With their distinctive curved, slender beaks and clear, whistling alarm call, Long-billed Curlews are popular among birdwatchers during spring and early summer in Idaho. The largest shorebird in the United States, curlews migrate from coastal wintering grounds to nest and hatch their young among the state's short grasses. And though they spend most of their time methodically foraging for food on the ground, they aren’t shy about taking wing to fend off threats.
“I love seeing how aggressive they are, to defend their nests with their chicks against predators—dive-bombing a badger, or even hitting a Golden Eagle or raven or Red-tailed Hawk that is coming through their territory,” says Jay Carlisle, research director of the Intermountain Bird Observatory at Boise State University. “They will get up and above a raptor and steeply dive, and their flight can be almost falcon-like. It’s awe-inspiring.”
But curlews’ spectacular aerial displays are growing rarer in southwest Idaho, once the densest nesting ground for Long-billed Curlews in the United States. Surveys suggest overall Long-billed Curlew numbers have dropped by 92 percent in the region over the last 40 years. And based on available data, the biggest threat is poaching: recreational shooters who are illegally killing the birds at an alarming rate, particularly around Boise and the surrounding Treasure Valley region.
Since 2013, Carlisle has equipped 70 curlews across the Northern Rockies and British Columbia with satellite transmitters to discover what’s behind the species’ decline, including 16 curlews on public lands in southwest Idaho overseen by the Bureau of Land Management (BLM). He and his research team soon learned that, in Idaho, a static transmitter signal often means a poached bird. Just three weeks into the program, a tracked bird was illegally shot and killed. Overall, seven of the 16 satellite-tagged curlews have been found dead, shot by poachers—nearly half of the representative sample.
Those seven birds are likely a small taste of the full extent of the poaching. Most poached birds are never reported as such; to your average observer, a poached curlew would look like any other dead curlew. And Carlisle's team regularly stumbles upon other poached birds in the field beyond those in their study. On June 1, they found an untagged mother shot through her wing and body, the third confirmed poaching death in 2018.
“It’s hard to ignore,” Carlisle says. While researchers are still studying their data, Carlisle says he “can’t imagine [poaching] is not the number-one cause.”
Scientists first documented Idaho’s significant curlew populations in the 1970s, identifying roughly 1,000 nesting pairs across 66,000 acres of BLM public lands. Recognized as the densest nesting grounds for the birds in North America, the core area was eventually designated the Long-Billed Curlew Area of Critical Environmental Concern (ACEC) and managed by BLM to limit human disturbances to nesting birds.
In recent years, urban development in and around Boise has presented new threats. Suburban homes have paved over irrigated farmlands that served as important feeding grounds for curlews. And population growth—Boise is now the fastest-growing area in the country, according to Forbes—has meant a rise in visitors to curlew habitat on BLM lands, including the Curlew ACEC and the Morley Nelson Snake River Birds of Prey National Conservation Area.
“There has been a huge increase in recreational pressures,” says BLM’s Matt McCoy, particularly target and recreational shooting and off-highway vehicle use. Shooters flock to BLM lands where there’s space for target shooting and it’s legal to shoot and kill ground squirrels and prairie dogs, which many view as varmints.
Curlews, on the other hand, are not game birds and are protected under the federal Migratory Bird Treaty Act. But while most shooting enthusiasts are responsible and law-abiding, those who aren’t can find illicit “easy targets” in curlews nesting on the ground or boldly diving to defend their broods, McCoy says.
Brian Flatter, a conservation officer with Idaho Department of Fish and Game, says shooting incidents of curlews, Burrowing Owls, and raptors are all on the rise in addition to other illegal shooting. “We’re documenting a lot of violations, but it’s always after the fact,” Flatter says. While Carlisle’s study with satellite-tagged birds has a small sample size, it’s still better than the data officials have on other species at risk of poaching.
“[Carlisle’s] research has exposed the indiscriminate killing of curlews, but there are many other species on their study area, throughout Idaho, and across the West that are illegally shot,” says Sean Finn, past president and current board member of Golden Eagle Audubon Society in Boise. “In that sense, Long-billed Curlews are a 'poster child' of a broader problem that can be difficult and expensive to quantify.”
The fallout is particularly severe for curlews, Carlisle says. The species is long-lived, but the birds reproduce just once a year, have relatively small clutch sizes of 3-5 eggs, and must fend off predators for more than a month until their young can take flight. Those factors account for curlews’ aggressive and showy defense behavior—which is no match for a rifle or shotgun. They also mean that poaching of breeding-age birds could account for the cascading drop in curlew numbers in southwestern Idaho.
Through monitoring, Carlisle and others are examining how threats besides poaching—such as declines in wintering habitat in California’s Central Valley—also contribute to regional curlew losses. Overall, nesting populations elsewhere across the Northern Rockies are mostly holding steady, and not a single satellite-tagged bird from another region has been poached. But that doesn’t mean losses in southwestern Idaho are no big deal; conservation managers note that the loss of a major population weakens the entire species.
“When you have widely distributed birds, that is how they make it,” Flatter says. “You need these populations to provide the birds an ability to absorb local impacts, whether it’s drought, fire, disease, or illegal shooting.”
In response, conservation partners are pushing a mix of education and enforcement to reverse the trends. The Intermountain Bird Observatory has launched a Curlews in the Classroom school program to teach students about curlews, the observatory’s research, and the birds’ local decline. Carlisle says the program aims to build pride towards Idaho’s curlew populations and raise awareness of the impacts of illegal shooting. The observatory has begun extending its outreach to hunter-education courses this year, too.
Catching poachers, however, is notoriously difficult, and even more so across vast public lands: BLM’s Boise District, where McCoy works, encompasses more than 4 million acres, yet only three full-time federal law-enforcement officers patrol the region. Idaho Fish and Game is also stepping up enforcement of shooting rules and poaching on public lands, even placing decoys on nests, but has yet to catch any scofflaws.
“It all points toward a big problem, if we don’t act quickly,” McCoy says. “We’re looking at an area that went from the highest density [of curlews] in the western United States down to a [nearly] 95 percent reduction. That’s a key indication we’re not doing a good job managing the lands out there, and if we continue on this track we’re going to lose the birds in southwest Idaho.”
It’s another troubling sign for the world’s curlews. Several species are declining or endangered, but so far the Long-billed Curlew population has held steady. If such wanton killing continues, though, it could go the way of the Eskimo Curlew, once among the most common shorebirds in North America and now functionally extinct.
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