Researchers find concerns for animals tied to same habitats

A team of researchers led by scientists from the University of Wyoming and the University of Washington has reviewed the scientific literature and found that, while this "consistent" behavior may be beneficial when environmental conditions don't change very fast, those benefits may not be realized in the ever-changing world dominated by humans. The research was published today (Tuesday) in the scientific journal Frontiers in Ecology and the Environment.

Ecologists use the term "site fidelity" to describe the behavior of animals that are stuck in their ways. Site fidelity is the tendency to return to previously visited locations and is common across many species, from fish to birds to mammals and insects. Think salmon returning to their natal streams to spawn, or birds returning year after year to the same nest site -- site fidelity is all around us in nature.

As animals become familiar with a place, site fidelity can help them know where to find good food or hiding spots from predators, and can help them move efficiently to and from these resources. However, the authors uncovered an emerging theme in the scientific literature.

"Animals that have strong site fidelity are having a tough time adjusting to the novel landscapes that are showing up around them as a result of humans," says Jerod Merkle, an assistant professor at the University of Wyoming and the co-lead author of the paper.

The broader message of the paper suggests that, when confronted by human disturbances or climate change, animals with strong site fidelity may not survive or reproduce as well as animals that have more flexible behaviors. When populations consist of many site-faithful individuals, this can lead to population declines.

In Wyoming, for example, large natural gas fields have been developed in several mule deer winter ranges. Although mule deer can make small shifts in their range to avoid infrastructure, they remain faithful to the same general area rather than abandoning it entirely. Their continued use of those degraded areas following development can have negative consequences. In one long-term study, researchers found a 40 percent decline in the mule deer population following large-scale energy development in their winter range.

This also is playing out as a result of climate change. In female northern elephant seals in the Pacific Ocean, site fidelity is a winning strategy under normal climate conditions. In typical years, site-faithful seals are better able to find food and put on fat than their more flexible counterparts. But, when abnormal climate conditions such as extreme El Niños cause big changes in the ocean ecosystem, behaviorally flexible seals become the winners, and female seals with strong site fidelity are not able to gain as much valuable fat that they need to reproduce.

"Despite each of us working on very different species from one another, our group came together because we all recognized that there was a clear connection between strong site fidelity and species declines," says Briana Abrahms, an assistant professor at the University of Washington and the other co-lead author. "We all thought it was important to call attention to this connection for other researchers and wildlife managers. Recognizing the types of species or behaviors that may suffer most from human-induced environmental change can help develop conservation priorities and actions."

While the authors' synthesis provides a grim sketch of the future for species with strong site fidelity, they also provide an upshot.

"While these species appear to be stuck in their ways, many of them also have some unique but subtle ways of dealing with change," says Jonathan Armstrong, an assistant professor at Oregon State University and co-author of the study.

Every once in a while, an animal does something new, and it works. While such cases are rare, those "innovators" can be key to persistence in changing landscapes.

"We just have to be patient and make sure populations don't crash before such innovators come along," Armstrong says.

The authors conclude with a number of suggestions for researchers and practitioners. First, long-term monitoring is key to see how individuals and populations respond to change. Second, they suggest that biologists should not expect animals to always use and find the best habitats. This is especially important for restoring new habitat areas, which may not work all that well for species with strong site fidelity because they may not "find" these restored habitats.

Because of this, the authors thirdly suggest that conservation of species with high site fidelity focus on protection and restoration of highly used sites, rather than off-site mitigation.

Other authors of the paper are Hall Sawyer, of Western EcoSystems Technology Inc. in Laramie; Daniel Costa, of the University of California-Santa Cruz; and Anna Chalfoun, of the Wyoming Cooperative Fish and Wildlife Research Unit at the University of Wyoming.