons are the warmest part of the day when the sun is to the south and west. And therefore, southwest facing slopes are exposed to more warmth and solar radiation than any other places in the mountains.

But there is more.

Wind in the mountains is what happens thanks to uneven heating across the Earth. When one place nearby is warmer than another, the less dense warm air rising creates a vacuum that pulls air from the colder place to fill the vacuum. Lower elevations tend to warm faster than snowcapped mountains. Southwest facing slopes baking in the sun warm faster than elsewhere and all of this translates to wind. Wind blows snow, quickly reducing three feet of powder to three inches when a windstorm kicks up.

For this reason, mountain sheep both summer and winter in locations where sun, warmth, and wind combine to create a microhabitat that is guaranteed to always have the least amount of snow. And it’s no coincidence that the Dall sheep hotspot outside of Anchorage, Alaska, happens to be called Windy Corner.

This guaranteed access to winter food is what creates the extraordinary predictability of mountain sheep in the winter. Year after year, century after century, sheep return to the exact same hillside each winter because that is the location where they know can survive the harshest of conditions. Windchill factor be damned, you can grow bigger or pack on more fat to handle cold. The real limiting factor for animals in snow is the ability to access food.

Mountain sheep are not the only species who have figured this out, of course. Where these conditions exist (southwest slopes + sun + lots of wind), other animals congregate as well. In the Greater Yellowstone Ecosystem, for instance, it’s no coincidence that elk and mule deer are often found overwintering in the same places as bighorn sheep.

But most people who read this article live nowhere near bighorn, Dall, or stone sheep, of course. So, this begs the question of how understanding mountain sheep in the winter translates to you being able to find and photograph wildlife this season?

Winter creates the same challenges on all species: how to find food and how to stay warm.

While mountain sheep may have evolved extraordinary adaptations and behaviors to solve these problems, it doesn’t mean that every other animal on the planet isn’t also trying to do so in similar ways to the best of their ability.

If you live in a place where snow accumulates in the winter, even if only for a few days or weeks at a time, there are areas around you that will always have significantly less snow, or perhaps no snow at all. Conifer trees (e.g. pines, spruce, firs, junipers, and cedars) famously produce more heat and shallower snow depths than deciduous trees, and every species around you knows this.

Maybe you never see snow in the winter and your only weather-related consideration for the season is temperature. What is cold is always relative. Cold tolerances for a caribou are different than that of an alligator. So, whether you live in Sarasota, Florida, or Seward, Alaska, species experience cold relative to where they are. It’s your job as a wildlife photographer, and therefore a naturalist, to pay attention as you move about life and recognize those areas where the sun beats down longer, and temperatures are even just a little bit warmer. Even a farmer’s field has a north and south facing treeline with subsequent microclimates that influence birds and mammals alike.

I think this is one of the things that appeals to so much about photographing wildlife in the winter. The season forces me to become even more observant as I piece together the puzzle of a habitat or ecosystem. And in doing so, I find a deeper knowledge and understanding of the natural world around me.

As for the photograph of the Dall sheep, thus far it was the accompanying photo of a ram along a patch of snow free and lichen covered rocks that has been my favorite this winter.

For me, it’s the contrast. When juxtaposed against the dark rocks and red-colored lichen, the white coat of this ram really pops. As much as I love photographing animals in the snow, the white of Dall sheep’s pelage just blends into the environment making it more challenging to create artful images that grab our attention. To really make this work, you need something more. Howling wind and blowing snow would absolutely fit this bill and tell a great story about the species at the same time (important stuff if you want to sell your work to magazines).

And for me, this is exactly what I hope to focus on when I make it back up to Alaska after my Yellowstone workshops this winter.

- Jared

P.S. If you are enjoying these articles about weather's impact on wildlife and how we can use that knowledge to predictably find and photograph animals, then make sure you check out my feature article about this very topic in the upcoming Winter issue of PhotoWILD Magazine.

Uncompromising quality. Workshop level education. The Art & Science of wildlife photography at your finger tips.

Already a subscriber? Login Here