A rare bird and bumblebee fight for survival in Maine

Feb. 18—Maine officials want to add a rare bird and bee to the state's endangered species list: the Saltmarsh sparrow, a secretive little songbird under dire threat from rising seas, and the Ashton's cuckoo, the hive-stealing bumblebee once thought to be locally extinct but which may be mounting a comeback.

Scientists worry the Saltmarsh sparrow could go extinct as soon as 2035, the first U.S. bird casualty of a rising sea. The bird builds a nest, lays its eggs and rears its chicks in between the highest of spring tides, but rising sea levels and more-frequent storm surges are causing widespread nest failures.

"This isn't like the tiger or the panda, some species in trouble in some faraway place," said University of Maine ornithology professor Brian Olsen, who has been studying the species since 2012. "The Saltmarsh sparrow is a U.S. songbird, a Maine songbird. If we don't save it, nobody saves it."

That work should start with the protection and restoration of Maine's saltmarsh habitat, he said. What helps the sparrow will also help other birds, amphibians and fish that nest and forage in the marsh, and the nearby communities that rely on the marsh for flood protection and carbon sequestration.

"It's why some of us consider this species our canary in the coalmine for climate change," Olsen said.

Maine officials are proposing to add four birds, a bat and a beetle to the state's list of threatened species, a step below endangered. And they are seeking approval to remove from the endangered list a turtle and a dragonfly species, one of which is now thought to only roam the state as released pets and the other believed to have never been here at all.

A state listing can help a species in trouble. The Maine Department of Inland Fisheries and Wildlife can tap into new funds for research and conservation projects. It can help protect a species from large-scale development. Public awareness, and voluntary conservation measures, usually go up.

If adopted by state lawmakers, these would be the first changes to the state's endangered list since 2015 and only the sixth round of amendments since it was created in 1984. The state's list currently includes 51 species: 26 endangered and 25 threatened birds, mammals, fish, reptiles and amphibians.

The Legislature's Inland Wetlands and Wildlife Committee unanimously supported the proposed changes last week. The only debate was over the fate of the Eastern box turtle. Turtle fans wanted to keep it on the endangered list, but the committee sided with state scientists who argue there is no locally established breeding population.

State wildlife officials told lawmakers that climate change — which plays a role in the declining numbers of several of this year's candidate species — would likely force Maine to revisit the state list more often than in the past. It is unlikely that lawmakers will have to wait another eight years for the next round of changes.

AT THE MERCY OF THE TIDES

At its current rate of decline — about 9% a year nationally and almost 11% a year in Maine — the Saltmarsh sparrow will be lucky to avoid extirpation, which is another term for local extinction, for another eight years, according to Olsen.

The sparrow has 24 to 26 days to produce chicks that can leave the grassy low-lying nest before the next spring tide comes in and floods it. Rising seas and more-frequent storms can mean they won't have the time to nest, lay their eggs and raise their young before the nest is flooded, the eggs washed away and another generation lost.

Scientists estimate that Maine was home to just 1,620 of these songbirds in its 22,500 acres of saltmarsh in 2012. If the 10.6% annual decline held, that would mean only 475 Saltmarsh sparrows remain. Recent tide cycles may have eased the flooding and slowed the population's freefall, Olsen said — for now. But those cycles can shift and work against the sparrow, too.

"Saltmarsh sparrows are in trouble in Maine," Olsen said. "While they are declining very rapidly across the entire Northeast, their entire breeding range, it's happening faster in New England. Our saltmarshes are sinking, they're flooding, and they're taking the Saltmarsh sparrow down with them."

They now number about 60,000 throughout their range, which stretches from the Florida Gulf Coast to Thomaston, Maine, although the population is difficult to estimate because the sparrows are not always easy to find as they dart around the tall grasses of the saltmarsh, rarely flying unless they must.

There is hope in the saltmarsh restoration work being done by Rachel Carson National Wildlife Reserve and Ducks Unlimited. They are learning how to use old salt hay farming methods to draw water pooling on top of the marsh away, and are using sediment from dredging projects to elevate nesting areas.

A BUMBLEBEE REAPPEARS

Not much was known about Maine's bumblebee population back in the 2000s, when U.S. bumblebees fell into decline because of a lethal mix of pesticide use, habitat loss, climate change and the introduction of non-native pathogens carried by commercial bee colonies trucked across the country to pollinate farms.

Historical records suggest that Maine had 17 native bumblebees. Its rarest? The Ashton's cuckoo. Like the cuckoo bird, this bumblebee can't rear its own young; instead, it lays its eggs among a host species' hive and forces the workers to raise them. Without a host, the Ashton is doomed.

In Maine, the Ashton relied on two host species, the rusty-patched and yellow-banded bumbles, both of which suffered significant declines. Scientists think the rusty-patched bumble is locally extinct, and they thought the same of the Ashton until 2017.

That is when a citizen science project called the Maine Bumble Bee Atlas, launched by the Maine Inland Fisheries and Wildlife Department with help from the University of Maine in response to the declines of the 2000s, delivered a miracle: a single Ashton's cuckoo found in northeastern Maine.

"It was the most exciting news," said Beth Swartz, a department wildlife biologist and co-founder of the Maine Bumble Bee Atlas. "It can be depressing dealing with endangered and threatened species, but this gives you a little bit of hope. That it was found by a volunteer made it even more special."

The atlas project relied on a handful of professional scientists and over 200 trained volunteers to fan out across the state and collect data on Maine bumblebees. From 2015 through 2020, participants collected 27,000 photographs or pinned specimens that were cataloged by a professional taxonomist.

"The state doesn't have the resources to go out and do statewide surveys, so we created our own team to do it," Swartz said. "As a result of that, we now know a whole lot more about bumblebee fauna. We know we didn't lose Ashton's cuckoo. It was still here, we just had to keep looking."

The Ashton itself — the crown jewel of the atlas finds — sat pinned in a box for at least a year while a state-hired taxonomist confirmed the identity and logged every bee specimen, Swartz said. They are very hard to identify. The volunteer didn't even realize what they'd found. He found three more in 2018 and 2019.

Swartz said it is likely the Ashton has survived because the yellow-banded bumblebee is in recovery and can be found across most of Maine, albeit in small numbers. The rebound of one of its host species could open the door to an Ashton recovery, too — if the species isn't too far gone, Swartz said.

Last year, Swartz traveled to Van Buren, the small town on the Canadian border where the volunteer had found the Ashton before, in hopes of a repeat appearance, but they had no such luck. Swartz is not giving up, though. An Ashton's colony has been confirmed across the St. John River in New Brunswick.

"We're at the very beginning of our work," Swartz said. "We need more data. We need to keep looking."

MORE CLIMATE IMPACTS

The state is recommending the Margined tiger beetle as another species dependent on the success of the disappearing saltmarsh for its survival. That threatened habitat and its limited range along the southern coast of Maine is why state officials wants to list it as threatened.

Climate change plays a role in the decline of the Blackpoll warbler and Bicknell's Thrush, both of which can be found in the high-elevation spruce-fir forests in western Maine. These birds are impacted by rising temperatures and precipitation swings, from storms to drought and back, that limit food supply.

The cliff swallow and bank swallow — two aerial insectivores that forage on flying insects — have suffered population collapses in recent years of approximately 97% and 99%, respectively, according to state wildlife biologists. This is exacerbated by the false springs that are becoming more common.

The dangerous thing about a false spring for swallows is that the inevitable temperature rightsizing, or a cold snap, causes the insects they rely on for food to go dormant. In one case, almost half a colony of cliff swallows died from starvation as a result of a cold snap that followed a false spring.

Stronger, more-frequent storms can cause erosion that threatens the dug-out homes of both the swallows and, in the case of the bank swallow, which spend its summers nesting in holes in the side of sand dune banks, rising sea levels pose an additional threat.

The tri-colored bat is the only list candidate threatened by something not directly tied to climate change. Like other cave-roosting bats already listed in Maine — northern long-eared, little brown, eastern small-footed — the tri-colored bat is threatened by an invasive pathogen that causes White-nose syndrome.

Here are the species on Maine's current endangered list:

Birds

— American pipit

— black tern

— golden eagle

— grasshopper sparrow

— least tern

— peregrine falcon

— piping plover

— roseate tern

— sedge wren

Mammals

— little brown bat

— New England cottontail

— northern long-eared bat

Reptiles

— black racer (snake)

— Blanding's turtle

Fish

— redfin pickerel

Butterflies

— Edwards' hairstreak

— Frigga fritillary

— Hessel's hairstreak

— Juniper hairstreak

— Katahdin arctic

Other invertebrates

— cobblestone tiger beetle

— Six-whorl Vertigo (snail)

Note: Not included are two species slated to be removed from the list: box turtle and rapids clubtail (dragonfly)