Wildlife technician Jordan Hazan records data in a lab from a male barred owl he shot earlier in the night, Oct. 24, 2018, in Corvallis, Ore.
| Photo Credit: AP

U.S. wildlife officials beginning next year will drastically scale up efforts to kill invasive barred owls that are crowding out imperiled native owls from West Coast forests, under a plan finalised Wednesday that faces challenges from barred owls returning after they’ve already been removed.

Trained shooters will target barred owls over 30 years across a maximum of about 23,000 square miles (60,000 square kilometers) in California, Oregon and Washington. The U.S. Fish and Wildlife Service goal is to kill up to 452,000 barred owls and halt the decline of competing northern spotted owls and California spotted owl s.

Killing one bird species to save others has divided wildlife advocates and is reminiscent of past government efforts to save West Coast salmon by killing sea lions and cormorants, and to preserve warblers by killing cowbirds that lay eggs in warbler nests. The barred owl removals would be among the largest such effort to date involving birds of prey, researchers and wildlife advocates said.

Native to eastern North America, barred owls started appearing in the Pacific Northwest in the 1970s. They’ve quickly displaced many spotted owls, which are smaller birds that need larger territories. An estimated 100,000 barred owls now live within a range that contains only about 7,100 spotted owls, according to federal officials.

The newcomers’ arrival also threatens to decimate frog and salamander species that barred owls prey on.

“It’s not just one owl versus one owl,” said David Wiens, a U.S. Geological Survey scientist who led a barred owl removal study that ended in 2020. “Because of their predatory behavior, they are basically eating anything in the forest and this includes amphibians, small mammals, other bird species.”

Government officials say 15 years of killing barred owls experimentally, including on Northern California’s Hoopa Valley Indian Reservation, shows the controversial strategy could halt the decline of spotted owls. Yet researchers warn that few spotted owls remain in some areas, and it could take years to turn the tide on the barred owls’ aggressive expansion.

Former Fish and Wildlife Service biologist Kent Livezey said the mass killing of barred owls was ill-advised and could cost hundreds of dollars per bird. Livezey has documented more than 100 bird species that expanded their range in recent years.

“We should let nature take its course,” he wrote in an email. “Birds (and all animals) move. Competitions arise. Should we be stepping in and killing mass numbers of them like this?”

The wildlife service would designate government agencies, landowners, tribes or companies to carry out the killings. Shooters would have to provide documentation of training or experience in owl identification and firearm skills.

“We’re still going to have barred owls in the West. This is really just about trying to prevent the extinction of spotted owls,” said Fish and Wildlife Service Oregon state supervisor Kessina Lee. She declined to give a cost estimate and said that would depend in part on the willingness of other government agencies and land managers to participate.

Northern spotted owls are federally protected as a threatened species. California spotted owls were proposed for federal protections last year. A decision is pending.

Barred owls arrived in the Pacific Northwest via the Great Plains, where trees planted by settlers gave them a foothold, or via Canada’s boreal forests, which became warmer and more hospitable as the climate has changed, researchers say.

Their spread has undermined decades of spotted owl restoration efforts that previously focused on protecting forests where they live. That included logging restrictions under former President Bill Clinton that ignited bitter political fights and temporarily helped slow the spotted owl’s decline.

Wayne Pacelle with the Washington D.C.-based advocacy group Animal Wellness Action said the government’s plan was a distraction from the threats of logging. He said federal officials were misusing the term “invasive species” at a time when animals are migrating to new areas because of global warming and other human-caused changes.

Read | Waking to the call of the wild

“It’s ludicrous to think animals are going to stay in some historical range,” Pacelle said.

Barred owls are highly territorial, which makes killing them relatively straightforward, according to researchers. Shooters use megaphones to broadcast recorded owl calls at night and lure the birds close to roads where they are killed with shotguns.

“The birds will come right in. They’re very focused on this recording,” Wiens said. “If we go into a site and detect a barred owl there, we have over a 95 % chance of removing that barred owl.”

Other potential approaches — including capturing and euthanising barred owls, collecting their eggs to prevent reproduction, or hazing them out of areas with spotted owls — were considered by the wildlife service but rejected as too costly or impractical.

About 4,500 barred owls birds have been killed on the West Coast since 2009 by researchers, according to officials.

That includes more than 800 birds from the Hoopa reservation, said tribal wildlife biologist Mark Higley.

Higley conducts the barred owl removals across 140 square miles (364 square kilometers) primarily by himself, working two or three nights a week from early spring until late fall.

“The problem has been we get like 60 to 100 new barred owls each year,” he said. “Don’t get me wrong; barred owls are magnificent species. I just would really like to go see them where they’re native and not invasive.”

Paris:

Invasive species that wreck crops, ravage forests, spread disease, and upend ecosystems are spreading ever faster across the globe, and humanity has not been able to stem the tide, a major scientific assessment said Monday.

The failure is costing well over $400 billion dollars a year in damages and lost income — the equivalent to the GDP of Denmark or Thailand — and that is likely a “gross underestimation”, according to the intergovernmental science advisory panel for the UN Convention on Biodiversity (IPBES).

From water hyacinth choking Lake Victoria in East Africa, to rats and brown snakes wiping out bird species in the Pacific, to mosquitoes exposing new regions to Zika, yellow fever, dengue and other diseases, the report catalogued more than 37,000 so-called alien species that have taken root — often literally — far from their places of origin.

That number is trending sharply upward, along with the bill for the damage multiplying fourfold per decade, on average, since 1970.

Economic expansion, population increase and climate change “will increase the frequency and extent of biological invasions and the impacts of invasive alien species,” the report concluded.

Only 17 percent of countries have laws or regulations to manage this onslaught, it said.

Whether by accident or on purpose, when non-native species wind up on the other side of the world, humans are to blame.

The spread of species is hard evidence that the rapid expansion of human activity has so radically altered natural systems as to tip the Earth into a new geological epoch, the Anthropocene, scientists say.

Hitchhikers

The hyacinth that at one point covered 90 percent of Lake Victoria — crippling transport, smothering aquatic life, blocking hydroelectric dam intake and breeding mosquitoes — is thought to have been introduced by Belgian colonial officials in Rwanda as an ornamental garden flower before making its way down the Kagera River in the 1980s.

The Florida Everglades is teeming with the destructive offspring of erstwhile pets and house plants, from five-metre (16-foot) Burmese pythons and walking catfish to Old World climbing fern and Brazilian pepper.

In the 19th century English settlers brought rabbits to New Zealand to hunt and for food. When they multiplied like, well, rabbits, officials imported ferocious little carnivores called stoats to reduce their numbers.

But the stoats went after easier prey: dozens of endemic bird species that were soon decimated, from baby Kiwis to wrybills.

New Zealand and Australia — where a similar bad-to-worse saga involving rabbits unfolded — are “case studies” of how not to control one imported pest with another, Elaine Murphy, a scientist at New Zealand’s Department of Conservation, told AFP.

More often, however, invasive species are accidental arrivals, hitching rides in the ballast water of cargo ships, the containers in their holds, or in a tourist’s suitcase.

The Mediterranean Sea is full of non-native fish and plants, such as lionfish and killer alga, that journeyed from the Red Sea through the Suez Canal.

Vulnerable small islands

Murder hornets capable of wiping out entire bee colonies in a single attack are thought to have arrived in the US from Asia as stowaways in freight.

Largely due to huge volumes of trade, Europe and North America have the world’s largest concentrations of invasive species, defined as those that are non-native and cause harm and have relocated due to human activity, the IPBES report shows.

Invasive species are a significant cause in 60 percent of all documented plant or animal extinctions, one of five main drivers along with habitat loss, global warming and pollution, according to the findings.

These drivers interact: climate change has pushed alien species into newly warmed waters or lands where native species are often vulnerable to intruders they have never encountered.

The deadly fire that reduced the Hawaiian town of Lahaina on Maui to ashes last month was fuelled in part by bone-dry grasses — imported decades ago to feed livestock — that has spread across abandoned sugar plantations.

A global treaty to protect biodiversity hammered out in Montreal last December sets a target of reducing the rate at which invasive alien species spread by half by 2030.

The IPBES report lays out general strategies for achieving this goal, but does not assess the chances of it being met.

There are basically three lines of defence, according to the report — prevention, eradication and then, failing that, containment.

Attempts at eradication have generally failed in large bodies of water and open waterways, as well as on large tracts of contiguous land. The places with the highest rate of success in removing unwanted guests — especially rats and other vertebrates — are also the ones that have proved most vulnerable: small islands.

(This story has not been edited by NDTV staff and is auto-generated from a syndicated feed.)