DelVal welcomes new arrivals from Purdue University

Jun 28, 2012


While most people get the heebie-jeebies just thinking about rats, officials with the Pennsylvania Game Commission and Delaware Valley College are excited about the recent arrival of 11 rats – Allegheny woodrats, to be specific – and what these animals will contribute to animal research efforts and the genetic diversity of the state’s native woodrat populations.

After an all-night road-trip that started at Purdue University, in West Lafayette, Ind., seven female and four male woodrats arrived on campus June 21.

The woodrat has been a state-listed threatened species since 1983, and shouldn’t be confused with the Norway rat, which is the world’s proverbial poster critter of filth that originated in northern China and now inhabits every continent, as well as every Pennsylvania county. In fact, woodrats are a relative of the better-known packrats of the western United States, and are important to Pennsylvania.

Woodrats, beginning in mid-summer, store food for winter by stuffing leaves and other materials into rock crevices and protected ledges. They also collect non-food items such as wasp nests, bones, molted snakeskins, candy wrappers, and shotgun shells.

“Woodrats, like bald eagles, are one of our best and last indicators of true wilderness,” said Carl G. Roe, Game Commission executive director. “They are confined to Pennsylvania’s ridges, and, as those ridges are developed, woodrat communities often become ghost towns, historical markers of what once was. Most people won’t miss them. In fact, most didn’t even know that they were out there. But woodrats are significant. They are a species of greatest conservation concern that the Game Commission’s Wildlife Action Plan has designated as in immediate need of assistance.

“Because they are specialists at surviving in remote, rocky forested landscapes, woodrats provide a mechanism of monitoring the health of these unique and fragile ecosystems.  The woodrats decline is a red flag, and we are seeking to reverse the trend.”

At one time, woodrats were found in 41 Pennsylvania counties, but the 20th century’s American chestnut blight and gypsy moth invasion — other imports from Asia — and substantial changes in land use have conspired to create huge habitat deficiencies and insurmountable barriers in the woodrat’s world. Today, woodrats can be found in a couple dozen or so mountainous counties, and their population centers usually are surrounded by vast stretches of inhospitable and uninhabitable lands that they have little chance of traversing to reach other woodrat-friendly environs.

Although it is referred to as a “rat,” the woodrat is more mouse-like in appearance and has a bicolor, furred tail – unlike the naked tail of the Norway rat. It also is distinguished by noticeably larger ears and eyes, a larger, heavier head, and much longer whiskers. It is gray above with white underparts and paws. The average adult weighs less than a pound and measures 17 inches, including an eight-inch tail.

So, what benefit will a mere 11 woodrats have for the wildlife populations here in Pennsylvania? And, why are they coming from Purdue University to Delaware Valley College? 

The woodrat colony, after serving a similar role at Purdue University, will live in a lab on campus in a state of permanent quarantine with limited direct access because of concerns about stress and the health of the animals. The primary goal of the colony will be to produce as many offspring as possible in support of conservation efforts by the Game Commission.  Offspring may be used to augment declining woodrat populations, or re-establish colonies where they have been lost.

“These woodrats will enable us to create a link between our students’ education in the classroom in wildlife conservation, small animal and zoo sciences, and a regional conservation priority species” said Reginald Hoyt, assistant professor and Animal Biotechnology and Conservation Department co-chair.  “In our zoo science classes, students will be tasked with designing natural habitat enclosures and exhibits appropriate for a colony of woodrats, as well as improving animal care protocols that promote reproduction. We also will look to incorporate a live-webcast, in partnership with the Game Commission, from a naturalistic exhibit for others to learn about woodrats.

“Students in other animal and pre-veterinary courses will be able to benefit from this colony by learning about nutrition and reproduction, behavior research and genetic work, which will be conducted in partnership with Purdue University and other collaborators. We also will be able to work on developing artificial insemination techniques for difficult breeders, and our small animal science teams will be able to study the effects of raccoon roundworm, which is one of the suspected causes of the decline in wild woodrats.”

Hoyt noted that DelVal will seek to maintain a colony with a projected maximum number of 25 animals. So, as the colony produces offspring, the juveniles will be handed over to the Game Commission for release into the wild.

“Delaware Valley College will work with the Game Commission to develop a soft-release protocol for juvenile woodrats produced by this colony,” said Dan Brauning, Game Commission Wildlife Diversity Division chief.  “These releases are by no means expected to increase the number of wild woodrats, but the genetic diversity that they will provide to our wild populations will be important to maintaining healthy wild populations.”

Brauning noted that the agency already is considering two potential release sites, such as State Game Land 211 in Dauphin, Lebanon, and Schuylkill counties, as well as the Lehigh Gorge in Carbon County.

“Woodrats live on islands of rock, and are tied to geology for denning sites and forest composition for food and cover,” Brauning said. “If woodrats encounter trouble on one ridge, it becomes next to impossible for the colony to pick up stakes and move to the next ridge.

“It might take a woodrat population 20 to 50 years over many generations to shift 20 miles in reasonably good habitat. If the habitat isn’t good, the woodrat has to cross a valley, or an interstate highway or suburbia – where there’s no cover or food – but plenty of predators. It’s like walking the plank.”

The woodrat, like the opossum, is a living fossil. It has inhabited the rockier sections of the mid-Atlantic states since the days of the wooly mammoth. Given its preferences, the woodrat had its habitat market cornered for centuries upon centuries; few other creatures prefer to live on boulder-strewn ridges and talus slopes. But now, after thousands of years, this creature’s existence is threatened.

“Greater than 5 percent of the world’s breeding population of woodrats is found in Pennsylvania, which means the Commonwealth has a global responsibility to help protect and manage this species, holding onto both the woodrat’s retreating northeastern range and the nuclei of healthy populations, including those on Chestnut Ridge,” Brauning said. “But, big population centers have disappeared since the 1970s, including those on the Blue Mountain, from Dauphin County east to the Lehigh River, and near Kennerdell in Franklin County overlooking the Allegheny River.”

With a lifespan that is generally about 18 months, woodrats pretty much grow and go. Males usually have shorter lives — probably related to pitfalls of dispersal. Woodrats are active year-round, primarily vegetarian and seem to peacefully coexist among the rocks with timber rattlesnakes and copperheads. They have two to three litters of young, beginning in April.

For more about the woodrat, visit the Game Commission’s website, put your cursor over “Wildlife” in the menu bar at the top of the homepage, click on “Endangered” in the drop-down box then click on “Allegheny Woodrat” in the “Threatened Species” listing.