Latest news with #birdmigration
Yahoo
15-06-2025
- Science
- Yahoo
How do migrating birds know where they're going?
When you buy through links on our articles, Future and its syndication partners may earn a commission. Every year, billions of birds migrate in and out of the United States. And across the world, birds fly thousands of miles to reach their seasonal destinations. Some birds, like the Arctic tern (Sterna paradisaea), even rack up enough miles over their lifetime to fly to the moon and back. But when birds embark on these epic journeys, how do they know where they're going? Birds have an arsenal of senses they use to orient themselves — some we're familiar with, and some are still beyond human comprehension. "We know that birds use a variety of cues to keep their migratory direction," Miriam Liedvogel, director of the Institute of Avian Research in Germany, told Live Science in an email. Sign up for our newsletter Sign up for our weekly Life's Little Mysteries newsletter to get the latest mysteries before they appear online. Sight and smell are two basic cues that birds use to find their way. If birds have already migrated once, they'll likely remember familiar landmarks, such as rivers and mountain ranges. Birds that migrate over water, on the other hand, have fewer landmarks to guide them. In these circumstances, they might rely more on their sense of smell; one study found that when researchers blocked the nasal passageways of seabirds called Scopoli's shearwaters (Calonectris diomedea), they could still fly over land but became disoriented when flying over water. Birds also can use the sun and stars as guides. To do this, birds that fly during the day use a "sun compass," which combines birds' view of where the sun is in the sky with their internal perception of what time of day it is based on their circadian rhythm. By integrating these two inputs, birds can determine the direction they're heading, like a living sundial. Research shows that disrupting a bird's circadian rhythm with artificial light prevents them from navigating accurately, showing the importance of the sun compass. However, most birds actually migrate at night, meaning the position of the sun is of little use to them. In this case, birds rely on the position and rotation of the stars to find their way. They use this star compass by learning the position of the stars around the celestial pole, which is roughly marked by Polaris (the North Star) — the same star humans have used to navigate for millennia. Related: Why don't all birds fly? But what if the sky is cloudy, and birds can't see the sun, stars or any landmarks? That's when birds' more fantastic senses come into play. Birds can find their way even with no sun or stars, partly thanks to a sense called magnetoreception. This sense allows birds to perceive Earth's magnetic fields, which are generated by the rippling molten metals in our planet's core. This feat may sound like science fiction, but research shows that messing with magnetic fields has a big effect on birds; for example, one study found that altering the magnetic fields around pigeons disrupted their homing abilities. While it's clear that birds are capable of magnetoreception, exactly how they do it is less certain. Peter Hore, a professor of chemistry at the University of Oxford, said birds must utilize some sort of chemical reaction whose outcome depends on the strength and direction of Earth's magnetic field. There are a couple of candidate theories for how this reaction happens, but Hore's bet is on a molecule called cryptochrome, which is present in birds' retinas. Researchers have confirmed in the lab that isolated cryptochrome responds to magnetic fields and that this reaction requires blue light, which has also been shown to be necessary for bird magnetoreception. Still, researchers aren't exactly sure how cryptochrome is sensitive enough to pick up on tiny variations in Earth's magnetic field. "We know so little about the details of how this compass might operate," Hore said. "I mean, we don't even know how many cryptochrome molecules there are in the birds' retinas." Some research also points to a magnetoreception mechanism inside birds' beaks. Studies have found receptors that interact with magnetite, an iron-based mineral, in the upper portion of birds' beaks. These receptors connect to the brain via important nerve pathways, suggesting they could be another technique birds use to gauge the intensity of the magnetic field. On top of magnetoreception, birds can gain information about their direction by detecting polarized light — a type of light in which the waves oscillate in a specific, aligned plane. Sunlight becomes polarized in predictable ways when light scatters through Earth's atmosphere. Using special cells in their retinas, birds can sense these patterns, which give them information about where the sun is in the sky, even when it's overcast. Just as we rely on our vision during the day but may use our hands to guide ourselves around a dimly lit room at night, birds employ different senses at different times. "Birds likely integrate their compass cues to navigate — and we are pretty sure that different cues are of varying importance during their journey," Liedvogel said. Hore pointed this out as well; magnetoreception, for example, is less useful during thunderstorms or periods of high solar activity, both of which can disrupt Earth's magnetic fields, he said. RELATED MYSTERIES —Are birds reptiles? —Why do hummingbirds 'hum'? —Why are there so many pigeons? Ultimately, all of these strategies are underpinned by birds' genetic drive to migrate. Birds inherit the propensity to migrate from their parents, Liedvogel explained, and the distance and direction in which they fly are primarily based on genetics. Researchers like Liedvogel are still investigating exactly which genes are responsible and how they work. Both scientists said understanding these systems will be essential to the future of bird conservation. Relocating or rewilding bird species has become a major focus of wildlife conservation efforts, but so far, outcomes have been mixed; one analysis found that in 45% of studies, the birds left their new location. "Human efforts to relocate those birds have not been very successful," Hore said. "That's partly because they are such good navigators that if you displace them, they simply fly back."
RNZ News
02-06-2025
- Science
- RNZ News
The Chatham Island tui translocation
One from the archives! By the 1990s Chatham Island tūī had all but disappeared from the main island. Slightly different to their mainland counterparts these songbirds had survived on nearby Pitt and Rangatira islands. So a local conservation group decided to try bring them back. In this episode from 2010 Alison Ballance joins the ‘tūī team’ tasked with moving 40 birds from Rangatira island back to the main island. To embed this content on your own webpage, cut and paste the following: See terms of use.
Yahoo
24-05-2025
- Science
- Yahoo
Bird experts encourage people to turn off lights in peak migration season
The National Aviary and other bird experts are encouraging everyone to turn off or dim unnecessary lights at night. The request comes as we approach peak bird migration season. As many as 1 million birds could be passing over the Pittsburgh area in a single night. Birds are returning north to their breeding grounds for the warmer months. Ornithologist Bob Mulvihill said the lights can disorient the birds, leading to window collisions. 'They don't understand glass. It can both look transparent to them and they think they can fly through it, or it can fly through it, or it can look reflective to them and they think they are flying to their habitat. Either one has a bad consequence when they strike it,' Mulvihill said. Mulvihill said sometimes birds will end up circling lights in urban areas for hours at a time, thinking they are traveling somewhere else. Members of the Fox Chapel Wildlife Conservation Club are helping to spread the message by placing signs. About 75% of the birds will make their migration at night. Mulvihill said you can help your power bill go down while also helping the birds. Download the FREE WPXI News app for breaking news alerts. Follow Channel 11 News on Facebook and Twitter. | Watch WPXI NOW
Fast Company
21-05-2025
- Science
- Fast Company
Windows are the leading human cause of bird deaths. Here's how to help
When wood thrushes arrive in northern Mississippi on their spring migration and begin to serenade my neighborhood with their ethereal, harmonized song, it's one of the great joys of the season. It's also a minor miracle. These small creatures have just flown more than 1,850 miles (3,000 kilometers), all the way from Central America. Other birds undertake even longer journeys — the Swainson's thrush, for example, nests as far north as the boreal forests of Alaska and spends the nonbreeding season in northern South America, traveling up to 5,600 miles (9,000 kilometers) each way. These stunning feats of travel are awe-inspiring, making it that much more tragic when they are cut short by a deadly collision with a glass window. This happens with alarming regularity. Two recent scientific studies estimate that more than 1 billion birds – and as many as 5.19 billion – die from collisions with sheet glass each year in the United States alone, sometimes immediately but often from their injuries. In fact, window collisions are now considered the top human cause of bird deaths. Due to window collisions and other causes, bird populations across North America have declined more than 29% from their 1970 levels, likely with major consequences for the world's ecosystems. These collisions occur on every type of building, from homes to skyscrapers. At the University of Mississippi campus, where I teach and conduct research as an ecologist, my colleagues and I have been testing some creative solutions. Why glass is so often deadly for birds Most frequently, glass acts as a mirror, reflecting clear sky or habitat. There is no reason for a bird to slow down when there appears to be a welcoming tree or shrub ahead. These head-on collisions frequently result in brain injuries, to which birds often succumb immediately. In other cases, birds are stunned by the collision and eventually fly off, but many of those individuals also eventually perish from brain swelling. Other injuries, to wings or legs, for example, can leave birds unable to fly and vulnerable to cats or other predators. If you find an injured bird, contact a local wildlife rehabilitator. Which windows are riskiest Some windows are much worse than others, depending on their proximity to bushes and other bird habitats, what is reflected in them, and how interior lighting exacerbates or diminishes the mirror effect. On our campus, some buildings with a great deal of glass surface area kill surprisingly few birds, while other small sets of windows are disproportionately deadly. One particular elevated walkway with glass on both sides between the chemistry and pharmacy buildings is a notoriously dangerous spot. The glass kills migratory birds each spring and fall as they try to pass between the two buildings on their way to The Grove, the university's central-campus park area with large old oak trees. During the pandemic in 2020, student Emma Counce did the heart-heavy work of performing a survey of 11 campus buildings almost daily during spring migration. She found 72 bird fatalities in seven weeks. Five years later, my ornithology students completed a new survey and found 62 mortalities over the course of five weeks in 2025, demonstrating that we still have a lot of work to do to make our campus safe for migratory birds. Thrushes, perhaps due to their propensity for whizzing through tight spaces in the shady forest understory, have been disproportionately represented among the victims. Others include colorful songbirds – northern parulas, black-and-white warblers, prothonotary warblers Kentucky warblers, buntings, vireos and tanagers. The good thing is that everyone can do something to lower the risk. Films, stickers or strings can be added on the exterior of windows, creating dots or lines, 2 to 4 inches apart, that break up reflections to give the appearance of a barrier. Exterior screens and blinds work great too. Just adding a few predator silhouette stickers is not effective, by the way – the treatment needs to span the whole window. When applied properly, window treatments can make a huge difference. An inspiring example is McCormick Place in Chicago, the country's largest convention center, which notoriously killed nearly 1,000 birds in a single night in 2023. After workers applied dot film to an area of the building's windows equivalent to two football fields, bird mortality at the lakeside building has been reduced by 95%. The Bird Collision Prevention Alliance provides information on options for retrofitting home or office windows to make them more bird friendly. Options for new windows are also becoming more common. For example, the new Center for Science & Technology Innovation on my campus, which features many windows, mostly used bird-friendly glass with subtle polka dots built into it. This spring, we found that it killed only four birds, despite a very high surface area of glass. How you can help When trying to make a difference on your home turf, I suggest starting small. Make note of which specific windows have killed birds in the past, and treat them first. Use it as an opportunity to learn what approach might work best for you and your building. Either order a product or make something yourself and get it installed. Then do another, and tell a friend. At the office, talk to people, find others who care and build a team to make gradual change. With some creative solutions, anyone can help reduce at least this major risk.
The Guardian
15-05-2025
- General
- The Guardian
‘No one wants a building that kills birds': why cities are turning off the lights
The wren's legs were tucked delicately underneath its diminutive body, slumped on its side as if asleep. If it wasn't lying on the bare concrete of a Texas street, there would be few clues that it had endured a crunching, violent death. The bird had flown head first into the Bank of America building, a 72-storey modernist skyscraper in the heart of Dallas. Its corpse was catalogued by volunteers who seek to document the toll of birds that strike the glass, metal and concrete structures festooned with bewildering lights that form the skylines of our cities. It's estimated that around a billion birds die across the US each year in this way, one of the leading drivers of an alarming slump in numbers. For the dozen volunteers gathered before dawn to scour downtown for newly dead birds on a balmy May morning, each of these losses is a solemn one. 'If you let it sink in too much about what you're doing every morning, it wears you out, it can be pretty bleak,' says Tim Brys, a community engagement manager at the Perot Museum of Nature and Science and regular bird surveyor for the Lights Out, Texas! campaign. 'It's horrible to think these birds have flown all the way across the Gulf of Mexico only to fly into the first glass building.' The buildings of Dallas, along with those of other Texan cities, are particularly lethal obstacles because they sit on the central flyway, a major migratory route taken by birds as they traverse North and South America. It's thought as many as one in three birds migrating through the US each spring pass through Texas. 'That is a lot of birds,' says Brys. The Lights Out surveys take morning counts three times a week during the peak spring migration season – last year 295 mortalities were recorded. Volunteers have collected and tagged more than 100 species since 2020, including sparrows, doves, warblers, ovenbirds and more unusual finds such as a lazuli bunting or woodcocks, which are normally found in swamps. But there is no way to fully count such deaths, Brys admits, because birds are so regularly thumping into office towers, homes, power lines and, to a lesser degree despite some claims, wind turbines. The losses compound – each killed songbird might make up to six nests a season, with as many as six eggs in each nest. 'So the loss of one bird is 340 or so birds within a two-year span,' Brys says. For birds travelling from darker forests or grasslands, the sudden dazzle of lights and walls of glass found in cities can be a death trap. On maps charting US light pollution, Dallas is a burning beacon, sloshing light up and out of its buildings into the skies rather than focusing it on where it is needed. Most birds are nocturnal migrants, hardwired to navigate by the moon and stars, and the artificial replacements to these wayfinders, plus the reflections in glass, particularly of nearby trees that birds would aim for, cause many to become disoriented and crash into buildings. 'We had a security guard tell us that the birds run into the glass because they are effing stupid,' says Brys. 'And I said 'well, imagine trying to run through a mirror maze at 35mph, how far do you think you would get?' If we had never even seen glass before, how many people do you think would've walked into a glass door or window?' Light pollution has been present since the lightbulb was invented but it's only in the past 20 years that glaring, intrusive light has started to routinely obscure the stars and imperil birds flying at night, according to Teznie Pugh, superintendent of the University of Texas's McDonald Observatory. 'It's become a major concern,' Pugh says. 'Each generation, we are basically halving the number of stars you're able to see at night.' Globally, light pollution has increased by about 10% a year since 2011, a study released in 2023 found. But there has been some progress through a rethink of excess lighting, which is often costly as well as harmful, and the advance of bird-friendly glass, which incorporates dots or stripes to warn birds of an impending obstacle. Cities such as Houston and New York have vowed to lessen bird strikes, with the latter altering its annual 9/11 tribute, in which twin shafts of light are thrown towards the heavens, by switching off the lights for a short period if more than 1,000 birds are trapped, befuddled, in its beams. Chicago's McCormick Place, the largest convention centre in North America, became notorious when 1,000 birds slammed into it one night in 2023. 'That building is a real killer,' says Adriaan Dokter, an ecologist at the Cornell Lab of Ornithology. But the centre has since installed bird-safe glass, cutting the amount of crashes by about 90% last year. In Dallas, Reunion Tower, a landmark that resembles a giant golf ball on a stick, has dimmed its lights during peak spring migration season and activists are piling pressure on the city's convention centre to take action too. The sprawling building has plenty of darkened glass at bird-flying height, unhelpfully situated near stands of trees. The centre is undergoing a renovation and the Lights Out volunteers are agitating for it to install bird-safe glass. 'Nobody wants to be the building that kills tonnes of birds and a lot of times it a simple solution such as to turn off your lights or use a curtain,' says Mei Ling Liu, a Lights Out organiser at the Texas Conservation Alliance. Progress is complicated by ingrained habits of construction and lighting, exacerbated by LED lights, which are worse for birds and insects but are cheaper and more efficient. Bird-friendly glass also costs more than standard versions. 'It's a challenge,' adds Liu. 'When it comes to light pollution, it's not a single building issue, it's an entire city. And Dallas is still very bright.' As Dallas starts to emerge from its slumber, the hi-vis wearing volunteers continue to find birds on their circuit. A warbler is discovered thrashing on the ground at the foot of a hotel – it is placed into a brown bag to be sent to a rehabilitation centre. A young, dead grackle isn't so lucky, nor is another bird, a splattered warbler, that Liu has to pick up with tongs and shake because it is covered in ants. In all, 12 dead birds are recovered, placed in bags, logged and put into a freezer at the Perot museum, which installed bird-safe glass after some windows were smashed amid Black Lives Matter protests in 2020. A sort of silent spring has enveloped avians, with three billion fewer birds in North America than there were in the 1970s, a loss that researchers have called 'staggering'. Around a third of US bird species are in need to critical conservation action, with numbers plummeting fastest in places where they are most abundant. 'That the declines are steepest in these stronghold areas is really striking and remarkable,' says Dokter. 'We are seeing birds disappear at a rate that, ecologically speaking, is super fast.' The bald eagle and the California condor may have been saved from the brink of extinction but, more broadly, the days are marked by fewer birds now. Passenger pigeons, once so numerous they blotted out the sun while flying overhead, are completely wiped out. Our world has fewer songs, less colour and a dwindling sense of wonder as a result. A toxic tangle of reasons are behind this feathered crisis – habitat loss, chemical use and the climate crisis among them – but the one that appears most solvable is the tragedy of birds crashing into buildings. 'The nice thing about this problem is that it's within our reach to change quickly, it's not like climate change or plastic pollution,' said Dokter. 'Bird-safe designs of windows are the future and more and more cities are realising issues with lighting. We can all influence this, even in our own homes. We can tackle this problem.'
