Climate impacts to the winter wildlife community

Ben Zuckerberg and Jonathan Pauli are associate professors in the Department of Forest and Wildlife Ecology at the University of Wisconsin-Madison.

Can you give us an overview of what’s been happening with wildlife and climate change?

Ben: What we have seen over the past 40 to 50 years clearly has been a pretty significant shift in the climate system. Species are responding to that in a number of different ways, from changes in their phenology and migration patterns to shifts in their distribution and ranges, especially northward. Impacted species encompass not only what we consider the cold or winter adapted species that are moving northward, but also warmer adapted species moving northward and colonizing Wisconsin over the last 40 years or so.

That shift is happening already?

Ben: Yes, we have been able to document the shift in various different ways. A good example is the snowshoe hare. Since the 1930s, their range has slowly contracted northward. They are no longer common in areas where they were previously relatively more common. A number of species are showing that same shift northward.

Is this a big shift that is happening? Or is it just a few species that are moving?

Ben: The shift northward is considered a global fingerprint of climate change, meaning we are seeing it here in Wisconsin, we are seeing it in North America, and throughout the world. One of the indicators that it is climate change is the fact that many of the species are showing the same pattern over the same time period.

What is happening with ruffed grouse as the climate warms?

Ben: Grouse are winter adapted birds. They are a popular game bird and an emblematic Wisconsin bird associated with the northern forests. They do this crazy behavior, where they will roost under the snow. We found that when they are able to roost, in at least eight inches of snow, they get two benefits. One is that they avoid predators, and two, it’s actually kind of warm, like a blanket. When they have that snow blanket, it decreases their stress levels and they survive the winter better, in comparison to the grouse that don’t have access to the snow.

In some ways ruffed grouse and snowshoe hare are the sentinels of the winter wildlife community. Just like snowshoe hares, ruffed grouse populations have been declining. We are interested in understanding the stressors on their populations, in addition to the changing winter and lack of snow cover.

Jon, could you talk about the snowshoe hare and what has been happening?

Jon: The snowshoe hare is an ideal species to begin to look at some of those shifts that Ben was talking about. Every year snowshoe hares turn white in the winter to match the snowy background and effectively camouflage against all of the species that kill and consume them. In spring they turn to brown. As snow cover season is declining in terms of its duration, snowshoe hares are increasingly mismatched, especially around their current southern range boundary. This mismatch means they are white on a brown background and are more vulnerable to predation. We have seen dramatic range shifts in snowshoe hares. We estimate that they are moving northward at about 8.5 kilometers per decade.

What mechanisms are being looked at to help these species survive?

Ben: One real strategy is habitat management. Forestry and forest management can help buffer some of these species that are no longer matching the environment because of climate change.

Jon: Managers can’t create snow and they can’t stop climate change, but there are other opportunities that can help. One of the things that we have done very effectively in wildlife ecology and conservation biology for decades is to understand species habitat relationships, and actively manage the habitat to try and promote that species. We are advocating the idea of focusing the lens of habitat management through climate change and managing habitat to buffer the consequences of climate change.

For example, one of our past graduate students, Evan Wilson, saw that a mismatched hare, a white snowshoe hare on brown background, had a higher probability to be killed by a predator than a hare that was white on top of snow. However, we also noticed that if the mismatched hare was in a young aspen or alder thicket, it is easier for them to hide from predators and they achieve the same survival rate as the matched snowshoe hare. This is one example of the ways in which we could think about managing habitat to try to offset, at least in some places and at some times, the negative consequences of climate change on species.

Why should people care about species like this, and that the wildlife is moving and shifting ranges?

Jon: These are species that many of us who have grown up in this region are familiar with and expect to see when we go hunting or hiking or photographing. The idea that we are losing these native species is sad to us. For me, Northern Wisconsin without snowshoe hares will feel incomplete, and I think it would be the same to many others.

Also, when we lose a single species, we begin to disassemble a community. These are animals that have coevolved and interact in interesting and sometimes unexpected ways. When we pull out one of those individual species from a community, that incomplete community now behaves in a different, unpredictable way. Often when we lose one species there are others that fall behind it. Even if you don’t care about snowshoe hares, there can be consequences on other organisms that inhabit the same community, like fishers or porcupines. No single species exists in a vacuum. Losing a single species has rippling effects on the broader community in ways that we cannot predict.

What can individuals do to help wildlife?

Ben: I have always been a proponent of citizen science and enlisting the public for scientific research and data collection. If it wasn’t for these programs, we would have a lot less to say about the ecological impacts of climate change. People from all walks of society can participate.

Jon: Another idea is to educate yourself. There’s so much out there from the state, universities, and popular literature. I would encourage people to dig in and get involved.

Do you have hope for the future?

Jon: Yes. When it comes to the conservation of ecological communities and species in the face of climate change, I do have hope. I have hope because there’s an increasing groundswell of people realizing how important this is and because I am getting interviews like this, where we are able to reach out to the public. And I am hopeful because people like Ben and I are beginning to come up with creative solutions based on fundamental research and understanding how species respond to climate change.

Ben: I share Jon’s hopefulness, not just at the local and state level but in the nation and as a global conversation as well. Just look at how the conversation has evolved. Thirty years ago, people wondered if climate change was really happening, then it moved to “yes, it’s happening but are humans causing it?” Now the conversation is “humans are causing it, what can we do about it?” I think the societal conversation is certainly heading in the right direction. I am hopeful that the rate of societal change will only increase.

The views and opinions expressed in this interview are those of the authors and do not represent official policy or position of the University of Wisconsin-Madison or the Wisconsin Initiative on Climate Change Impacts.