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PNW Pacific Northwest Research Station Inside Sheep Grazing, Predator Control, and ...... 2 A Long Trek ...... 3 Mountain , Valley Fox ...... 4 A Hopeful Remnant...... 5 FINDINGS issue one hundred thirty two / April/May 2011 “Science affects the way we think together.” Lewis Thomas

Tracing the Fox Family Tree: The North American Has a Diverse Ancestry Forged During Successive Ice Ages

IN SUMMARY The red fox is one of the most wide- spread and adaptable on Earth. In the American West, however, there are populations of native red Danand Cindy Hartman that occur only in alpine and subalpine , which may be at risk from human-caused and natural pressures. One potential threat is global climate change, which is likely to reduce both the amount and connectivity of suitable for these unique red foxes. Until recently, the evolutionary history of native North American red foxes, which also occur in the boreal forests of and , was largely speculative. As a doctoral student in the early 1980s, Keith Aubry, now a research North American red fox populations originated from two separate genetic lineages that were isolated wildlife biologist with the Pacific nearly half a million ago by advancing glaciers. Northwest Research Station, con- ducted an intensive study of North he red fox ( vulpes) is the translocated from other regions for or American red foxes, especially the most widespread land in the farming, or those that may have colonized montane populations. Based on T world. The inhabits much of these areas from nearby native populations. , archeological, historical, and this continent, , , and the northern ecological evidence, he hypothesized But not all red foxes fit that picture. Other extremes of Africa. It is found in , tun- that contrary to prevailing theory, lesser known populations of red foxes live in dra, woodlands, meadows, pastures, suburbs, native red foxes arose from two distinct high-elevation alpine and subalpine habitats and cities. lineages that had been isolated from in the , Sierra , and each other during the last glaciation. Red foxes often serve as heroes or villains in . These foxes have inhabited Using modern molecular genetics, a folktales and songs. They are portrayed their cold, isolated environments since the last team of researchers led by Aubry has as wily and cunning survivors that are Ice Age. Shy occupying a forbidding confirmed his hypothesis and revealed well-adapted to human ways—prone to raid world, they are not well-adapted to humans. important new details about the evolu- farmers’ chicken coops, steal pet food, and Highly elusive, they are rarely sighted and tionary history of North American red raise their pups under deserted shacks. That even more rarely studied. foxes. Their analyses provide the stereotype may fit the foxes most people see, At least one of these native populations, the foundation for revealing the red fox’s the ones that thrive in many low-elevation, mountain-dwelling red foxes in the Sierra genealogy at finer levels, and aids human-dominated environments of North Nevada (V.v. necator), has suffered signifi- conservation efforts by making it America. Many of these populations come cant range losses over the past century. They possible to distinguish native from from multiple sources, including red foxes have apparently been extirpated from much nonnative populations, and identify those that may be threatened. of their historical range, which once extended there’s a critical lack of reliable information the biggest cause for concern right now,” says from the southern Cascades down to Mount on their current distribution and conserva- Aubry. “If a biologist or manager asked me Whitney in the southern Sierras. tion status. Aubry is a Forest Service research about the of montane red wildlife biologist who has studied red foxes foxes in most parts of their range, I could only Montane red foxes may be threatened in other and other high-elevation for more say that we simply don’t know.” portions of their historical range, but no one than 30 years. “Those knowledge gaps are knows for sure, says Keith Aubry, because SHEEP GRAZING, PREDATOR CONTROL, AND CLIMATE CHANGE n high mountain meadows, sheep ranch- these montane red foxes may be threatened In 2009 Aubry, Perrine, and three other ers once routinely killed and by diseases spread by domestic (includ- researchers (Mark Statham and Samantha I other predators by lacing dead sheep with ing and ), run-ins with Wisely of Kansas State University and poison; red foxes were probably among the cars, and by a warming climate. Benjamin Sacks of the University of victims. Historical overgrazing may also have at Davis) published a breakthrough Mountain-dwelling red foxes live on isolated depleted food for mice and pocket , genetic analysis that revealed important islands of cold, high country—shrunken the foxes’ primary prey. Trappers took Sierra details about the North American red fox’s remnants of habitat from the last Ice Age. Nevada red foxes for their pelts in the early ancient family tree. By analyzing DNA from If the Earth continues to warm, these islands days, but the of red foxes has been 285 museum specimens, Aubry and his team will shrink even further. Aubry’s colleague prohibited in California since 1974. Today, showed that the red fox lineage had split into John Perrine of California Polytechnic State two major family groups much earlier than University reported that by 2100, high- previously believed. elevation habitat in the could Purpose of PNW Science Findings be reduced by half or more. To provide scientific information to people who make and influence decisions about managing land. KEY FINDINGS PNW Science Findings is published monthly by: Pacific Northwest Research Station USDA Forest Service • Researchers used genetic analyses to reveal the evolutionary history of the North P.O. Box 3890 American red fox (Vulpes vulpes). Their work confirms that native populations Portland, 97208 originated from two separate lineages that were isolated nearly half a million years Send new subscriptions and change of address ago by advancing glaciers. information to: [email protected] • The team’s genetic analyses provide the basis for further work to clarify genetic relationships among native and between native and introduced populations Rhonda Mazza, editor; [email protected] of red foxes. It also provides the scientific basis for investigating potential genetic Cheryl Jennings, layout; [email protected] linkages to their unique ecological adaptations. Science Findings is online at: http://www. fs.fed.us/pnw/publications/scifi.shtml • Red foxes in the Sacramento Valley are a distinct and previously undescribed native subspecies that is closely related to the Sierra Nevada red fox (Vulpes vulpes necator). Forest The research team has named the Sacramento Valley red fox Vulpes vulpes patwin. Department Service of Agriculture

2 A LONG TREK any mammals colonized from Asia by cross- ing a land bridge that emerged near the as the M sea level declined during each Ice Age. This northern ice- free refugium, which included parts of , Alaska, and the , is known to paleontologists as . The red fox first reached North America during the Illinoian glaciation (300,000 to 130,000 years ago). Then, during the Sangamon interglacial period (130,000 to 100,000 years ago), red foxes expanded their range southward into what is now the . When Aubry was a graduate student, the prevailing theory for the mod- ern origin of red foxes in North America was that all were descended from animals that had been isolated south of the ice sheets (i.e., in the southern ice-free refugium, which included most of the contiguous United States) during the most recent Ice Age—the Wisconsin glacia- tion (100,000 to 10,000 years ago). Then, when the glaciers finally retreated, red foxes followed their cold-climate habitat upward in eleva- tion or northward in latitude, colonizing the montane and boreal habi- tats they occupied when European settlers first came to this continent. This series of maps shows how the advance and retreat of glaciers over That was the theory. But of the red fox discovered during the past 300,000 years influenced the evolutionary development and the 1970s in the northern refugium and the size of red foxes in dispersal of the red fox throughout North America. ’s Cascade Range when compared to those in western Canada didn’t fit. Modern-day Cascade fox are much smaller His flash of insight convinced Aubry that the existing theory was than those of the Canadian foxes even though their ranges are adjacent. wrong. Aubry dug into archeological and historical records and the This was a puzzling anomaly. If both of these subspecies had originated ecological literature. When he put it all together, he concluded that from a single northward migration after the Wisconsin glaciers retreat- North American red foxes were derived from two distinct lineages (also ed, Aubry reasoned, their modern-day skulls should be closer in size. known as ) that had diverged from each other while they were iso- lated in both northern and southern refugia during the last glaciation. “You would expect to see some differences among subspecies due to isolation and local adaptations,” he says, “but if they all originated from Aubry further hypothesized that the montane red foxes were unique, a single lineage that had expanded its distribution in a wave across the both in size and habitat affinities, because they were the direct descen- continent, you’d expect to see a more or less continuous gradient in dants of red foxes that had occupied the southern refugium during the size—a cline, as occurs among the northern red foxes from Alaska last glaciation, whereas the red foxes in were derived southeastward across Canada. Instead, there was an abrupt discontinu- from a wave of post-glacial migrations that originated in the northern ity in size between these adjacent populations, suggesting that the mon- refugium and spread southeastward across western Canada. tane red foxes had evolved in isolation from the northern populations.”

3 It was an elegant hypothesis, supported by data clearly showed, however, that the north- that time, says Aubry, but at the height of the considerable natural history data. But it was ern refugial red foxes were not part of the Wisconsin glaciation, the Great Plains was a unprovable until the advent of modern molec- original colonization of North America, but treeless, windswept —an extreme envi- ular genetics. were derived from a second colonization event ronment that was probably uninhabitable by that occurred during the Wisconsin glacia- red foxes and other boreal species. Now, that long-ago Eureka moment has been tion. That meant that the two North American confirmed by genetic tests. Just as Aubry When the Wisconsin glaciers melted, the lineages had split from each other almost half hypothesized, the main evolutionary stem foxes’ cold-climate habitat shifted to higher a million years ago, much further back in time forked into two major genetic lineages. “I elevations and more northerly latitudes. Red than Aubry had suspected. knew my hypothesis was strong,” Aubry says, foxes in the West (the Mountain subclade) “and our genetic analyses confirmed it in The team was also able to sketch in some of colonized the alpine meadows and subalpine almost every detail. That was very gratifying.” the finer details. At the height of the last Ice parklands in the high mountains, whereas Age, red fox populations that had been isolat- those in the Eastern subclade followed boreal There was one surprise, however. Aubry had ed in the southern refugium (the Widespread forests northward and colonized eastern and assumed that both the southern- and the north- subclade) had, in turn, become isolated in . At the same time, the north- ern-refugial red foxes were descendants of western and eastern portions of the refugium. ern or Holarctic foxes expanded their the original colonization event that occurred Pollen-core data provide only a sketchy range southward across western Canada, during the Illinoian glaciation. The genetic glimpse of the mid-continental landscape at meeting up with the eastern foxes in central Canada.

MOUNTAIN FOX, VALLEY FOX n a followup study, Aubry and his col- leagues investigated the evolutionary origins of the Sacramento Valley red fox,

I SherriLisius a lowland inhabitant. Because these foxes did not live in the mountains, many biolo- gists assumed they were another group of the mixed-breed foxes that are widespread throughout the California valleys. They’d been present since at least the late 1800s, but no one knew for sure whether they were native or introduced. Through DNA analysis, the team, this time led by Ben Sacks, discovered that Sacramento Valley foxes are not only native—they are closely related to the Sierra Nevada popula- tion—but represent a new subspecies of red fox. The team named it Vulpes vulpes patwin, after a Native American group that once inhabited the valley. This finding highlights the practical prom- ise of this sort of research. If managers can In 2010, a remote-camera survey captured this image of a fox on the Humboldt-Toiyabe National Forest, positively identify red foxes as native or non- California. native, they can target conservation efforts to the appropriate gene pools. And, as they learn joined the native foxes, but the genetic analy- in ways that the lowland, mixed-breed foxes more about the influence of genes on envi- sis found no mixing. are not. If so, some of these adaptations may ronmental adaptations, they will have a basis be detectable through genetic analysis. Similarly, says Aubry, lowland fox popula- for identifying the key ecological factors that For example, Sacks’s team in their study of limit survival in a given population. tions on the Olympic Peninsula—all intro- duced since European settlement—have not the Sacramento Valley red fox population For example, the research sheds light on a colonized the high Olympics, where native red speculated that the mountain foxes’ cold toler- question long pondered by Aubry: Why don’t foxes do not occur. “There are no obvious bar- ance may be keyed to certain patterns in their mountain and lowland foxes interbreed? In riers to colonization—in fact, there’s a paved mitochondrial DNA. Mitochondria—energy- his doctoral work on Cascade red foxes in road right up to the alpine zone on the north generating bodies within the cells of most the 1980s, he’d observed that thick west-side side of the peninsula,” he says. “If introduced organisms—are known to be involved in forests and sparse east-side sagebrush deserts red foxes were capable of colonizing those metabolism. If such environmental preferenc- seemed to act as barriers to up- or downhill high-elevation areas, they’d have gotten up es can be teased out of a fox’s genes, further migration. Later, Perrine noted that there had there.” research could yield insights into important been fur farms within the range of the Sierra ecological relationships, including the critical Nevada foxes, and escapees could easily have The mountain-dwelling foxes, he surmises, thresholds that limit survival. must be adapted to their harsh environments

4 A HOPEFUL REMNANT LAND MANAGEMENT IMPLICATIONS ntil the last few decades, the most recent physical evidence of red foxes in the high Sierras was a museum • Montane red foxes have suffered range losses during the past century from unknown U causes. Global climate change poses a potentially serious threat to their persistence in specimen collected in 1941. Accordingly, the Sierra Nevada red fox was listed as a threat- the habitat islands they occupy in the high mountains. Genetic research provides the ened species in California in 1980. However, means for determining the current distribution and abundance of native montane foxes during the winter of 1990–91, a photograph and for evaluating their conservation needs more effectively. of a red fox was taken near Tioga Pass, just outside , raising scien- • The current study provides the foundation for further research on the genetic character- tists’ hopes. istics of North American red fox populations. This unfolding information will be essen- tial for identifying potentially threatened native populations and will help managers In the intervening decades, biologists have understand the habitat factors that may be critical for their survival. used remotely triggered cameras, live traps, and other techniques to survey for red foxes • The most urgent needs for the management and conservation of Sierra Nevada red and other high-elevation mammals throughout foxes and other potentially imperiled populations are new field and laboratory studies the Sierra Nevada. John Perrine had conduct- designed to provide baseline information on their distribution and status, physiology, ed a field study of the red foxes near Lassen population dynamics, and habitat relations. Peak during the late 1990s and early 2000s, but none had been found anywhere south of there—the Tioga Pass photo remained the last Mark Statham (now at U.C. Davis) extracted documented record from the southern Sierras. DNA from the saliva and confirmed that the Scientists feared the southerly foxes might be genetic signature matched that of the histori- gone forever. cal Sierra Nevada red foxes. KirbyCalhoun Then in August of 2010, Forest Service These detections have given scientists hope, biologists Adam Rich and Sherri Lisius were but they also illustrate just how precarious the conducting remote-camera surveys in the foxes’ situation is. Montane foxes are unique, Humboldt-Toiyabe National Forest, baiting their Aubry says, not only in their genetic makeup, cameras with chicken parts stuffed into a but in their adaptation to a cold, isolated, and sock. One of their cameras snapped a picture shrinking environment. “Native red foxes of a red fox as it jumped to grab the food. are an essential component of those montane Later in the fall, two more red foxes were ecosystems,” he says, “and to lose them would photographed on the Stanislaus National be to lose an important piece of the system. I Forest a few miles away. hope our work makes people aware of these unique animals and of the disjunct and pre- Wildlife biologists throughout California were Researchers extracted DNA from saliva left behind carious of their primary habitat. They buzzing: maybe the southern Sierra Nevada on the bait sock (tied around tree) and determined have been evolving in North America for hun- red foxes weren’t completely gone after all. that Sierra Nevada red foxes still lived in the area. dreds of thousands of years, and are a unique Ben Sacks was elated when the bait sock was form of the red fox that occurs nowhere else recovered with fox saliva on it. Sacks and in the world.”

FOR FURTHER READING Sacks, B.N.; Moore, M.; Statham, M.J.; Sacks, B.N.; Wittmer, H.U.; Statham, M.J. Wittmer, H.U. 2011. A restricted hybrid 2010. The native Sacramento Valley red Aubry, K.B.; Statham, M.J.; Sacks, B.N.; zone between native and introduced red fox. Report to the California Department Perrine, J.D.; Wisely, S.M. 2009. fox (Vulpes vulpes) populations suggests of Fish and , May 30, 2010. 49 p. Phylogeography of the North American red reproductive barriers and competitive fox: vicariance in forest refu- exclusion. Molecular Ecology. 20: 326–341. gia. Molecular Ecology. 18: 2668–2686. Sacks, B.N.; Statham, M.J.; Perrine, J.D.; WRITER’S PROFILE Perrine, J.D.; Campbell, L.A.; Green, G.A. Wisely, S.M.; Aubry, K.B. 2010. North Gail Wells is a science writer based in 2010. Sierra Nevada red fox (Vulpes vulpes American montane red foxes: expan- Corvallis, Oregon. She is the author of The necator): a conservation assessment; final sion, fragmentation, and the origin of the Tillamook: A Created Forest Comes of Age report R5-FR-010. U.S. Department of Sacramento Valley red fox. Conservation (2nd ed. 2004) and coauthor of Lewis and Agriculture, Forest Service. 42 p. Genetics. 11: 1523–1539. Clark Meet Oregon’s Forests: Lessons From http://nrm.dfg.ca.gov/FileHandler. Dynamic Nature (2004). ashx?DocumentID=23994. (March 10, 2011).

5 PRSRT STD US POSTAGE PAID PORTLAND OR FINDINGS PERMIT N0 G-40 U.S. Department of Agriculture Pacific Northwest Research Station 333 SW First Avenue P.O. Box 3890 Portland, OR 97208-3890 Official Business Penalty for Private Use, $300

scientist profile KEITH AUBRY is a re- Aubry may be contacted at: COOPERATORS search wildlife biologist USDA Forest Service John D. Perrine, California Polytechnic State with the USDA Forest Pacific Northwest Research Station University Service, Pacific North- Forestry Sciences Laboratory west Research Station in 3625 93rd Ave. SW Benjamin N. Sacks, University of California Olympia, Washington. He Olympia, WA 98512 at Davis has been studying the ecol- (360) 753-7685 ogy of terrestrial wildlife E-mail: [email protected] Mark J. Statham, University of California at in the Pacific Northwest Davis for more than 25 years. Recent and current Samantha M. Wisely, Kansas State University research activities include field studies of the pileated woodpecker, , Canada , and in the Pacific Northwest; the historical zoogeography and genetic affinities of the fisher, wolverine, and red fox in North America; and the application of genetic infor- mation to wildlife research and conservation.

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