Chook migrations rank as certainly one of nature’s best spectacles. Due to GPS monitoring, scientists are uncovering extraordinary insights into historical and mysterious journeys – and new threats which are reshaping them.
As storm-chasing seabirds, Desertas petrels search out hurricanes that draw deep-sea creatures to the floor. Solely about 200 pairs stay, though the inhabitants is steady.
Every chook isn’t any larger than a pigeon they usually all breed on a single abandoned island off the west coast of north Africa, fanning out throughout the Atlantic Ocean to forage.
Among the many 35 birds which have been tracked by GPS is “Marlo”, which was born on Bugio Island and tagged after returning there in 2019. Men and women are just about indistinguishable, so researchers have no idea the intercourse of Marlo however we are going to seek advice from him as “he”.
Marlo is a part of a pair bonded for all times, and he and his companion reunite with a flurry of pleasure after months aside, preening and calling to one another. The dad and mom increase one chick as a tag group, doing lengthy shifts at sea for as much as three weeks at a time, protecting distances of as much as 7,400 miles (12,000km). They gorge on seafood and regurgitate it as oil for his or her chick.
Francesco Ventura, from the Woods Gap Oceanographic Establishment in Massachusetts, says: “The routes they take are among the longest collected for any animal throughout breeding season. It’s like travelling to the opposite aspect of the Atlantic for a meals store.”
As soon as his chick efficiently fledged, Marlo departed Bugio on 2 November 2019, and didn’t contact land till June of the next 12 months. Like all Desertas petrels, Marlo spends the vast majority of his life hovering above worldwide waters.
Sometimes, the younger spend the primary few years of their life out at sea with out touching land. Nobody is aware of the place they go. In the event that they survive these early years, they sometimes reside for many years.
In September 2019, Marlo flew out over the Atlantic Ocean and got here throughout the cyclone that was growing into Tropical Storm Gabrielle. Researchers tracing their migrations have found that petrels actively steer into storms, maybe studying adjustments in air stress, cloud patterns and the swell of waves to seek out them.
“To me, this seems like intentionality,” says Ventura, who was a part of the first team of researchers to track this behaviour in Desertas petrels.
For 19 days, Marlo chased the tropical storm’s wake, protecting practically 7,000 miles and reaching speeds of 41mph (66km/h). Hurricanes churn up chilly, nutrient-rich water, which pulls deep-sea squid and crustaceans to the floor the place birds can catch them.
Local weather change threatens the prey these seabirds rely on as a result of the marine creatures are so delicate to altering temperatures, typically shifting northwards and deeper because the ocean warms.
Marlo covers as a lot floor as attainable to maximise his likelihood of catching one thing, looking at evening and utilizing odor to find prey within the darkness. “They don’t flap,” says Ventura. “They surf the wind.”
Weighing not more than a big strawberry, the nightingale manages to cross the Sahara twice a 12 months as a part of a 6,000-mile round-trip between its spring breeding grounds in England and overwintering floor in west Africa.
However their journey is turning into more and more fraught and their vacation spot much less welcoming.
“Berkeley” is a one-year-old nightingale tagged close to Alton Water, a nature reserve just a few miles south of Ipswich within the UK. He was caught on the 31 Might 2023 in a dense patch of bramble and blackthorn, and fitted with a GPS tag the load of a paperclip.
In the course of the summer time Berkeley would have tirelessly gathered beetles, ants, flies and caterpillars to feed his younger. As soon as his household had flown the nest, he was able to migrate south.
Berkeley waited for the proper evening in late August earlier than leaving: gentle, clear and nonetheless. He crossed the Channel and flew down the west coast of France to Spain the place he spent three weeks recuperating and placing on fats earlier than tackling the Atlantic Ocean and Sahara.
Some nightingales could make this crossing in a few days straight; others will cease in the course of the day, resting at a desert oasis in the event that they move one.
Local weather crisis-driven droughts and wildfires in southern Europe, nevertheless, imply extra birds are dying over the Sahara as they’re compelled to proceed their migration with out entering into prime flying situation.
Unhealthy climate can even throw them off track, and they’re hunted by the large noctule bat over the mountains of the Iberian peninsula. Berkeley flew excessive over the desert at about 5,000 metres to remain cool, and managed to dodge all these threats.
On 26 September, 5 weeks after leaving Alton Water, he arrived in Senegal. “Earlier than leaving they need to have a pleasant chunky physique and rounded chest. By the tip, it’s an emaciated factor,” says Chris Hewson, who tracks these birds for the British Belief for Ornithology (BTO).
After a gruelling journey, the overwhelming majority of nightingales winter in Senegal, the Gambia and Guinea-Bissau, however this space has change into more and more threatened because the Sixties as a consequence of extreme droughts, much less rainfall and a much bigger human inhabitants, accumulating firewood and grazing livestock. This has led to irreversible adjustments and diminished the standard of their habitat.
The birds’ habitat in Britain has additionally been very degraded, with elevated numbers of deer, diminished scrub and woodlands. The nightingale inhabitants documented in Britain has fallen by 91% over the previous 50 years, and the lack of appropriate habitat at each ends of their migration is driving that decline.
Understanding precisely the place the birds are by utilizing extra exact GPS tags will assist ecologists do extra targeted conservation work within the areas of highest significance.
Bewick’s swans are one of many heaviest long-distance migratory birds. Their migration of practically 2,200 miles takes a lot vitality they should refuel each few hundred miles.
They have been as soon as depending on aquatic crops however because the Sixties – when agriculture intensified throughout northwestern Europe – they’ve switched to feeding on grass and crops, and might eat all through north-west Europe.
“Mary” was caught and tagged on 20 December 2016 in North Brabant province within the Netherlands. She was a minimum of 4 years previous and caring for a cygnet.
By the next spring, she had launched into a protracted journey north, arriving within the breeding grounds within the distant and wind-swept Malozemelskaya tundra, an space of the Arctic in northern Russia dominated by bogs and wetlands. In September, she set out from the tundra on her autumn migration south, flying to western Latvia, then to Decrease Saxony in northern Germany for the winter.
As Europe warms, Bewick’s swans are making a lot shorter journeys to ice-free wetlands and agricultural areas within the Netherlands, Germany, Denmark and Poland – often called short-stopping. Britain has lost an estimated 43% of its Bewick’s swans in 5 years.
About 60 swans are carrying GPS collars on their necks. Monitoring knowledge reveals that swans modify their autumn journeys each day. On colder days, the birds journey larger distances however whether it is heat, they generally don’t transfer in any respect.
Hans Linssen, a doctoral pupil from the College of Amsterdam, has done modelling on the same birds over several years and confirmed that if winter was 1C (1.8F) colder, the birds would spend it on average 75 miles farther south-west.
Brief-stopping means the birds can adapt their wintering season to a altering local weather. Though it’s a loss for individuals within the Netherlands and the UK – which was the winter capitals for Bewick’s swans – this capacity to adapt to the seasons is prone to be a bonus for the birds.
“In the event that they spend their winter nearer to the breeding vary, the gap that they should go for the subsequent spring can also be shorter, which additionally allows them emigrate sooner,” says Linssen.
The Bewick’s swan inhabitants is quickly declining, however this might need extra to do with unlawful looking than local weather change, says Linssen. As much as a 3rd of Bewick’s swans within the UK have lead pellets from shotgun shells or fishing weights embedded of their our bodies.
Different potential pressures embrace competitors with different species reminiscent of whooper and mute swans on spring migration stopovers, and predation of eggs and hatchlings within the Arctic as predators reminiscent of crimson foxes shift farther north.
Illustrations by Tina Zellmer, graphics by Heidi Wilson and Harvey Symons
Discover extra age of extinction coverage here, and comply with the biodiversity reporters Phoebe Weston and Patrick Greenfield within the Guardian app for extra nature protection
Methodology
International temperature knowledge got here from CHELSA’s every day imply air temperatures measured from hourly ERA5 knowledge, spanning from 1981 to 2010. International vegetation knowledge got here from Nasa’s Terra/Modis month-to-month vegetation index, NDVI 2024. The world map borders, reduction, and land-use colors are from Natural Earth.
For the flight paths within the Americas, we used the migrations of 30 of the 118 species tracked in this study. European flight-path tracks have been from this 2016 GPS tracking dataset in northern and japanese Europe.
Desertas petrel migratory flight paths were part of this study, whereas the detailed hurricane-hunting flight path was plotted from knowledge offered by Francesco Ventura and his colleagues. Wind and velocity route knowledge was taken from the Copernicus ERA5 dataset, and the hurricane monitor comes from NOAA. The audio was recorded by Ben Metzger.
The nightingale’s journey was constructed from the GPS monitoring of two birds in 2023. The tracks and suitability map knowledge was equipped by the BTO’s Chris Hewson and Máire Kirkland from their study on migratory connectivity. The audio was recorded by Grzegorz Michalski.
The Bewick’s swans’ migratory paths have been offered by Hans Linssen and utilized in this study on how migratory swans modify to a warming local weather. The audio was recorded by David Darrell-Lambert.
With because of Joanne Morten from BirdLife Worldwide for her steerage on seabird migration knowledge and paths, and to Jon Carter from the BTO for sourcing data in the beginning of the challenge.
Chook information in regards to the nightingale and Bewick’s swans got here from the RSPB; details about the Desertas petrel was from the Madeira birds website.
Citations:
Climatologies at high resolution for the Earth land surface areas
DN Karger; O Conrad; J Böhner; T Kawohl; H Kreft; RW Soria-Auza; NE Zimmermann; P Linder; M Kessler; 2017
Convergence of broad-scale migration strategies in terrestrial birds
FA La Sorte; D Fink; WM Hochachka; and S Kelling; 2016
GPS tracking of Storks, Cranes and birds of prey, breeding in Northern and Eastern Europe
Okay Adojaan; U Sellis; Ü Väli; I Ojaste; Okay Denac; A Lõhmus; J Ķuze; BirdMap Knowledge – GPS monitoring of Storks, Cranes and birds of prey, breeding in Northern and Jap Europe. Knowledge accessed by way of GBIF.org
Oceanic seabirds chase tropical cyclones
Francesco Ventura; Neele Sander; Paulo Catry; Ewan Wakefield; Federico De Pascalis; Philip L Richardson; José Pedro Granadeiro; Mónica C Silva; Caroline C Ummenhofer; 2024
Extreme migratory connectivity and apparent mirroring of non-breeding grounds conditions in a severely declining breeding population of an afro-palearctic migratory bird
Máire Kirkland; Nathaniel ND Annorbah; Lee Barber; John Black; Jeremy Blackburn; Michael Colley; Gary Clewley; Colin Cross; Mike Drew; Oliver JL Fox; Vicky Gilson; Steffen Hahn; Chas Holt; Mark F Hulme; John Jarjou; Dembo Jatta; Emmanuel Jatta; Kevin Leighton; Ernestina Mensah-Pebi; Chris Orsman; Naffie Sarr; Roger Walsh; Leo Zwarts; Robert J Fuller; Chris M Hewson; 2025
Migratory swans individually adjust their autumn migration and winter range to a warming climate
Hans Linssen; E Emiel van Loon; Judy Z Shamoun-Baranes; Rascha JM Nuijten; Bart A Nolet; 2023
