Researchers at the University of California, Davis have developed a methodology that they say can help identify the most important wildlife corridors to keep open in a cost-effective and timely manner.

In a study summarizing their results published in the journal PloS one, the authors note that wildlife populations that are isolated due to not having access to corridors that allow them to move between protected areas can suffer from compromised genetic variability and are less able to shift their range in response to global climate change.

The researchers used what they describe as “least-cost methods” to develop a methodology for assessing wildlife corridors at a national scale, which they then applied to Tanzania as a case study.

As local wildlife populations around the world are increasingly forced to rely on reserves hemmed in by agricultural land, urban areas, and other human developments, it’s more crucial than ever that we keep corridors open between protected areas. So researchers at the University of California, Davis have developed a methodology that they say can help identify the most important wildlife corridors to keep open in a cost-effective and timely manner.

In a study summarizing their results published in the journal PloS one, the UC Davis researchers note that wildlife populations that are isolated due to not having access to corridors that allow them to move between protected areas can suffer from compromised genetic variability and are less able to shift their range in response to global climate change — all of which makes it that much harder to save a species from extinction, if and when it comes down to that.

“The long-term viability of wildlife species relies on maintaining connectivity between protected areas,” Jason Riggio, a graduate student in UC Davis’ Department of Wildlife, Fish and Conservation Biology and lead author of the study, said in a statement. “Large-scale conservation corridors can serve as essential linkages between habitats.”

Riggio and coauthor, UC Davis professor Tim Caro, used what they describe as “least-cost methods” to develop a methodology for assessing wildlife corridors at a national scale, which they then applied to Tanzania as a case study. By combining up-to-date data on land conversion in East Africa with interview data on wildlife corridors, they hoped to determine which of Tanzania’s wildlife corridors might still be open (referred to as the corridor being “structurally connected”), which corridors have been closed off due to conversion of the land for human purposes, where any other potential wildlife corridors might be located, and which protected areas with lower levels of protection, such as forest reserves and wildlife management areas, could serve as crucial links between more fully protected areas like national parks and game reserves.

Essentially, what Riggio and Caro did was look at land conversion patterns to model corridors that could be used by wildlife to move between Tanzania’s protected areas, then interviewed locals to determine whether or not the corridors they had discovered were actually useful to local animal populations. “Interviews with people living within or adjacent to wildlife corridors can provide accurate information on wildlife movements that can be obtained fairly easily,” Caro said in a statement. “These data can then be used to validate connectivity models.”

He and Riggio found 52 intact corridors connecting protected areas in Tanzania, 23 more than had been identified by official surveys the Tanzanian government conducted in 2009. They also discovered that 21 of the 24 corridors that the government report stated were likely to have already been severed were actually still structurally connected.

“Nonetheless, nearly a sixth of all the wildlife corridors identified in Tanzania in 2009 have potentially been separated by land conversion, and a third now pass across lands likely to be converted to human use in the near future,” Riggio and Caro write.

There are still some east-west corridors connecting protected areas, the researchers add, but there are no open wildlife corridors linking protected areas in northern and southern Tanzania, while two reserves — Gombe Stream National Park and Pande Game Reserve — were found to now be completely isolated.

However, Riggio and Caro did discover two reserves with lower levels of protection, Uvinza Forest Reserve in western Tanzania and Wami-Mbiki Wildlife Management Area in the eastern part of the country, that act as “crucial stepping-stones” between national parks or game reserves and therefore deserve to be the focus of increased conservation efforts.

“While most people will never have heard of these small reserves,” Riggio said, “they are absolutely vital for linking larger parks.”

While other methods for identifying wildlife corridors worthy of heightened conservation, such as fitting animals with GPS collars, can be cost-prohibitive and limited to smaller spatial scales, Caro said that the methodology he and Riggio developed is much more cost-effective and can be done at the national scale. That’s important, he says, because as connectivity between protected areas continues to erode, new methods for quickly and cheaply determining where wildlife corridors still exist are essential.

“Our method of modeling landscape connectivity using spatial data on anthropogenic land conversion, combined with interviews to validate these models is readily applicable to other regions,” Caro said. “We need to identify wildlife corridors very rapidly before they disappear.”

CITATION

Riggio, J., & Caro, T. (2017). Structural connectivity at a national scale: Wildlife corridors in Tanzania. PloS one, 12(11), e0187407. doi:10.1371/journal.pone.0187407

Follow Mike Gaworecki on Twitter: @mikeg2001