“The times they are a changin’ …’” wrote a certain Mr. Zimmerman (aka Bob Dylan) and for the members of the natural world here in South Burlington, as well as all around the world, these changes can create some serious problems. Existential problems, you might say.

One type of problem faced by many species of animals and plants and other organisms is the loss and fragmentation of their habitats. Unlike we humans, who through our technological prowess seem to be able to live almost anywhere (more on this later), other species have specific tolerances to environmental conditions and specific resource needs in order to survive. When human activities such as roads and housing developments and malls and farms and mines break apart tracts of these habitats, different species may find their homes inadequate to support them.

Here are a couple of examples of how fragmented habitats can threaten species. Take predators, as an example. Sitting atop the food chain, they often need large patches of habitat to provide adequate prey for them to feed on. If you’re a bird predator, you can fly from patch to patch to find enough food, but if you locomote on land, something like a highway or densely populated area might prevent you from getting to enough natural habitat to survive.

Here’s where the concept of wildlife corridors comes in. If a predator has even a narrow corridor in which to travel from patch to patch, it may have access to enough territory to thrive. So, as we continue to develop South Burlington for our ever-increasing human needs, it is important to preserve these critical corridors so that wildlife can continue to coexist with us.

Another example of how fragmentation can threaten species is when species have life cycles that require two kinds of habitats. Amphibians such as some frogs and salamanders live in the leaf litter on the forest floor during their adult stages. But each spring, they march to a nearby vernal pool to mate and the juveniles develop in these temporary ponds until they become adults that then disperse back into the woods. If the path to the pool gets blocked by some human activity, then that species may be doomed to local extinction. Some forward-thinking communities have actually built amphibian underpasses or overpasses over roads to allow the amphibians to survive.

Perhaps even more threatening to many species is the warming of the planet and disruption of climate. Most species have limited temperature tolerances, and as climate warms they need to either move toward the poles or up the mountains, or quickly evolve new tolerances (very unlikely). Some types of animals and plants can change their range quickly – think animals that can migrate and plants whose seeds can be carried by wind and water and animals. But many species can’t move this fast and won’t be able to “outrun” the changing climate.

Here too, species on the move will need corridors to relocate. Mobility is key. Are there human made obstacles that prevent a species from shifting its range? Can we as a community, as a state, and as a country (in actuality, a community of countries) have the foresight to provide for the creatures with whom we share this planet?

Speaking of foresight, we as a species, even with all our technological capabilities have limits to what we can or will tolerate. In a world of climate warming and instability, human habitats now fraught with heat waves and droughts, floods and coastal storm surges, wildfires and sea level rise will result in huge human migrations as this century progresses. Will South Burlington be ready for an influx of environmental refugees from the East Coast? Will refugees around the globe find safe corridors of passage to livable habitats?

Fred Kosnitsky has been teaching biology, ecology, and environmental issues at Community College of Vermont over the past 35 years. He is a member of the inaugural class of the South Burlington Master Naturalist Program. You can contact him at fredkosnitsky@yahoo.com with suggestions for future columns.

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