WSB: At Shenandoah, park visitors and woodrats coexist

The Allegheny woodrat (Neotoma magister) is threatened or endangered across much of its geographic range, but it’s found a refuge in Virginia’s Shenandoah National Park, which has plenty of rocky outcrops, which they favor, and hardwood forests, which they rely on for food. But the same rock outcrops that woodrats occupy can also be popular with park visitors. Could that negatively impact woodrats in a park the otherwise seems to protect them?

It doesn’t seem to, according to a recent study published in the Wildlife Society Bulletin. Using remote cameras, researchers found that the woodrats — commonly known as packrats — were relatively tolerant of human hikers and rock climbers using the outcrops, and the researchers found populations of woodrats in parts of the park where they hadn’t been known to exist before.

A remote camera captures an Allegheny woodrat in Shenandoah National Park. Image courtesy of Jason V. Lombardi.

“Some of these outcrops were in what you would call pristine areas where there was little human influence, but some were the most popular tourist spots in the park,” said Jason V. Lombardi, the lead author of the study, which was funded by the Piedmont-South Atlantic Cooperative Ecosystem Studies Unit of the National Park Service. “The woodrats colonize these areas regardless of human presence, which corroborates previous studies that suggested woodrats are more tolerant of human disturbance.”

Woodrats are habitat specialists, known for their middens of twigs, sticks and often human artifacts, which have earned them their nickname. Woodrats have small litter sizes and occur in metapopulations across their range. Their populations have declined over the past 40 years in the central Appalachian Mountains, in part because of loss and fragmentation of oak and hickory forests and which has affected gene flow across the region. Populations are also vulnerable to overly abundant raccoon (Procyon lotor) populations.

That has made Shenandoah National Park an important place where woodrats could persist, Lombardi said. They were known to exist in northern and central parts of the park. But after Lombardi and his team set up camera traps at outcrops throughout the park, they found populations in southern areas, too.

“That alone will help park biologists continue to monitor the populations,” said Lombardi, a TWS member who is now a PhD candidate and the Betty and George Coates Fellow in Habitat Research at the Caesar Kleberg Wildlife Research Institute at Texas A&M University-Kingsville.

His research didn’t include population estimates, but the finding suggests that the park may have a higher number of Allegheny woodrats than park biologists had believed, he said, and it opens the door to new genetics research to gauge gene flow between the populations.

Forest cover is critical to maintaining the woodrats, though, Lombardi found. Pine forests on the dry south-facing slopes of the national park lack the food resources for woodrats to persist long term, he said, which emphasizes the importance of conserving hardwood forests.

“We need to protect and preserve areas where you have rock outcrops, which is a sensitive ecosystem on its own,” Lombardi said, “but we really need to preserve the oak-hickory forest to help the long-term persistence of woodrats.”

TWS members can log in to Your Membership to read this paper in the Wildlife Society Bulletin. Go to Publications and then Wildlife Society Bulletin.