Category: biodiversity

Will global warming lead to a battle of the birds?

Mountain bluebird.
Mountain bluebird. @bberwyn photo.

Migration changes could affect competition for nesting sites

Staff Report

As global warming speeds up the springtime northward migration of swallows, it could spell trouble for mountain bluebirds.

Both species are cavity nesters; at times they compete for the same habitat. Historically, mountain bluebirds have arrived in the breeding territories earlier than the swallows, giving them a chance to defend their nests. But if the swallows arrive first, the bluebirds may have a harder time finding a safe spot to lay eggs, according to new research published in The Auk: Ornithological Advances.

The scientists from the University of Saskatchewan acknowledged that the outcomes of interspecies battles for nest sites depend on a number of factors, but wanted to study what happens when tree swallows and mountain bluebirds compete for nest sites. So they set up side-by-side pairs of nest boxes in grassland habitat in central British Columbia.

When bluebird and swallow pairs moved in next door to each other, they would either block the entrance to one box and let the two pairs of birds compete for the one that remained, or remove both boxes and replace them with a fresh one.

“I became interested in this topic after watching many competitive interactions over natural tree holes during a long-term study of Northern Flickers in central British Columbia,” said researchers Karen Wiebe. “In early spring when the birds are trying to claim a nest site, these disputes can be intense and really grab your attention. Because bluebirds and swallows readily use nest boxes, I was motivated to try some experiments in a system where I could have more control over the spacing of nests and settlement patterns of the birds.”

Wiebe found that when Tree Swallows were defending their previously owned box or when the two species were competing over a new box, Tree Swallows won 65-70 percent of the time. Bluebirds got a boost when they defended a box they already occupied, however, fending off swallows 77 percent of the time.

Climate change may bring the two species into direct competition more often and reduce bluebirds’ ability to claim and defend nest sites.

“This is a nice set of clever and simple experiments that show that species are not the same when it comes to the importance of being the first one to occupy a nest site,” according to ecologist Hanna Kokko of the University of Zurich, an expert on interspecies competition in birds. “The one that currently tends to arrive first, the bluebird, relies more on this, which could easily cause problems if the arrival order changes on a changing planet.”

New report shows how global warming will affect birds and reptiles in the Southwest.

 red-tailed hawk
Global warming will take a toll on reptiles and birds in the Southwest. @bberwyn photo.

Many bird species could lose between 78 and 85 percent of their existing habitat

Staff Report

Birds and reptiles in the Southwest that live in fragmented habitat will be hit hardest by global warming in the decades ahead, according to a new study by scientists with the U.S. Geological Survey and the Northern Arizona University.

The researchers took a close look at about 30 different animals, including well-known species such as the Gila monster, horned lizard, chuckwalla, Sonoran desert tortoise, pinyon jay, pygmy nuthatch, sage thrasher and black-throated sparrow.

A few species could see their habitat expand as the climate warms, but many others will be hit hard by global warming. Most climate models project temperatures to increase by about 6 degrees Fahrenheit in the Southwest in the next century, while precipitation is expected to decline by between 5 and 20 percent. Continue reading “New report shows how global warming will affect birds and reptiles in the Southwest.”

Eruption poses threat to huge penguin colony

chinstrap penguin
A chinstrap penguin on Deception Island. @bberwyn photo.

British Antarctic Survey scientists to monitor impacts of ash deposits

Staff Report

A volcanic eruption in the remote South Sandwich archipelago, near the tip of the Antarctic Peninsula, may threaten the largest known colony of chinstrap penguins, according to scientists with the British Antarctic Survey who have been monitoring the eruption.

The Mt. Curry volcano on Zavodovski Island has been erupting since March, sending ash toward the penguin enclave. The uninhabited island is part of the British Overseas Territory of South Georgia and the South Sandwich Islands. After reports of a 7.2 magnitude earthquake last month, researchers confirmed from satellite imagery that not one, but two volcanoes are erupting in the South Sandwich Islands — Mt. Curry on Zavodovski Island to the north of the archipelago and Mt. Sourabaya on Bristol Island to the south. Continue reading “Eruption poses threat to huge penguin colony”

Conservation groups seek trade sanctions against Mexico in effort to save the endangered vaquita

Continued illegal gill net fishing cited in push for ban on Mexican seafood

vaquita
There may be as few as 60 endangered vaquita remaining in the Gulf of California. Photo courtesy NOAA.

Staff Report

In what could be a last-ditch effort to save imperiled vaquita in the Gulf of California, conservation advocates are urging the Obama administration to launch economic sanctions against Mexico to halt that country’s trade in totoaba. According to the Center for Biological Diversity, the sanctions would be justified because Mexico is violating the Convention on International Trade in Endangered Species (CITES) by not enforcing the ban on totoaba trade.

The June 28 letter to high level U.S. Cabinet officials is the latest step in a long-running an complex struggle to prevent extinction of vaquitas, an endangered porpoise that lives in only a small section of the upper Gulf of California. My some estimates, there may only be 60 individuals remaining. Continue reading “Conservation groups seek trade sanctions against Mexico in effort to save the endangered vaquita”

Reaching Paris climate goals would help polar bears survive

New research suggests that capping global warming below 2 degrees Celsius would lower chances of big population decline by preserving critical sea ice

 Eric Regehr, U.S. Fish and Wildlife Service
Can these mighty Arctic predators survive the era of human-caused global warming?  Photo courtesy Eric Regehr, U.S. Fish and Wildlife Service.

Staff Report

Now that the world has a clear target for limiting global warming, scientists say they show how how achieving the goal would protect at least some ecosystems and vulnerable species from impacts.

One newly updated study found that aggressively cutting greenhouse gas emissions would help ensure the survival of polar bears, listed as threatened because of Arctic sea ice declines. Polar bears depend on the ice as platforms for feeding around the biologically rich continental shelves of the Arctic Ocean. Continue reading “Reaching Paris climate goals would help polar bears survive”

Sunday set: Changing world

Global warming will irrevocably alter the face of the Earth

The more I report on climate change and the environment, the more I learn to cherish the landscapes that I see, because it’s really starting to sink in that humankind, during this Anthropocene Age, is fundamentally changing Earth’s ecosystems, altering the climate and impacting the landscape on levels seem almost inconceivable.

Take the Danube River (or most other major rivers, for that matter), where I spent a few hours Saturday afternoon swimming to cool of from a hot summer day in the city. While the water offered cool relief, I couldn’t stop thinking about a story I wrote a few years ago about scientists who discovered how, at times, there’s more plastic pollution than fish larvae in Europe’s second-biggest stream.

And watching sunset colors tinge the Ötscher, the highest peak peak in the eastermost reaches of the Alps, was a reminder that global warming is inexorably changing mountain ecosystems to the detriment not only of nature, but to ancient agricultural practices that are a culturally important part of life in the Alps. Continue reading “Sunday set: Changing world”

Bleaching risk on the rise for Great Barrier Reef corals

Global warming is likely to overwhelm corals'
Global warming is likely to overwhelm corals’ built-in thermal tolerance mechanisms within the next few decades, leading to more bleaching and mortality. Photo courtesy Dr. Peter Mumby.

Study identifies bleaching and mortality thresholds for imperiled coral reefs

Staff Report

The steady rise in ocean temperatures projected for the next few decades will put more and more corals at risk of bleaching, as the warm water simply overwhelms their thermal tolerance mechanisms.

Recent research along the Great Barrier Reef shows that corals have been able to survive past bleaching events because they were acclimated to warmer temperatures by being exposed to a pattern of gradually warming waters in the lead up to each episode. But global warming is likely to change that, the scientists said.

Before long, temperature increases of as little as 0.5 degrees Celsius may push many corals over the edge as the warm water causes them to expel the algae-like dinoflagellates that help keep them alive and give them their color.

Lead author Dr. Tracy Ainsworth from Coral CoE said  bleaching is like a marathon for corals.

“When corals are exposed to a pre-stress period in the weeks before bleaching, as temperatures start to climb, this acts like a practice run and prepares the coral. Corals that are exposed to this pattern are then less stressed and more tolerant when bleaching does occur,” Ainsworth said. Continue reading “Bleaching risk on the rise for Great Barrier Reef corals”