Terrestrial connectivity loss (roads and development)

Animal movements are important for a variety of reasons and at a wide range of scales. Individuals move to seek food or shelter, escape predators or unfavorable environmental conditions, and find mates or suitable breeding habitat. At the population level, dispersal, either as juveniles or adults, serves as a mechanism for regulating population densities. Multiple local populations are often interconnected via the occasional movements of individuals from one population to another. These regional populations, also known as metapopulations, are generally able to persist over much longer time periods than are local populations.

The flow of animals from one area to another can rescue (supplement) local populations whose reproduction cannot keep up with mortality. Movements of animals from one population to another can also help maintain healthy genetics in small populations that would otherwise tend to lose genetic variability over time. And when local population extinctions do occur, the movement of animals across the landscape provides opportunities to recolonize vacant habitat and reestablish populations.

Physical barriers, lack of cover, and vehicular traffic are just some of the difficulties that wildlife face when they seek to cross roads and highways. Photo credit: Scott Jackson

Over long periods of time, populations of plants, animals and other organisms have shifted their locations along with changing environmental conditions. As glaciers advanced across New England and then retreated north again, populations shifted south and then, slowly, over the course of millennia, reoccupied areas that had been previously covered by a thick sheet of ice. Global warming is causing our climate to change much more rapidly than at any time in recorded history. We can expect similar shifts in the distribution of plants and animals – but only if they can readily move through the landscape.

Human development, especially roads, has fragmented the terrestrial landscape to a significant degree. Roads and railroads may have small footprints compared to other types of development but they stretch out across vast distances. Some animal species are unwilling or unable to cross paved roads. Others are highly vulnerable to roadkill that can lead to population declines. Habitat fragmentation and barriers to movement have been an acknowledged problem for wildlife conservation for decades. With the prospect of ongoing and future changes in climate, maintaining or restoring terrestrial connectivity will be an essential adaptation strategy for dealing with climate change.

References

Adapted from

Staudinger, M.D., A.V. Karmalkar, K. Terwilliger, K. Burgio, A. Lubeck, H. Higgins, T. Rice, T.L. Morelli, A. D'Amato. 2024. A regional synthesis of climate data to inform the 2025 State Wildlife Action Plans in the Northeast U.S. DOI Northeast Climate Adaptation Science Center Cooperator Report. 406 p. https://doi.org/10.21429/t352-9q86

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