Tag Archives: Climate change

Winter sets up breeding success: study

Winter sets up breeding success: Study

(Physorg; 20 March 2017)

For migratory birds, breeding grounds are where the action is. But a new study by University of Guelph biologists is among the first to suggest that the number of songbirds breeding during spring and summer depends mostly on what happens at their wintering grounds.

The pioneering study points to potential effects of climate change and may help conservation groups better protect migratory birds, including many species whose numbers have dropped in recent years, says Brad Woodworth, a PhD student in the Department of Integrative Biology and the study’s lead author.

The paper appears today in Nature Communications. Co-authors are U of G professors Ryan Norris and Amy Newman, and researchers in Maine and Switzerland.

Most researchers spend more time studying birds during the summer breeding season, but this study looked at how conditions in summer and winter homes affected population numbers of savannah sparrows.

The Guelph team used tiny tracking devices called geolocators to follow individual birds – each weighing about as much as three loonies – during migration over thousands of kilometres to and from their wintering grounds in the southern United States.

The researchers also used data collected since the late 1980s by researchers studying the sparrows during summer breeding at the Bowdoin Scientific Station on Kent Island in New Brunswick’s Bay of Fundy.

They found that wintering ground temperatures and population density at the breeding grounds are key factors affecting how many individuals return to breed on Kent Island each spring and summer.

That’s important information for biologists hoping to understand why populations of certain migratory birds have fallen in recent years, said Norris.

“What’s prevented us from learning has been lack of knowing where these birds go and what they do after leaving the breeding grounds,” he said.

Acknowledging that breeding grounds are usually more interesting and accessible to most researchers, he said the breeding season offers only a snapshot of a creature’s annual life cycle.

“Most birds are visitors to breeding grounds. They spend two to four months, they breed and they’re out of there.”

Not surprisingly, said Woodworth, warmer wintering grounds improve overall survival and encourage higher populations. But predictions of more frequent and severe weather caused by climate change suggest that any warming benefit may be outweighed by new threats.

“Even a harsh winter storm of a few days could put populations at jeopardy,” he said.

Norris said conservation organizations looking to protect habitat, including buying land or pushing for protected status for various species, might need to focus more on wintering ground conditions. Grassland birds, for example, are increasingly threatened by more intensive farming in their winter homes.

“You can only really make effective decisions about where to put resources for conserving migratory animals if you know what’s driving year-to-year fluctuations in their populations,” said Norris, noting that the study offers a model for studying other migratory animals from caribou to whales.

“We need to know what’s happening at both the breeding and non-breeding grounds. For many species like savannah sparrows, the non-breeding grounds might matter more.”

In life, ivory gull draws crowd—and in death, will contribute to science

Ivory gull flying ovef water

(Elliot Nelson; 17 March 2017)

On the evening of March 9, 2017, Lauren LaFave, 16, was walking across a bridge over the Flint River on the campus of the University of Michigan-Flint. LaFave noticed an unusually white bird resting on the bridge and was able to snap a few quick pictures on her phone. After those photos were shared among a number of Facebook groups it was confirmed that the bird photographed was, in fact, one of the rarest birds in all of North America, an ivory gull.

To understand the rarity of finding an ivory gull in downtown Flint, one must understand a bit about the species. The ivory gull is a bird rarely found south of the Arctic Circle. In North America, ivory gulls breed in the high arctic regions of Canada on bare rocks exposed only during the summer months. Unlike most arctic birds that head south for the winter, the ivory gull spends its winters remaining in the arctic. It can be found foraging on pack ice in the Bering Sea as well as the ice edge region between 50°–65° north latitude around Labrador and Greenland. The bird research database Birds of North American Online notes that only 2000-3000 of these birds breed in North America. It is listed in the 2014 State of the Birds report as being a species that will most likely become threatened or endangered unless conservation actions are taken. The species decline is due in part to declining sea ice associated with climate change as well as high mercury levels that accumulate in their tissue.

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Seabirds encounter natural changes in the ocean environment

Ancient Murrelets. Credit: Daniel Donnecke

(Spike Millington; March 13, 2017)

Seabirds encounter natural changes in the ocean environment, such as El Nino events that can affect the currents and bring warm or cold water, which in turn affect the distribution and abundance of prey species, such as fish and squid. However, the risk with global climate change is that such events become less predictable and possibly more regular, so that ability of seabird species to adapt can be affected, both in the short-term and long-term. This massive die-off of Common Murres (Guillemots) was due to unusually warm water temperatures affecting the birds’ food supply. If good conditions return, the seabirds can perhaps compensate with good breeding success and numbers can recover in the short-term. In the long-term however, the impacts of climate change-induced conditions are far from certain, requiring long-term monitoring to be able to assess patterns of response.

In a Hotter World, Desert Birds Will Face a Much Higher Risk of Dehydration

(Author: Meghan Bartels, Photo: Sandrine Biziaux-Scherson, February 13, 2017)

As the climate changes, desert-dwelling birds are going to need more oases than ever to stay cool and hydrated, according to a new study.

When the mercury soars, birds don’t really sweat it—but only because they can’t. Instead of sweating, birds harness the cooling power of panting, which expels excess heat by evaporating water.

“They have their beaks open and you can see them heaving, their bodies are going up and down,” says Deborah Finch, a U.S. Forest Service biologist who has studied desert birds. “You know that they’re feeling overheated.”

But cooling off comes at a price: water loss. Birds need to replace that water, and finding juicy fruits, juicy bugs, or another water source to replenish their reserves takes serious effort. If they can’t find water, birds sometimes die in the heat—an event that could grow more common as climate change causes an increase in hot days and their severity in many places.

To better understand what these changes could mean for birds, Thomas Albright, a geographer and biologist at the University of Nevada, Reno, did the math to figure out how much heat birds can take. “We’re almost acting like accountants, balancing the water budgets of these birds,” he says. His team knew from previous studies that if a bird loses more than 15 percent of its body weight in water, it will likely die. But they wanted to see how much climate change birds can take before they hit that limit. Their research was published today in the Proceedings of the National Academy of Sciences.

With the birds’ safety in mind, Albright’s colleagues designed an experiment to estimate how quickly birds grow dehydrated at higher temperatures. The team caught about 200 birds of five different species common in southwestern U.S. deserts. Then they put each bird in a closed chamber that measures water loss and cranked up the temperature.

The scientists ended the test after each bird lost around 10 percent of its body mass, allowing it to recover quickly and stay healthy. They found that the smaller species in the study (Lesser Goldfinches and House Finches) burned through their water reserves more quickly than the larger birds (Cactus Wrens, Abert’s Towhees, and Curve-billed Thrashers). This makes sense: the smaller birds started with less water, so they used up their reserves sooner. Meanwhile, the larger birds had bigger stockpiles that could last longer.

The team then mapped the locations where these birds faced high risk of dehydration today, and simulated what would happen if those areas grew hotter, assuming a 7.2°F (4°C) across-the-board temperature rise by the end of the century. That’s on the high end of estimates produced by the Intergovernmental Panel on Climate Change, but served as a starting point to let them examine birds’ responses.

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Study of songbird migrants demonstrates the importance of temperature in the decision to begin migration


(DE GRUYTER, 2017-02-10)

Around the world, no matter where we are, we can usually expect the weather to change from one season to the next. In North America, the warm days of summer eventually turn into the cooler days of  autumn, and these changes are vital to a lot of the animals that inhabit the region as they trigger the urge of animals to prepare for winter. Migratory animals, like songbirds, use these predictable weather changes as environmental cues to tell them when it’s time to migrate south. But with the earth now becoming warmer each year, birds can no longer rely on the once predictable climate.  As  autumns are becoming milder, ornithologists keep pondering on how it could be affecting birds’ migratory decisions. Now, a new study just published by De Gruyter’s online journal Animal Migration, has experimentally investigated how birds use temperature as a signal to migrate.

The study led by Adrienne Berchtold from the Advanced Facility for Avian Research at the University of Western Ontario, focused on one songbird species that is known to rely on weather for its migratory journey: the white-throated sparrow. The bird migrates from Canada to the southern United States each  autumn, and it tends to migrate later in the  autumn than other migrants, basing its journeys on when the weather provides opportunities for flight.

To figure out the underlying pressures that drive the birds to migrate, the researchers captured white-throated sparrows during one  autumn migration and placed them in specially-designed bird cages equipped with high-tech monitoring gear that kept track of how active the birds were by day and night. The scientists then changed the room temperature throughout the experiment to see how the birds would react. When the temperature dropped to chilly 4ºC, in an attempt to mimic the typical fall conditions in the northern part of the flyway, the birds all became restless at night, signifying they were in a migratory state. When, in turn, the temperature was raised to a warm 24ºC, none of the birds showed signs of migratory restlessness, indicating they were under no pressure to depart in these conditions.

These results will have considerable implications for the future of the migration as this and other bird species rely on predictable weather changes to leave home for the season. In North America, the continuous trend in soaring  autumn temperatures could delay the birds migration. Yet another more drastic possibility is that the birds would decide, perhaps unsurprisingly, to stay put and not to migrate at all. In fact, a recent paper in this same journal found this very pattern is happening in the population of American Robins of North America, who are increasingly deciding not to migrate.

According to Andrew Farnsworth, a Research Associate at the Cornell Lab of Ornithology who studies bird migration, “This type of research gives us more of the clues that scientists need to understand how birds respond, and might respond in the future, to changes in environmental conditions they experience. Considering these findings in light of previous research on nocturnal migratory restlessness from the mid to late 20th century, and more importantly, recent research on fuel accumulation and photoperiodicity, these results add to our growing understanding of how birds migrate and even how their migration evolved. Furthermore, given the predicted changes in global temperatures from human activities, these findings highlight the potential for dramatic changes to movements for many migratory species.

Impact of climate change on mammals and birds ‘greatly underestimated’

(University of Queensland, Michela Pacifici, Piero Visconti, Stuart H. M. Butchart, James E. M. Watson, Francesca M. Cassola & Carlo Rondinini, Science Daily,  February 13, 2017)

An international study published today involving University of Queensland research has found large numbers of threatened species have already been impacted by climate change

Associate Professor James Watson of UQ’s School of Earth and Environmental Sciences and the Wildlife Conservation Society said alarmingly, the team of international researchers found evidence of observed responses to recent climate changes in almost 700 birds and mammal species.

“There has been a massive under-reporting of these impacts,” he said.

“Only seven per cent of mammals and four per cent of birds that showed a negative response to climate change are currently considered ‘threatened by climate change and severe weather’ by the International Union for the Conservation of Nature Red List of Threatened Species.”

Associate Professor Watson said the study reviewed the observed impacts of climate change on birds and mammals using a total of 130 studies, making it the most comprehensive assessment to date on how climate change has affected our most well studied species.

“The results suggested it is likely that around half the threatened mammals (out of 873 species) and 23 per cent of threatened birds (out of 1272 species) have already responded negatively to climate change,” he said.

Lead author Michela Pacifici of the Global Mammal Assessment Program at Sapienza University of Rome said this implied that, in the presence of adverse environmental conditions, populations of these species had a high probability of also being negatively impacted by future climatic changes.

Associate Professor Watson said the study clearly showed that the impact of climate change on mammals and birds to date has been greatly under estimated and reported on.

“This under-reporting is also very likely in less studied species groups. We need to greatly improve assessments of the impacts of climate change on all species right now,” he said.

“We need to communicate the impacts of climate change to the wider public and we need to ensure key decision makers know significant change needs to happen now to stop species going extinct.

“Climate change is not a future threat anymore.”

Flying on Fumes: How Birds Meet Their Oxygen Demands at High Altitude

(Pat Leonard, February 23, 2017)

On top of Mt. Everest, at 29,000 feet, a lungful of air provides less than one-third as much oxygen as at sea level. To understand how birds cope with that lack of oxygen, or hypoxia, Cornell Ph.D. student Sahas Barve turned to the steep Himalayan valleys of his native India.

Over five years, he studied the evolutionary solutions these avian mountaineers had come up with. He and his colleagues published their findings in December 2016 in the journal Proceedings of the Royal Society B. Though he was working in the world’s tallest mountain range, Barve’s study focused on moderate elevations (up to 10,500 feet), meaning his findings are applicable to mountain species around the world—especially as it warms.

“One of the most common predictions of climate change is that species are going to shift upslope to get out of warmer temperatures,” Barve explains. But while moving upward may sound like a straightforward way to avoid warming, it ignores the problem of thin air. “If hypoxia is a major hurdle and birds cannot make their oxygen transport any better than they already have,” Barve says, “then it might severely limit their ability to adapt and shift their ranges higher.”

First, Barve and his hardy field assistants had to figure how the birds managed to compensate for thinner air. The researchers used mist nets to catch 15 species of birds at elevations ranging from 3,280–10,500 feet (1,000–3,200 meters). At these elevations, air has between 89 percent and 69 percent as much oxygen as at sea level.

They collected a drop of blood from each bird, allowing them to study the birds’ hemoglobin—the molecule in red blood cells that carries oxygen from the lungs to the muscles. The blood sample gave them two key measurements: the volume of the blood made up of red blood cells (hematocrit) and the hemoglobin concentration in the blood, measured using a handheld monitor.

The researchers tested resident species—ones that live at the same elevations year-round, such as the Green-backed Tit and Gray-winged Blackbird—and migrants, which breed at high elevations and spend winters lower down, including the Variegated Laughingthrush and the Blue-fronted Redstart. As it turned out, the two types of species solved the hypoxia problem in different ways.

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