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Posts Tagged ‘old-growth forests’

20180920_hermit-warbler-bird-decoy_greg-davis-f208c2c85f8d0a82d81fc01641221184b94fd12d-s600-c85

Photos: Greg Davis/OPB
Oregon State University doctoral student Hankyu Kim sets up a decoy of a hermit warbler. Songbird populations have been declining, and rising temperatures are one reason.

Nearly all birds are “canaries in the coal mine,” in the sense that when they’re in trouble from habitat destruction, rising temperatures, pollutants, and so on, they’re heralding trouble for all species, including the human one. For that reason, among many others, I love to hear of efforts to protect even one kind of bird.

Consider this story by reporter Jes Burns at National Public Radio (NPR).

“Each spring, songbirds migrate thousands of miles to breed in Oregon’s Cascade Mountains. Deep in a forest, Oregon State University researcher Hankyu Kim feels he has gotten inside the head of one species, the hermit warbler.

” ‘These birds are territorial in the breeding ground, they set up their territories, and they fight with each other to defend it,’ he says.

“Armed with this knowledge, a nearly invisible net strung between two repurposed fishing poles, a lifelike plastic warbler decoy and a looped recording of birdcalls, Kim’s trap is set. …

” ‘We have these long-term population monitoring routes across the Northwest. And a surprising number of species are declining,’ says Oregon State professor Matt Betts. ‘Actually, more than about half of the species that live in a forest like this are in decline.’

“Rising temperatures can shrink where some birds can live and where they can find food. For the hermit warbler, those declines are up to 4 percent each year.

“Research by Oregon State’s Betts and Sarah Frey found warblers declined in areas with young forests, including those replanted after clear-cut logging. But hermit warblers are doing better in other areas.

” ‘In landscapes that had more older forest, their population declines were lowered, or even reversed, even though the climate has been warming,’ Frey says.

“The Pacific Northwest has had a decades-long push to preserve its old-growth forests, and the warblers thrived in them. That suggests these forests somehow shielded them from the ill effects of rising temperatures. The question is why, and that is where this new study comes in.

“Kim and fellow Oregon State researcher Adam Hadley move the trapped hermit warbler’s feathers aside and attach a tiny radio tag to its back using nontoxic glue (the kind used for fake eyelashes). Then they release the bird, and it flies away. …

“They walk down a drainage though a 50-year-old tree plantation, a remnant of the logging past at the H.J. Andrews Experimental Forest. Then they cross into a grove of much older trees, some close to 300 years old.

“Hadley explains that the temperatures can be different at various heights of a tree. ‘It’s possible that when it’s warmer, [songbirds] may be only using the bottom and more shady parts of the trees,’ he says. He guesses they may move up higher when it becomes cooler.

“He says the complex layers and sheer biomass of old-growth keeps the temperature in these forests up to 5 degrees lower. But the researchers can’t fully understand what’s going on without knowing more about how the birds use the forests. …

“Hadley waves the antenna through the air trying to pinpoint the warbler’s location. … He and the others will compare the hermit warblers’ movements with temperature data they’ve also been gathering. They hope to get another step closer to understanding how this native songbird species might cope with the warming climate.”

More. This seems like an extra reason to protect old-growth forests, not just replant after logging. But how long will five degrees cooler be enough?

Kim, do you know about this? And are you seeing these warblers at your banding station?

Oregon State scientists are tagging and tracking hermit warblers in hopes of learning why their numbers have stabilized in places with old-growth forests, despite declines in other areas.

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