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Home , Moose, Rocky Mountain Front

SOLVING ’S MYSTERIES FWP researchers search for answers to help conserve these popular big in the face of rising temperatures, shrinking habitat, and more predators. BY TOM DICKSON

DONALD M. JONES

12 | SEPTEMBER–OCTOBER 2019 | FWP.MT.GOV/MTOUTDOORS MONTANA OUTDOORS | 13 each year, compared to 25,000 and 95,000 mule and white-tailed deer. Moose managers have long been frus- In winter, the Big Hole valley looks like a trated by the scant information, especially re- garding population sizes and trends, which vast white lake lapping against the Pioneer help them determine harvest quotas. “It’s a major dilemma,” says Ryan Rauscher, Mountains to the east and the Beaverhead FWP wildlife biologist in Conrad, whose Mountains to the west. The 15-mile-wide expanse of work area includes moose range along the . “If a moose popula- snow sits atop a mix of sagebrush prairie, pasture, tion is trending down and we overharvest by hayfields, and swamp. Within this broad valley issuing too many licenses, we could set re- covery back for years.” and surrounding forests resides one of the state’s At the same time, if managers don’t know largest moose populations. that a population is growing and could sustain additional harvest, they must be On a frigid February morning, the tem- and possessing a noble snout, moose are cautious and issue fewer licenses than if they perature hovering around -20 F., Montana one of ’s most popular had more accurate data. “That means Fish, Wildlife & Parks wildlife research biol- wildlife . Tourist shops sell sweat- denying some hunters a hunt of a lifetime,” ogist Nick DeCesare and I are driving across shirts, mugs, and postcards adorned with says Rauscher. the valley near Wisdom searching for a cow images of this largest member of the deer The need for information grew in the moose he has radio-collared. Two miles out family. “Landowners, hunters, residents, mid-1990s, as hunters and others started of town, he parks his pickup along a frozen nonresidents—you name it—I’ve found that reporting fewer moose in parts of western county road. After picking up a strong signal almost everyone loves moose,” says Jesse Montana. Hunter success rates began with his radio receiver, we wade through Newby, an FWP wildlife research technician declining too, as did annual harvest. The hot, knee-deep snow in pursuit. working with DeCesare. dry years of the early 2000s raised “There,” DeCesare says a few minutes Despite the popularity of Alces alces, Mon- concerns further. Moose require cool, wet later, pointing to two distant dark shapes. A tana wildlife managers lack information about climates and can overheat in summer cow moose sporting a bright white collar the species’ diet, movements, pregnancy rates, temperatures above 60 degrees. Large and her pause against a stand of wil- and other basic “vital rates.” FWP lacked that need Alaskan weather were lows. Then they amble off, long legs carrying funds to study a species that generates rela- enduring Arizona-like conditions. them easily through the deep drifts. Trudg- tively little hunting license revenue. Only , , , ing after the pair, DeCesare gathers a hand- about 300 moose are harvested in Montana Wyo- ming, and other provinces and states ful of the cow’s fresh thumb-sized droppings to be tested for progesterone, indicating pregnancy. DeCesare, who earned his doctorate in wildlife biology at the University of Mon- tana, makes his way back to his truck. He mentions that he’s been following this par- ticular moose for six years, watching her raise to young adulthood as part of a study he’s doing with other research scien- tists. “It’s great getting all this broad popu-

lation-wide data that will eventually be S; DONALD M. JONES used to manage moose,” he says. “But it’s also pretty neat that we get to intimately OUTDOOR OFFICE know these individual moose year after FWP wildlife research biologist Nick DeCesare, who runs the 10- MONTANA OUTDOOR MONTANA year. They’re such cool animals.” year moose study, logs data after gathering droppings from a cow moose in the Big Hole WELL-LOVED valley. Chemical analysis will determine if Few would disagree. Nearly as large as a she’s pregnant. Later surveys will monitor horse, graceful and stately in movement, whether the cow gives birth, and how well the calf (or calves, if twins) survives (right). LEFT TO RIGHT: TOM DICKSON/ TOM RIGHT: LEFT TO

14 | SEPTEMBER–OCTOBER 2019 | FWP.MT.GOV/MTOUTDOORS MONTANA OUTDOORS | 15 FACTORS AFFECTING also were reporting moose declines (though if so, whether to single calves or twins. The clude Safari Club International, The Nature VARIABLES MOOSE POPULATIONS in some parts of , including researchers check a few months later to Conservancy, and dozens of local landown- northeastern Montana, numbers were in- monitor calf survival, then fly again the fol- ers, as well as other wildlife agencies in the INFLUENCES FACTORS AFFECTING POPULATION POPULATION TREND creasing). A population in , one of lowing March to see if the young are still United States and studying moose the largest in the lower 48 states, crashed alive and thus have been “recruited” into and sharing results. Successful moose HUNTER HARVEST NUTRITIONAL CONDITION from roughly 4,000 in the mid-1980s to the population. “The first year is critical,” hunters also assist by sending in blood sam- almost zero in the mid-2000s. “We started Newby says. “That’s when calves are most ples and measuring rump to provide addi- PREDATION to wonder: Is there a continent-wide trend vulnerable to predators, disease, and mal- tional data. ADULT FEMALE SURVIVAL that Montana is a part of?” says Justin Gude, nutrition. If they make it through their first FORAGE & HABITAT or head of FWP’s wildlife research program. MAJOR FINDINGS ADULT FEMALE FECUNDITY Meanwhile, and other large carni- Now on year seven of the study, researchers PARASITES & DISEASE vore numbers were increasing. And logging, have already learned much about Montana’s which opens forests to sunlight that gener- moose. Perhaps most significantly, none of HEAT STRESS & SNOW CALF SURVIVAL ates more and other shrubs that the three studied populations appears in dire moose prefer, had declined for decades. straits. “We didn’t know what we’d find, so The main factors that determine whether a moose population increases or decreases: survival of adult females (which produce young and thus drive a population), Were these factors driving moose numbers that’s definitely good news,” DeCesare says. cow moose pregnancy rates (fecundity), and calf survival. Driving fecundity and calf survival is the animals’ health (nutritional condition), which is influenced by down? What about parasites—winter ticks, The main discovery in the Big Hole is that habitat, disease, and stress; other influences are hunter harvest and predation. FWP researchers are monitoring and measuring all these influences and factors. brain worms, arterial worms, and many adult moose are being killed by three- flukes—to which moose are particularly vul- inch-long parasites transmitted from horse- nerable? “With so many possible factors, it flies. These arterial ormsw congregate in the 1.00 was impossible to figure out the right course arteries at the base of the ’s head and Population growth rates: 2013–2018 +4% +8% +12% +16% +20% of action for managing moose,” says Gude. apparently restrict blood flow to the brain. This chart shows the two main factors affecting “We needed answers.” Researchers found Big Hole pregnancy moose populations: cow survival rates and rates 0.95 -4% MOOSE MONITORING Nick DeCesare with rates and calf survival comparable to the of calf recruitment (survival to age one). The dark +3% a cow moose tranquilized from a dart fired line in the middle indicates a stable population. 10 YEARS, 3 AREAS other areas, but that hasn’t fully offset the -8% STABLE POPULATION +11% from a helicopter. After drawing blood Populations above the line are growing, and the one 0.90 Since 2013, FWP research scientists have decline in adult cow numbers. The result has samples and taking body measurements, below the line is shrinking slightly. Note that even worked to answer these and other moose he attaches a collar fitted with a radio been a slight annual population decline of though calf survival in the Cabinet-Salish is relatively -12% management questions with an unprece- transmitter. Transmitters on 162 moose 3 percent over the past six years. “The two low, the population is still increasing at 3% per year .085 -3% dented 10-year study. Its two primary goals tracked in the three study areas (below) drivers of moose populations are adult due to the high cow survival. allow scientists to locate individual animals -16% are (1) understand the relative importance of female mortality and calf survival,” Newby On the Front, both rates are and see which habitats they use and how high, leading to an 11% adult cow survival, cow pregnancy, calf sur- explains. “And of the two, cow mortality is 0.80 well they survive from year to year. annual population growth. survival female Adult -20% vival, and other factors driving moose popu- the biggest factor. That’s why the Big Hole lation ups and downs; and (2) find a cost- population is struggling a bit.” n Cabinet-Salish Moose Population Ecology Study Areas 0.75 effective way to monitor moose numbers in Researchers’ most important finding in n Big Hole Valley 0.00 0.10 0.20 0.30 .040 0.50 the future. Cabinet-Salish Mountains the Cabinet-Salish study area is the popula- n Rocky Mountain Front The study focuses on moose in three tion’s poor moose calf survival—the lowest by Calves recruited per adult female widely different areas: the upper Big Hole val- Rocky Mountain Front far of the three areas. “It’s what you’d expect ley and surrounding mountains, the east Cab- from a region with a lot of large carnivores,” inet and Salish Mountains near Libby, and the DeCesare says. Researchers set up trail cam- Causes of female What kills* adult cow moose? Rocky Mountain Front in western Teton and Big Hole Valley eras confirming that the moose study area is northern Lewis and Clark Counties. rich in predators, including mountain lions, moose mortality: Predation (11) During the first six years of the project, black , and . 2013–2018* n n (1) 162 moose have been captured with nets or Fortunately, the Cabinet-Salish has high Despite widespread speculation n Lion (1) tranquilizer darts. Scientists check each an- winter, they stand a good chance of living a adult cow survival, which more than offsets that adult moose are being killed Health related (34) n Wolf (9) imal’s fat content, age (by examining teeth), long time.” the calf loss to predators and has accounted by wolves and other carnivores, the study shows that the main Researchers found a n (4) other vitals, and tick numbers before fitting Researchers also monitor adult cow sur- for a modest annual population growth of culprits are health related. FWP wide range of health- n Vehicle related causes including it with a large white collar carrying a radio vival, analyzing fecal pellets to learn which 3 percent. researchers had suspected winter collision (2) old age, disease, parasites, n Poaching (1) transmitter, which emits a unique fre- plants the moose eat. By using ultrasound The story along the Front is a strong ticks, which have devastated and injuries. In the Big Hole, n Hunting (1) quency. In winter, they determine preg- equipment to measure body fat in captured 11 percent annual population increase. The populations in northeastern the major factor was nancy rates by analyzing fecal pellets. In cows and monitoring the percentage that main driver, Newby says, is the relatively high states. But it turns out that the arterial worms. n Unknown (7) major cause of mortality, espe- spring, they fly in planesor helicopters to give birth to twins, they can determine the number of calves that cows churn out each cially in the Big Hole study area, n Accident (1) see if pregnant cows have given birth and, nutritional quality of habitat. year. Though pregnancy rates in all three is arterial worms, which congre- gate in a moose’s neck and FWP isn’t pulling off the moose popula- study areas are similar, moose on the Front * Numbers from the 57 adult female moose Tom Dickson is editor of restrict blood flow to the brain. Montana Outdoors. tion ecology study on its own. Partners in- are fatter, become pregnant at an earlier age, FWP MONTANA BY PHOTOS DURAN; LUKE BY INFOGRAPHICS FWP: RIGHT: MONTANA LEFT: in the study that have died so far.

16 | SEPTEMBER–OCTOBER 2019 | FWP.MT.GOV/MTOUTDOORS MONTANA OUTDOORS | 17 produce more twins, and see higher calf sur- Looking back, the moose researchers edge in more ways than one. FWP is already weighs 750 pounds and stands five feet at vival. “It all seems to be related to nutrition, compared the aerial survey results to hunter saving money by no longer conducting ex- the shoulder would be easy to see, especially that the habitat is super conducive to moose harvest data. Did hunter harvest increase in pensive helicopter flights in many areas. from a helicopter. But along Dupuyer Creek, growth,” says Newby. years when biologists spotted more moose But with most aerial surveys no longer a a shrub-shrouded stream that spills out be- from the air the previous winter? That would smart option, how could managers monitor tween towering granite reefs along the MONITORING POPULATIONS indicate a strong correlation, and show that moose populations. The researchers had an Rocky Mountain Front, Newby and FWP When they aren’t outside tracking moose, the two monitoring methods might be valid idea: What about asking hunters if they saw pilot Rob Cherot struggle to spot a moose DeCesare and Newby sit at computers try- ways to count moose. Too often, however, moose during the season? Not just the 350 they know is directly below. ing to find a way to monitor moose popula- the two didn’t line up. “The lack of a strong or so moose hunters, but also the 160,000 For years Newby has been tracking this tions statewide. correlation means we don’t know which one deer and elk hunters who put in a combined and other cows, watching them grow fat and For decades, FWP moose managers flew to trust, and based on our previous concerns, 2 million days afield each year. “That’s a lot fertile in the lush shrub forest habitat. Today aerial surveys in some hunting districts, but we don’t trust either one,” says Gude, the re- of eyeballs,” says DeCesare. “If the sightings he’s checking to see how well their calves are they wondered about accuracy. Like wolves, search bureau chief. That’s valuable knowl- start corroborating each other, after a while faring. Though aerial surveys aren’t effective moose are difficult to spot in the dense forests you have a real high confidence level of HOW RESEARCH PAYS OFF Biologists hope the 10-year moose population ecology study will for determining moose population estimates, where they often live. Unlike deer and elk, moose distribution and population trend.” provide information to help them offer as many hunt-of-a-lifetime opportunities as possible while a helicopter is still the best way to locate in- which congregate in visible herds, moose are Each winter for several years, FWP ensuring that populations are not overharvested and remain healthy. dividual radio-collared animals. mostly solitary, making them especially phone surveyors have asked hunters if, As the radio receiver beeps louder, indi- tough to spot, even from the air. Unstable and where, and when they saw moose. Scientists ologists have long believed. Hunters in par- those in the other study areas?” cating the moose is even closer, Cherot S; DENVER BRYAN rapidly changing weather in moose range are now using statistical analysis and com- ticular want to know, because it affects how Rauscher, the Conrad-area biologist, banks the chopper and makes another pass also meant surveys were inconsistent during puter modeling to translate the information record-keeping organizations like the Boone hopes the researchers can help him and over a dense stand. Nothing. Then, as widely varying times of the year, rendering into moose populations and population & Crockett Club score moose . other managers track cow and calf survival he circles once again, a large near-black

results only somewhat useful. trends. “Because it’s so cost-effective, we OUTDOOR MONTANA This past summer, researchers and biol- rates after the study ends. “This study is too animal emerges from the pale green foliage In most moose areas, FWP relied on hope this is the answer,” says Gude. “But we ogists have been meeting to decide which expensive and intensive to continue perpet- followed by two smaller red-brown shapes. hunter harvest data, which, when not still need to finish the modeling and vet it other aspects of moose population ecology ually,” he says. “Is there some other way we “There she is, with her twins,” Newby says. backed up by other survey methods, can be with local wildlife managers to see if they the study should consider. “Should we can gather the data we need to manage It’s an encouraging sign during what has even less helpful in monitoring population find the information valuable for setting focus on learning more about what’s killing moose in the future?” been a puzzling summer. After years of trends. “Let’s say you had a hunter success moose seasons.” calves in northwestern Montana?” says high calf survival along the Front, fewer rate of 90 percent one year and 60 percent DeCesare. “Should we spend more time “THERE SHE IS” young moose have been surviving in 2019. the next,” says Vanna Boccadori, an FWP ANSWERS DOWN THE ROAD studying how arterial worms are transmit- Like DeCesare, Newby wants to supply “We don’t really know what’s changed,” wildlife biologist in Butte whose work area Over the next few years, researchers will ted via horseflies to Big Hole moose— wildlife managers with key information they Newby says. covers the Big Hole. “Did that reflect a de- keep monitoring the collared moose and whether from , elk, or some other can use for decades down the road. On this Along with everything else about this EYEBALL BREAK crease in the moose population, or did it Wildlife technician Jesse their young. They’ll also continue studying host? Should we put our resources into un- late June morning, however, he’s simply beloved species that he and other researchers Newby takes a breather after a morning of just mean that hunting conditions were the genetics of Montana’s Shiras moose to derstanding nutritional and habitat differ- hoping to locate one elusive cow moose. are working to better understand, he’ll have monitoring moose along the Front in July.

particularly bad that second year?” see if it is indeed a distinct subspecies, as bi- DICKSON/ TOM LEE VARNADO; JESSE LEFT: BELOW FROM CLOCKWISE ences separating the Front moose from You’d think a large, dark animal that three more years to find out.

Other moose study findings

AFTER STUDYING COW AND CALF MOOSE in three areas for more than During one winter in the Cabinet-Salish study area, two cows crossed found that 60 percent of mortality is from disease and parasites, espe- u Parasites: In addition to the arterial worms found mainly in Big Hole 6 years of a 10-year study, here’s some of what researchers have learned: the Cabinet Mountain Continental Divide. “Those two are great examples cially in the Big Hole,” says FWP research biologist Nick DeCesare. moose, researchers looked at winter ticks. Winter ticks are common on of how we’re seeing many moose living at “Predators account for less than 20 percent.” moose and, in small numbers, cause no problems. But heavy infestations u Moose age and size: Cows ranged from much higher elevations than we’d thought, u Nutrition: In the Cabinet-Salish study area, moose mainly ate shrubs, of 50,000 or more on one animal result in considerable blood loss. During 1 to 16 years old, averaging 6 years, weighed and how they are traveling through snow with some conifers in the winter. In the Big Hole, their winter diet con- winter, the loss leads to depleted fat and eventually muscle reserves. In 650 to 800 pounds, and ranged in length to get there,” says Tonya Chilton-Radandt, sisted of roughly half shrubs and half grass and sedges (from haystacks), other northeastern states, winter ticks are responsible for major moose from 8 to 9 feet long. FWP wildlife biologist in Libby. and shrubs entirely in the summer. On the Front, moose ate only shrubs population declines. u Movement: Most moose stayed within u Adult mortality: Of the 57 collared in the winter and mostly shrubs in the summer. On moose in the three Montana study areas, researchers found winter areas of 10 square miles or less, but some cow moose that have died so far, 34 per- u Pregnancy: All three populations had roughly the same pregnancy tick numbers ranging from just a few hundred to 8,000 per animal. The ranged widely. One cow from the Front ished from arterial worms and other health- rates. The more rump fat that cows had—a reflection of nutrition—the highest tick loads were along the Front. Yet that’s also where moose had traveled as far east as Havre. Another related causes, 11 from predators (wolves, more likely they were to get pregnant. the highest pregnancy rates, the highest rates of twins, and the greatest roamed well into , Canada. “Young grizzly bears, mountain lions), 4 from hu- u Recruitment: By far, the highest “recruitment”—the rate of calves that population increase. “So it doesn’t look like ticks are limiting Montana males are known to range, but we were sur- mans (poaching, vehicle accident, hunting), are born and survive one year—was on the Front, likely due to more nu- moose fecundity or survival,” says DeCesare. prised to see several females making such 1 from a natural accident, and 7 from un- tritional habitat and less predation. Next was the Big Hole population, Researchers also found that brainworms (carried by white-tailed long journeys,” says FWP research technician known causes. “People assume that large and in last place were the Cabinet-Salish calves, likely because of high deer) are not killing Montana moose as they are in states to the east, Jesse Newby. carnivores kill a lot of adult moose, but we numbers of large carnivores in the area. especially Minnesota. n

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