Category Archives: International

Migrating birds use a magnetic map to travel long distances

Migrating birds use a magnetic map to travel long distances
(Richard Holland 18 August 20017)

Birds have an impressive ability to navigate. They can fly long distances, to places that they may never have visited before, sometimes returning home after months away.

Though there has been a lot of research in this area, scientists are still trying to understand exactly how they manage to find their intended destinations.

Much of the research has focused on homing pigeons, which are famous for their ability to return to their lofts after long distance displacements. Evidence suggests that pigeons use a combination of olfactory cues to locate their position, and then the sun as a compass to head in the right direction.

We call this “map and compass navigation”, as it mirrors human orienteering strategies: we locate our position on a map, then use a compass to head in the right direction.

But pigeons navigate over relatively short distances, in the region of tens to hundreds of kilometres. Migratory birds, on the other hand, face a much bigger challenge. Every year, billions of small songbirds travel thousands of kilometres between their breeding areas in Europe and winter refuges in Africa.

This journey is one of the most dangerous things the birds will do, and if they cannot pinpoint the right habitat, they will not survive. We know from displacement experiments that these birds can also correct their path from places they have never been to, sometimes from across continents, such as in a study on white crowned sparrows in the US.

Over these vast distances, the cues that pigeons use may not work for migrating birds, and so scientists think they may require a more global mapping mechanism.

Navigation and location

To locate our position, we humans calculate latitude and longitude, that is our positon on the north-south and east-west axes of the earth. Human navigators have been able to calculate latitude from the height of the sun at midday for millennia, but it took us much longer to work out how to calculate longitude.

Eventually it was solved by having a highly accurate clock that could be used to tell the difference between local sunrise time and Greenwich meantime. Initially, scientists thought birds might use a similar mechanism, but so far no evidence suggests that shifting a migratory bird’s body clock effects its navigation ability.

There is another possibility, however, which has been proposed for some time, but never tested – until now.

The earth’s magnetic pole and the geographical north pole (true north) are not in the same place. This means that when using a magnetic compass, there is some angular difference between magnetic and true north, which varies depending on where you are on the earth. In Europe, this difference, known as declination, is consistent on an east west axis, and so can possibly be a clue to longitude.

To find out whether declination is used by migrating birds, we tested the orientation of migratory reed warblers. Migrating birds that are kept in a cage will show increased activity, and they tend to hop in the direction they migrate. We used this technique to measure their orientation after we had changed the declination of the magnetic field by eight degrees.

First, the birds were tested at the Courish spit in Russia, but the changed declination – in combination with unchanged magnetic intensity – indicated a location near Aberdeen in Scotland. All other cues were available and still told them they were in Russia.

If the birds were simply responding to the change in declination – like a magnetic compass would – they would have only shifted eight degrees. But we saw a dramatic reorientation: instead of facing their normal south-west, they turned to face south-east.

This was not consistent with a magnetic compass response, but was consistent with the birds thinking they had been displaced to Scotland, and correcting to return to their normal path. That is to say they were hopping towards the start of their migratory path as if they were near Aberdeen, not in Russia.

This means that it seems that declination is a cue to longitudinal position in these birds.

There are still some questions that need answering, however. We still don’t know for certain how birds detect the magnetic field, for example. And while declination varies consistently in Europe and the US, if you go east, it does not give such a clear picture of where the bird is, with many values potentially indicating more than one location.

There is definitely still more to learn about how birds navigate, but our findings could open up a whole new world of research.

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Stress in the nest can have lifelong effect

(The Norwegian University of Science and Technology, Science Daily 16 August 2017)

Why do some sparrows hatch six chicks while others don’t hatch any? How does upbringing affect the remainder of their lives? Physiological stress in the nest can actually affect birds’ DNA and possibly their lifespan.

On average, a mere 10 to 20 per cent of sparrow nestlings survive until the next breeding season. But the survival rate varies between different parents, according to Thomas Kvalnes and Michael Pepke Pedersen at the Norwegian University of Science and Technology’s (NTNU) Centre for Biodiversity Dynamics (CBD).

In order to learn more about this variation, they’re studying birds by banding them.

Good conditions in NTNU birdhouse

At the NTNU Gløshaugen campus in Trondheim, Kvalnes and Pedersen have been following a pair of Eurasian blue tits, which eventually laid ten eggs and were incubated for two weeks. Then the real work started for the parents. No fewer than nine chicks hatched and they all wanted to eat — at the same time.

The blue tit chicks — which are part of the sparrow family — grew enormously fast during the nesting period, growing from less than one gram at hatching to 10 to 12 grams at around 15 days old. This requires a lot of food. The parents in the NTNU birdhouse seem to have access to good nutrition, because all nine young were alive and growing normally when they were 12 days old.

Banding for research

By the age of 12 days, the young had a lot of feathers and were able to regulate their body temperature well. They were also small enough not to get scared and fly out when the lid on the birdhouse was opened. This is important to think about when banding chicks, because the bands must not adversely affect the birds.

The researchers banded all nine baby birds with metal rings, each having a unique identity number. This allows researchers to recognize the individuals later and to follow their development throughout their lives.

Banding is a widely used method by researchers at the NTNU’s Centre for Biodiversity Dynamics.

How does upbringing affect the rest of a bird’s life?

New research suggests that the first days and weeks have a big impact on how the rest of a bird’s life unfolds. In some clutches, the young get a lot of food and grow fast, whereas in others the chicks face tougher competition or the nest is more exposed to the weather. However, conditions in the nest can actually leave a genetic impression in the birds, more specifically on the ends of the chromosomes that make up the DNA.

The telomeres (from Greek, meaning “end pieces”) that protect the DNA from breaking down are found here, say Kvalnes and Pedersen.

“Each time a cell divides, the DNA must be copied, but the entire DNA sequence cannot be copied, and that impacts the telomere structures, which get shorter after each copying. At the same time, the telomeres wear down if exposed to oxidative or physiological stress, the researchers say.

Molecular thread of fate?

When the telomeres become too short, cell function may become impaired and the entire organism may be affected by age-related illnesses. Some studies have shown that birds’ telomere length can predict how long they will live — a bit like the thread of fate that is clipped by the Norns in Norse mythology and decides the length of human lives.

The most rapid shortening of the telomeres in life occurs when the young chicks grow fast. At CBD, researchers are investigating the connection between sparrow telomeres and their life stories. The researchers follow them from their time in the nest until they become parents themselves — and perhaps grandparents — until their death.

Telomeres in birds and humans

Much of our understanding of telomeres comes from studies of animals in captivity or laboratories, but there’s a lot we don’t know about how these fundamental physiological processes work in typical natural circumstances. CBD researchers hope to help answer these questions.

“The telomeres in birds are identical to those found in humans and all other vertebrates, and they speak to our common origin. In fact, telomere mechanisms exist in all organisms except simple bacteria and archaea. So it’s conceivable that we’ll be able to transfer our knowledge of telomere dynamics in birds to many other organisms,” the researchers say.

What’s the catch? The fate of Europe’s seabirds

seabird.jpg(Bruna Campos 14 August 2017; Photo David Grémillet )

Bruna Campos explains why a ‘sea change’ in policy is needed to protect thousands of Europe’s seabirds from the threat of incidental bycatch in fishing gears.

Uneasy lies the head that wears a crown”, Shakespeare famously wrote – and though the great playwright was reflecting upon the power of princes, at BirdLife these words turn our thoughts to the plight of petrels…and shearwaters, and the seabirds that together carry the unwanted crown anointing them the most threatened bird group in the world.

Marine biodiversity is facing enormous pressure from a wide range of human activities that lead to habitat destruction and pollution. And a huge part of the problem is seabird ‘bycatch’, with an estimated 200,000 seabirds accidentally caught and killed by commercial fishing hooks and nets each year. Many of Europe’s 82 seabird species are at risk, but some species seem to be far more susceptible than others – for example, Steller’s and Common Eider, Long-tailed duck and Velvet scoter are regularly caught in gillnets in the Baltic, while Northern Fulmar and Great shearwater are menaced by demersal longline fishing off the coast of Western Scotland, Ireland and France. It is particularly alarming that already threatened species are being put into further peril; such is the case for several seaduck species (in dramatic decline in recent years) and also for the Balearic shearwater – Europe’s most threatened seabird.

“…an estimated 200,000 seabirds [are] accidentally caught and killed by commercial fishing hooks and nets each year.

Out at sea, BirdLife’s conservation team and our ‘Seabird Task Force’ are working with fishermen to overcome practical challenges through pioneering technical innovation. Nonetheless, bycatch of seabirds – and also many marine mammals and sea turtles – continues despite existing EU regulations. Improvements are clearly needed here on dry land before we will see a sea change in our fisheries.

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How Much Should Major Polluters Pay? A Case Against DuPont Provides a Model

(Paul Greenberg 16 Aug 2017; Photo Greg Kahn)

A biologist traced mercury from a company spill to contamination in songbirds, and devised a new way to hold polluters financially accountable.

It was just another sweltering summer afternoon gathering blood samples from Shenandoah Valley birds when the news came in. The ornithologist Dan Cristol had been conducting a preliminary assessment funded by DuPont to determine to what degree the company’s pollution of the watershed might have affected the avian community. DuPont was facing potential legal action and had cautiously agreed to one summer of funding for a small team to gauge just how expensive fixing the damages might be. True to his nature, Cristol hadn’t been tentative in his research. He and his students had skulked into stream-bank kingfisher nests, cornered screech owls near bridges, and mist-netted dozens of species of songbirds. Using tiny needles, they’d extracted drops of bird blood before gently releasing their subjects back into the wild. Then they’d shipped their samples to a toxicology lab at Texas A&M, and watched as their funding dribbled away at a rate of $55 per analyzed sample.

Now as the sun blazed over the South River, a major tributary of the mighty Shenandoah, and waves of heat rose up from the newly mown hayfields, Cristol opened an email from the lab and read the first test results.

“Holy fucking shit,” one of the students cried out.

“I rechecked the numbers about five times to make sure,” Cristol recalls. “We were being funded by the responsible party, so I figured DuPont would look at what we’d found and say, ‘OK, thanks but no thanks, we’ve seen enough.’ I was worried that after this tantalizing glimpse we would not get to learn what was really going on. But to their credit, everyone just kept moving forward and letting us propose to answer each new question that arose.”

Cristol and his students had discovered that the DuPont mercury spill had penetrated much further into the avian food web than anyone had previously expected. Not only was mercury found in fish-eating raptors like osprey and eagles, but it was present in bluebirds that flitted far away from the contaminated South River; it was in surprisingly high levels in the feathers of the distinctly non-riverine Red-eyed Vireo whose song tells you to look-up way-up tree-top to find it; it was in scrappy Carolina Wrens, whirling Tree Swallows, and reclusive thrushes. Even in the diminutive Blue-gray Gnatcatcher that weighs in at a miniscule third of an ounce.

More importantly, the work had laid the foundation for a novel way to restore North American songbird populations that are declining throughout the country. For Cristol’s research has ultimately perfected a way of holding major polluters accountable for something as profound as it has long been intangible: a means to calculate and seek reparations for bird years lost.

“You couldn’t have a better site to test the effects of methylmercury,” Cristol told me as we stood on a bridge over the South River in the City of Waynesboro and stared southeast at a 177-acre chemical plant. For roughly 50 years this gray smudge of a facility, built into the green hillsides by DuPont in 1928, manufactured something called acetate fibers—which used mercury as a catalyst for the first 20 years of its operation.

DuPont to its credit has never strongly contested that it put significant amounts of mercury into the South River. Ever since mercury was detected in river sediment and floodplain soil around the plant in the 1970s, the corporation has been trying to figure out a way to put its pollution legacy behind it. For years DuPont funded a vaguely missioned “South River Science Team” where state officials and academics monitored mercury levels in fish, with the hope that concentrations would eventually go down. No such decrease was observed. Sampling continued to show levels in some fish higher than 4 parts per million—nearly four times that found in swordfish, which the FDA urges consumers to avoid because of high mercury levels. Nevertheless, officials representing the State of Virginia (technically the key plaintiff in these early proceedings) seemed at a loss as to what to do next.

“They had been completely bamboozled,” says Nancy Marks, a senior attorney for the nonprofit Natural Resources Defense Council’s litigation team. Under Marks’s direction NRDC filed an intention to sue DuPont in the early 2000s to move the issue forward from monitoring to mitigation. “[DuPont’s] remedy was to have a hundred year monitoring program. But we knew the mercury in the river was sky high. And DuPont was the only obvious source.” Unlike other American watersheds that have been host to numerous polluters, the Waynesboro DuPont plant is all the mercury-discharging industry the South River basin ever had. The bulk of the mercury in the ecosystem and any harm it may have caused birds is undeniably DuPont’s fault.

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Canary in a coal mine: Survey captures global picture of air pollution’s effects on birds

(University of Wisconsin-Madison, Physorg 11 August 2017; Photo: Jeff Miller)

Famously, the use of caged birds to alert miners to the invisible dangers of gases such as carbon monoxide gave rise to the cautionary metaphor “canary in a coal mine.”

But other than the fact that exposure to toxic gases in a confined space kills caged birds before affecting humans — providing a timely warning to miners — what do we know about the effects of air pollution on birds?

Not as much as you’d think, according to researchers from the University of Wisconsin-Madison.

“We know a lot about air pollution’s effects on human health, and we know a lot about the impacts of air pollution across ecosystems,” explains Tracey Holloway, a professor in UW-Madison’s Nelson Institute for Environmental Studies. “We were surprised to discover how little we know about how air pollution affects birds.”

Writing Aug. 11 in the journal Environmental Research Letters, Holloway, an expert on air quality, and her former graduate student Olivia Sanderfoot, sort through nearly 70 years of the scientific literature to assess the state of knowledge of how air pollution directly affects the health, well-being, reproductive success and diversity of birds. This work is part of Sanderfoot’s ongoing National Science Foundation Graduate Research Fellowship.

According to the Wisconsin team’s survey of the literature, only two field studies since 1950 have looked at any aspect of the health and ecological well-being of wild bird populations in the United States. Globally, there are only a handful of studies that assess the impact of direct exposure to air pollutants on bird health. Those encompass studies of just a few dozen bird species of the roughly 10,000 or so species of birds known worldwide.

Part of the problem, says Sanderfoot, are the many variables in play. Not only are studies of wild bird communities difficult to implement, but factors such as types and levels of air pollution, dynamic atmospheric conditions, species-specific responses, and the difficulty of teasing out direct versus indirect effects of air pollution can confound even the most basic efforts to assess how birds fare when exposed to chemicals in the air.

“There is a lot of work to be done in this area,” says Sanderfoot. “Air quality is an ever-changing problem across the globe. There’s a need to look at different types of air pollution and different species all over the world. We have a huge lack of understanding of the levels of pollution birds are exposed to.”

Gaps in our understanding, according to the new study, include air pollution’s effects on the avian respiratory system; toxic effects on birds, including elevated stress levels and immunosuppression; behavioral changes; and effects on reproductive success and demographics, such as changes in population density, species diversity and community composition.

Holloway, who leads the NASA Health and Air Quality Applied Sciences Team (a multi-institutional team of researchers that serves as a nexus for analyzing environmental data from a constellation of Earth-observing satellites), notes that studying the effects of air pollution on humans is comparatively easier to assess as hospital records and mortality data are readily available to scientists. Air pollution, in fact, is one of the leading and most direct environmental threats to human health, she says.

Something that makes birds potentially more vulnerable to atmospheric contaminants is the efficiency of the avian respiratory system.

“Birds breathe unidirectionally,” notes Sanderfoot. “They definitely breathe more efficiently than humans, and it has been hypothesized that because their respiratory system is so much more efficient than ours, they are going to more readily pick up air pollutants.”

The study is a springboard for new research, Sanderfoot and Holloway argue, and may be especially important given birds’ role as sentinel species in the environment.

“When you talk to bird ecologists, air pollution is not necessarily perceived as a high-level issue,” Holloway says. “Things like climate and landscape changes are at the top of their list in terms of population densities, species diversity, ecological stress. But we know that air pollution is a major risk to human health, and from our study we see pretty clearly that there is an impact on birds, too.”

New Government Report Contradicts Trump Administration Climate Claims

Common Loon with chicks. Photo: Richard D. Pick/Audubon Photography Awards(Andy McGlashen 8 August 2017)

The report, which paints a dire picture of the planetary changes caused by warming temperatures, is awaiting official White House approval. But scientists worry its findings will be downplayed or suppressed.

The White House has found itself in yet another tough spot: Will the president and cabinet officials approve a report that contradicts their own public statements about climate change, or face backlash for suppressing the report and its inconvenient conclusions? Either way, they only have until August 18 to make a decision, and a sudden frenzy of news coverage this week has increased pressure as the deadline looms.

As originally reported by The New York Times on Monday, the draft report from scientists at 13 federal agencies shows severe warming in recent years, projects continued, significant temperature increases, and says human activity is chiefly to blame. According to the Times, scientists involved in the study are concerned that the Trump administration will hide or downplay the findings of the report, which was publicly available during its review period in December but received little press coverage until now.

Trump infamously called climate change a Chinese hoax during his campaign for the White House, has since moved to undo domestic climate policies, and has pulled the United States out of the Paris climate accord signed by nearly 200 countries in 2015. He also made Scott Pruitt the administrator of the Environmental Protection Agency. Pruitt, who is a known climate change denier, would need to approve the report before it went public. Pruitt has spent much of his time in office weakening the EPA’s climate change research, and as the Times notes, in March, he said that carbon dioxide is not a “primary contributor” to global warming.

The draft report thoroughly undermines the Trump administration’s climate change claims and policies. “Evidence for a changing climate abounds, from the top of the atmosphere to the depths of the oceans,” it says. “Many lines of evidence demonstrate that human activities, especially emissions of greenhouse (heat-trapping) gases, are primarily responsible for recent observed climate changes. There are no alternative explanations, and no natural cycles are found in the observational record that can explain the observed changes in climate.” You can read the full report here.

Our planet has warmed by 1.6 degrees Fahrenheit since 1880, and it is “extremely likely” that most of the 1.2 degrees of warming since 1951 is due to human activity, the report concludes. We could expect another half-degree of warming by the end of the century, even if humans stopped pumping greenhouses gases into the atmosphere today. And under more realistic emissions scenarios, “the temperatures of recent record-setting years will become relatively common in the near future,” the authors write.

Along with rising temperatures, the report paints an unsettling picture of other planetary changes already underway. In the northeastern U.S., for example, extreme precipitation events are 17 percent more frequent than they were in the first half of the 20th century. Global sea levels have risen 3 inches since 1990, and the oceans are becoming more acidic faster than at any period in the past 66 million years. Permafrost is thawing and sea ice is melting in the Arctic, which is warming more than twice as fast as the rest of the planet. “Residents of Alaska are on the front lines of climate change,” the report says. “Crumbling buildings, roads, bridges, and eroding shoreline are commonplace.” 

While most scientists have long been cautious about blaming climate change for specific weather events, the report notes that new tools and techniques are making it possible to detect its influence on specific extreme weather events.

In addition to being a danger to human life, especially the socioeconomically disadvantaged, the global changes documented in the report threaten birds and other wildlife. As Audubon has reported, warming oceans are changing seabird diets and possibly even causing die-offs, while rising seas threaten bird habitat. And Audubon’s 2014 Birds & Climate Change Report, published in peer-reviewed scientific journals, found that climate change is the biggest threat to 314 North American bird species. In South America, where many of these species migrate for the winter, climate change-related droughts also put birds at risk.

The draft Climate Change Special Report is part of the National Climate Assessment charged with reporting the latest climate science to Congress and the president every four years. The National Academy of Sciences has approved the draft, but it won’t be final until the White House signs off. If the administration did have plans to quietly scuttle the report or water down its urgent message, it will now have a much harder time doing so.

Deadly Pesticide May Yet Be Outlawed

Deadly Pesticide May Yet Be Outlawed

American Bird Conservancy 25 July 2017

We applaud the U.S. Senators who today introduced a bill to ban chlorpyrifos, a widely used pesticide that has been killing birds and poisoning the environment for the past half-century: Tom Udall (D-NM)Kirsten Gillibrand (D-NY), Cory Booker (D-NJ), Richard Blumenthal (D-CT), Kamala Harris (D-CA), and Edward J. Markey (D-MA). We’re also grateful to Representatives Nydia Velazquez (D-NY) and Keith Ellison (D-MN), who have offered a companion bill in the House.

The “Protect Children, Farmers & Farmworkers from Nerve Agent Pesticides Act” would prohibit all chlorpyrifos use by amending the U.S. Federal Food, Drug, and Cosmetic Act that oversees food safety.

Chlorpyrifos, an organophosphate related to sarin nerve gas, is used in production of common crops such as strawberries, apples, citrus, and broccoli. In addition to the pesticide’s well-known threats to human health, American Bird Conservancy (ABC) is concerned about the pesticide’s effects on birds, including to declining species like the Mountain Plover (shown). A recent draft biological evaluation from the Environmental Protection Agency (EPA) stated that chlorpyrifos is likely to adversely affect 97 percent of all wildlife, including more than 100 listed bird species listed under the Endangered Species Act.

ABC has been calling for a ban on the use of chlorpyrifos for years. EPA scientists agreed and were on course to ban the pesticide from use on all crops. In March 2017, however, the EPA administrator reversedw the recommendation of the agency’s own scientists and extended chlorpyrifos’ registration for another five years.

“It’s high time to outlaw the use of chlorpyrifos. It’s well known that this pesticide is lethal to birds, other wildlife, and people,” said Cynthia Palmer, ABC’s Pesticide Program Director. “We’re encouraged by the leadership shown today in Congress.”