About storks and migrating birds
-
- Registered user
- Posts: 23861
- Joined: October 19th, 2015, 7:18 pm
Re: About storks and migrating birds
10.3.2020
Observing animal migration from space – ISS experiment ICARUS begins
https://www.dlr.de/content/en/articles/ ... egins.html
(https://www.dlr.de/content/de/artikel/n ... s_iss.html)
Observing animal migration from space – ISS experiment ICARUS begins
https://www.dlr.de/content/en/articles/ ... egins.html
(https://www.dlr.de/content/de/artikel/n ... s_iss.html)
-
- Registered user
- Posts: 274
- Joined: September 14th, 2018, 6:51 pm
cranes, storks and many more on their difficult trip of migration:
https://www.arte.tv/de/videos/066397-000-A/zugvoegel/ in german
https://www.arte.tv/fr/videos/066397-00 ... igrateurs/ in french
https://www.arte.tv/de/videos/066397-000-A/zugvoegel/ in german
https://www.arte.tv/fr/videos/066397-00 ... igrateurs/ in french
-
- Registered user
- Posts: 5948
- Joined: July 25th, 2017, 1:27 pm
Hundreds of thousands of migratory birds have been found dead in New Mexico
" "It's just terrible," Desmond told CNN. "The number is in the six figures. Just by looking at the scope of what we're seeing, we know this is a very large event, hundreds of thousands and maybe even millions of dead birds, and we're looking at the higher end of that."
Dead migratory birds -- which include species such as warblers, bluebirds, sparrows, blackbirds, the western wood pewee and flycatchers -- are also being found in Colorado, Texas and Mexico."
...
"One of the factors biologists believe may have contributed to the deaths of the birds is the wildfires burning in California and other Western states, which may have forced the birds into early migration before they were ready.
...
" "Birds who migrated before they were ready because of the weather might have not had enough fat to survive," Desmond said. "Some birds might have not even had the reserves to start migrating so they died in place." "
...
"Some birds might have had to change their migratory pathways, while others could have inhaled smoke and sustained lung damage.
While the fires and dry weather in New Mexico may have amplified the number of migratory bird deaths, that still leaves many questions."
...
" "We began seeing isolated mortalities in August, so something else has been going on aside the weather events and we don't know what it is. So that in itself is really troubling," she added.
The birds will be sent to the US Fish and Wildlife Service Forensics Laboratory in Oregon for necropsies and to determine their cause of death, but it could take weeks to get results."
https://edition.cnn.com/2020/09/14/us/n ... index.html
" "It's just terrible," Desmond told CNN. "The number is in the six figures. Just by looking at the scope of what we're seeing, we know this is a very large event, hundreds of thousands and maybe even millions of dead birds, and we're looking at the higher end of that."
Dead migratory birds -- which include species such as warblers, bluebirds, sparrows, blackbirds, the western wood pewee and flycatchers -- are also being found in Colorado, Texas and Mexico."
...
"One of the factors biologists believe may have contributed to the deaths of the birds is the wildfires burning in California and other Western states, which may have forced the birds into early migration before they were ready.
...
" "Birds who migrated before they were ready because of the weather might have not had enough fat to survive," Desmond said. "Some birds might have not even had the reserves to start migrating so they died in place." "
...
"Some birds might have had to change their migratory pathways, while others could have inhaled smoke and sustained lung damage.
While the fires and dry weather in New Mexico may have amplified the number of migratory bird deaths, that still leaves many questions."
...
" "We began seeing isolated mortalities in August, so something else has been going on aside the weather events and we don't know what it is. So that in itself is really troubling," she added.
The birds will be sent to the US Fish and Wildlife Service Forensics Laboratory in Oregon for necropsies and to determine their cause of death, but it could take weeks to get results."
https://edition.cnn.com/2020/09/14/us/n ... index.html
-
- Registered user
- Posts: 23861
- Joined: October 19th, 2015, 7:18 pm
September 21
Hello everyone
The data behind mysterious bird deaths in New Mexico - https://www.aba.org/the-data-behind-mys ... ew-mexico/
... these birds were starved and succumbed to hypothermia ...
Hello everyone
balistar,balistar wrote: ↑September 15th, 2020, 2:08 pm Hundreds of thousands of migratory birds have been found dead in New Mexico
https://edition.cnn.com/2020/09/14/us/n ... index.html
The data behind mysterious bird deaths in New Mexico - https://www.aba.org/the-data-behind-mys ... ew-mexico/
... these birds were starved and succumbed to hypothermia ...
-
- Registered user
- Posts: 5948
- Joined: July 25th, 2017, 1:27 pm
It's just so sad....Solo wrote: ↑September 21st, 2020, 3:44 pm September 21
Hello everyone
balistar,
The data behind mysterious bird deaths in New Mexico - https://www.aba.org/the-data-behind-mys ... ew-mexico/
... these birds were starved and succumbed to hypothermia ...
Thank you, Solo.
-
- Registered user
- Posts: 23861
- Joined: October 19th, 2015, 7:18 pm
September 23
Hello everyone
Project Icarus
Zugvögel unter Beobachtung aus dem Weltraum https://www.sueddeutsche.de/wissen/zugv ... -1.5041128
Hello everyone
Project Icarus
Zugvögel unter Beobachtung aus dem Weltraum https://www.sueddeutsche.de/wissen/zugv ... -1.5041128
- sova
- Registered user
- Posts: 30804
- Joined: October 14th, 2015, 7:11 pm
https://www.bz-berlin.de/panorama/57-st ... uomRptiPAQ
Flown 57 hours for free! Migratory bird turns around because of bad weather
Due to adverse weather conditions, a common godwit turned around on its way to New Zealand and flew thousands of kilometers back to Alaska. The animal, whose migration is being followed by the New Zealand Department of Conservation on its leg using a radio transmitter, started in the Yukon-Kuskokwim Delta in Alaska towards the South Pacific, the agency said on Monday.
After 2000 kilometers, however, the adult bird encountered such strong winds that it had to turn around. After a 57-hour non-stop flight, he landed back in Alaska.
The behavior is very unusual for a woodcock (Limosa lapponica) - called "Kuaka" in New Zealand - said zoology professor Phil Battley from Massey University in New Zealand. "Over the years we've tracked about 70 bogwarts that left Alaska, and this is the first we know of had to turn back due to bad weather." Other specimens that left Alaska around the same time would have it Made it to New Zealand.
Headwind? Probably not a good start
Researchers are particularly interested in what the bird will do next, how long it will rest and whether it will still make it all the way to New Zealand, according to Battley. “He still has time. He has certainly not used up all his energy, ”said the expert. "He noticed that he was facing a headwind and thought it was not a good start for a ten-day flight."
The same snipe had to struggle with strong winds last year and ended up in New Caledonia in the South Seas for a month.
"Anyone who's struggled with the same problem for two years in a row can be said to be unlucky," said Battley.
The 11,000-kilometer non-stop migration of the common woodcock is one of the longest in the bird world.
Flown 57 hours for free! Migratory bird turns around because of bad weather
Due to adverse weather conditions, a common godwit turned around on its way to New Zealand and flew thousands of kilometers back to Alaska. The animal, whose migration is being followed by the New Zealand Department of Conservation on its leg using a radio transmitter, started in the Yukon-Kuskokwim Delta in Alaska towards the South Pacific, the agency said on Monday.
After 2000 kilometers, however, the adult bird encountered such strong winds that it had to turn around. After a 57-hour non-stop flight, he landed back in Alaska.
The behavior is very unusual for a woodcock (Limosa lapponica) - called "Kuaka" in New Zealand - said zoology professor Phil Battley from Massey University in New Zealand. "Over the years we've tracked about 70 bogwarts that left Alaska, and this is the first we know of had to turn back due to bad weather." Other specimens that left Alaska around the same time would have it Made it to New Zealand.
Headwind? Probably not a good start
Researchers are particularly interested in what the bird will do next, how long it will rest and whether it will still make it all the way to New Zealand, according to Battley. “He still has time. He has certainly not used up all his energy, ”said the expert. "He noticed that he was facing a headwind and thought it was not a good start for a ten-day flight."
The same snipe had to struggle with strong winds last year and ended up in New Caledonia in the South Seas for a month.
"Anyone who's struggled with the same problem for two years in a row can be said to be unlucky," said Battley.
The 11,000-kilometer non-stop migration of the common woodcock is one of the longest in the bird world.
-
- Registered user
- Posts: 23861
- Joined: October 19th, 2015, 7:18 pm
-
- Registered user
- Posts: 2752
- Joined: March 15th, 2019, 4:20 pm
- Location: Langweid am Lech, Southern Germany
Hello everybody!
Found this on YouTube: BirdLife South Africa Channel
https://www.youtube.com/watch?v=srsue154UaE
VABF Patrik Byholm European Honey Buzzards F2 2021
Quote:" Dr Patrik Byholm will present the recent findings from a longitudinal study on the migration ecology of European honey buzzards (Pernis apivorus). I will focus on explaining how young naive migrants learn the migration secrets and how they develop as they age. I will also discuss the conservation challenges long-distance migrants are confronted with, with illuminating examples from our GPS-tracking work."
Sadly, CABS (Committee Against Bird Slaughter) posted this yesterday (Oct 11):
https://twitter.com/CABS_REPORTS
"After travelling thousands of km on migration to sub-Saharan Africa.. how desperately sad that people think it’s ‘cool’ to blast & butcher a #HoneyBuzzard from the sky & post it online as a brag? Stricter enforcement is urgently needed to stop these incidents in #Lebanon. "
Found this on YouTube: BirdLife South Africa Channel
https://www.youtube.com/watch?v=srsue154UaE
VABF Patrik Byholm European Honey Buzzards F2 2021
Quote:" Dr Patrik Byholm will present the recent findings from a longitudinal study on the migration ecology of European honey buzzards (Pernis apivorus). I will focus on explaining how young naive migrants learn the migration secrets and how they develop as they age. I will also discuss the conservation challenges long-distance migrants are confronted with, with illuminating examples from our GPS-tracking work."
Sadly, CABS (Committee Against Bird Slaughter) posted this yesterday (Oct 11):
https://twitter.com/CABS_REPORTS
"After travelling thousands of km on migration to sub-Saharan Africa.. how desperately sad that people think it’s ‘cool’ to blast & butcher a #HoneyBuzzard from the sky & post it online as a brag? Stricter enforcement is urgently needed to stop these incidents in #Lebanon. "
- Liz01
- Registered user
- Posts: 77490
- Joined: January 21st, 2014, 2:06 pm
- Location: Germany
The impact of the Russian invasion of Ukraine on wild birds and their habitats
On February 24, 2022, Russia invaded the territory of Ukraine. This threatened not only Ukraine's population but also biodiversity, including a significant number of rare and globally vulnerable bird species
On February 24, 2022, Russia invaded the territory of Ukraine. This threatened not only Ukraine's population but also biodiversity, including a significant number of rare and globally vulnerable bird species
https://www.birdlife.org/news/2022/08/2 ... -habitats/Large land areas of natural and agricultural landscapes are covered by numerous deep funnels from aircraft bombs, missiles and artillery shells. This destroys the habitat for birds (e.g. Grey Partridge, Skylark, Short-eared Owl and Montague’s Harrier) as well as other biodiversity.
On wetlands, in particular in the Dnieper and Desna rivers basins, there is a disruption (in some cases significant) of the hydrological regime due to the destruction of hydraulic structures and bridges. This will reduce the area of habitats for wetland birds.
As a result of bombings and rocket attacks, there have been large-scale forest fires (Chornobyl zone) and fires in the reed thickets in river floodplains (Azov-Black Sea region) destroying the habitats of forest bird species (e.g. Black Stork, Black Kite, Short-toed Eagle, Lesser Spotted, Black Grouse, Capercaillie, Eagle Owl, Great Grey, and Common Crane) and wetland species (e.g. Great White, Bittern, Spoonbill, Glossy Ibis, Purpe Heron, Shoveler, Gadwall, Pochard).
-
- Registered user
- Posts: 2752
- Joined: March 15th, 2019, 4:20 pm
- Location: Langweid am Lech, Southern Germany
I wonder if this may turn out to be a general situation regarding migrating birds in Europe. Reasons yet to be assessed! - I follow the Batumi Raptor Count which is situated in Georgia (Black Sea, at the right), whereas 'our' birds mostly take the flyway via Burgas, Bulgaria (Black Sea, at the left).
I would like to quote a tweet by Wouter Vansteelant (co-founder of BRC and currently on site):
"In 14 yrs of @BatumiRaptors we've never seen delayed migration across such a wide range of species, from harriers and kites to Booted Eagles and Honey Buzzards. On top of that we just had 4 days of rain. Perfect recipe for absolute raptor mayhem when the dam breaks tmrw. "
https://twitter.com/WMGVs/status/156758 ... v1lsErAAAA
I would like to quote a tweet by Wouter Vansteelant (co-founder of BRC and currently on site):
"In 14 yrs of @BatumiRaptors we've never seen delayed migration across such a wide range of species, from harriers and kites to Booted Eagles and Honey Buzzards. On top of that we just had 4 days of rain. Perfect recipe for absolute raptor mayhem when the dam breaks tmrw. "
https://twitter.com/WMGVs/status/156758 ... v1lsErAAAA
-
- Registered user
- Posts: 2752
- Joined: March 15th, 2019, 4:20 pm
- Location: Langweid am Lech, Southern Germany
Bird migration is clearly delayed this season, they are 'behind schedule' for at least a week. See for example the latest migration count data at Batumi, very interesting and, of course, yet to be assessed and evaluated:
https://twitter.com/BatumiRaptors/statu ... 1479842816
By the way: Yesterday they counted every species.
https://www.batumiraptorcount.org/data
Hooray for LSEs, more than 700 in sum, a remarkable stream! And Black Storks: Sakhalvasho- 284. Shuamta - 114.
https://twitter.com/BatumiRaptors/statu ... 1479842816
By the way: Yesterday they counted every species.
https://www.batumiraptorcount.org/data
Hooray for LSEs, more than 700 in sum, a remarkable stream! And Black Storks: Sakhalvasho- 284. Shuamta - 114.
-
- Registered user
- Posts: 450
- Joined: July 6th, 2019, 8:58 pm
Remarkable record:
BBC News - Osprey chick migrates 4,000 miles from Scotland to Barbados
https://www.bbc.co.uk/news/uk-scotland-65089646
BBC News - Osprey chick migrates 4,000 miles from Scotland to Barbados
https://www.bbc.co.uk/news/uk-scotland-65089646
- Liz01
- Registered user
- Posts: 77490
- Joined: January 21st, 2014, 2:06 pm
- Location: Germany
Pilot project in the Netherlands
Wind turbines stopped to protect migratory birds
Status: 05/16/2023 10:49 a.m
The rapid expansion of wind power is increasingly threatening the lives of migratory birds. The Netherlands has now temporarily switched off the turbines of wind farms to allow the animals to pass safely. To protect millions of migratory birds, the Netherlands have stopped wind turbines in their wind farms off the coast for the first time. On Saturday, the offshore wind turbines in Borssele and Egmond aan Zee were shut down for four hours because massive bird migration had been predicted over the North Sea, the government said. "This is an international premiere," said the government Dutch Energy Minister Rob Jetten. Nowhere else in the world would wind farms in the sea be switched off to protect the birds. The government wants to keep the impact of wind farms on nature as low as possible. From this autumn, the wind farms are expected to be switched off more frequently after the pilot phase that is now underway, it said. In order to allow birds a safe passage, the wind farm owners should reduce the speed of the wind turbines to a maximum of two revolutions per minute during the predicted nocturnal migration time predicts bird migration two days in advance. This should give the grid operator Tennet time to ensure the stability of the high-voltage grid and to initiate the shutdown of the turbines.
According to the government statement, bird protection expert Tim van Oijen said: "Twice a year, in spring and autumn, millions of birds migrate across the North Sea on some nights." Because of the increasing number of wind farms there, it is extremely important that this expansion has minimal impact on the ecosystem of the North Sea. Growing danger from wind farms in Germany too. In Germany, too, the planned strong expansion of wind energy on the North Sea and Baltic Sea represents an increasing danger for migratory birds, according to biologists. There are currently 22 wind farms in the North Sea and three in the Baltic Sea off the German coast, with a total capacity of 8 .1 gigawatts. By 2030 it should be 30 gigawatts, by 2045 the total output should be increased to at least 70 gigawatts according to the offshore wind energy law that came into force at the beginning of the year.
https://www.tagesschau.de/ausland/europ ... z-100.html
Wind turbines stopped to protect migratory birds
Status: 05/16/2023 10:49 a.m
The rapid expansion of wind power is increasingly threatening the lives of migratory birds. The Netherlands has now temporarily switched off the turbines of wind farms to allow the animals to pass safely. To protect millions of migratory birds, the Netherlands have stopped wind turbines in their wind farms off the coast for the first time. On Saturday, the offshore wind turbines in Borssele and Egmond aan Zee were shut down for four hours because massive bird migration had been predicted over the North Sea, the government said. "This is an international premiere," said the government Dutch Energy Minister Rob Jetten. Nowhere else in the world would wind farms in the sea be switched off to protect the birds. The government wants to keep the impact of wind farms on nature as low as possible. From this autumn, the wind farms are expected to be switched off more frequently after the pilot phase that is now underway, it said. In order to allow birds a safe passage, the wind farm owners should reduce the speed of the wind turbines to a maximum of two revolutions per minute during the predicted nocturnal migration time predicts bird migration two days in advance. This should give the grid operator Tennet time to ensure the stability of the high-voltage grid and to initiate the shutdown of the turbines.
According to the government statement, bird protection expert Tim van Oijen said: "Twice a year, in spring and autumn, millions of birds migrate across the North Sea on some nights." Because of the increasing number of wind farms there, it is extremely important that this expansion has minimal impact on the ecosystem of the North Sea. Growing danger from wind farms in Germany too. In Germany, too, the planned strong expansion of wind energy on the North Sea and Baltic Sea represents an increasing danger for migratory birds, according to biologists. There are currently 22 wind farms in the North Sea and three in the Baltic Sea off the German coast, with a total capacity of 8 .1 gigawatts. By 2030 it should be 30 gigawatts, by 2045 the total output should be increased to at least 70 gigawatts according to the offshore wind energy law that came into force at the beginning of the year.
https://www.tagesschau.de/ausland/europ ... z-100.html
- Liz01
- Registered user
- Posts: 77490
- Joined: January 21st, 2014, 2:06 pm
- Location: Germany
thank you Shai Blitzblau for letting me know!
Migrating shorebird killed by raptor at 3000 m above ground as revealed by high-resolution tracking
Michiel P. Boom, Hui Yu, Roeland A. Bom, Arne Hegemann, Åke Lindström, Bart A. Nolet, Thomas K. Lameris
First published: 07 October 2024 https://doi.org/10.1002/ecy.4437
Recent tracking technology has revealed that some birds fly at extreme altitudes up to and above 7000 m above sea level (asl) during nonstop migration flights (Lindström et al., 2021; Sjöberg et al., 2021). An untested hypothesis put forward is that birds migrate this high above the ground to avoid encountering predators. However, information about predation danger during the migratory flight is scant, and the altitudes where migrants are at risk are unknown.
While migration enables animals to exploit favorable habitat conditions in various locations throughout the year to optimize overall fitness (Lack, 1968), it can also be costly and is often associated with higher mortality rates (Klaassen et al., 2014). A significant factor contributing to these high mortality rates is the increased risk of predation during migration (Lindström, 1989; Sillett & Holmes, 2002; Walter, 1979). Consequently, safety is considered an important evolutionary driver of avian migration strategies (Alerstam et al., 2003; Alerstam & Lindström, 1990; Lank et al., 2003; Ydenberg et al., 2004).
In birds, predation has mostly been studied at migratory stopover sites (Dierschke, 2003; Lindström, 1989), but information about predation risk during the migratory flight is largely lacking, especially concerning at what altitudes migrants are at risk. It was recently revealed that during long nonstop flights, some migrants ascend at dawn to diurnal flight altitudes up to and above 7000 m asl (Lindström et al., 2021; Sjöberg et al., 2021). These studies propose that the birds try to avoid being predated by flying very high above the ground. Eleonora's Falcons Falco eleonorae, which specialize in hunting migratory passerines, have been recorded to make flights up to 3500 m (Xirouchakis & Panuccio, 2019), but the knowledge on how high avian predators ascend to hunt is very limited.
Using GPS trackers with on-board accelerometry, we tracked Arctic-breeding Grey Plovers Pluvialis squatarola (Figure 1a,b) migrating across Northern Europe. In January 2023, we tagged eight adult Grey Plovers with Druid MINI 2G transmitters on the island of Griend (53°15′ N, 5°15′ E) in the Dutch Wadden Sea. Tags were attached using leg-loop harnesses constructed from flattened spectra ribbon (2.5 mm width) and aluminum crimps (combined mass of transmitter and harness <8 g, equaling <5% of body mass). The solar-powered transmitters record GPS positions (including altitude), and ODBA (overall dynamic body acceleration, a measure for activity (Wilson et al., 2006), hereafter “body acceleration” for short). Data were transferred via the 2G GSM network. Interval settings varied from 2 to 24 h for GPS positions and 1–30 min for body acceleration measurements. The onboard tri-axial accelerometer sampled data continuously at 25 Hz which were summarized into one body acceleration value every 10 s following Wilson et al. (2006). These values were then used to calculate average body acceleration values based on the set interval (e.g., mean of 6 values for 1-min body acceleration setting).
FIGURE 1
(a, b) 11:21 25-01-2023, Griend, The Netherlands. The Grey Plover photographed upon release on the island of Griend in the Dutch Wadden Sea in January 2023, equipped with color bands (a) and a Druid MINI 2G transmitter (b). (c) 12:17 04-06-2023, Lund municipality, Sweden. The transmitter and several of the colors bands found next to the remains of the Grey Plover near the Peregrine Falcon nest in Southern Sweden in June 2023. Photographs: Thomas K. Lameris (a, b), Arne Hegemann (c).
At 21:58 local summer time on May 27 (25 min after sunset), one of the tagged birds suddenly stopped its migratory flight (Figure 2a,b). At the same moment, the body acceleration signal (1-min average) of the tracking device on this plover made a steep drop from 1.45 to 0.27 g (Figure 2c). Two minutes later (i.e., 22:00), the logger recorded a GPS fix at an altitude of 2882 m above ground (about 2900 m asl). Additional information from this fix was in strong contrast with the previous fixes: a change in course from 64° (NE) to 194° (SW) and a decrease in speed of flight from 14.4 ± 4.1 m/s to 6.4 m/s (Figure 2c). The subsequent GPS fix at 00:00 h on May 28 and all subsequent fixes came from a single position 8 km away.
FIGURE 2
Spring migration routes (a) and flight altitude (b) of four Grey Plovers tracked across Northern Europe by GPS-GSM transmitters with 2-h sampling interval (except one individual with 24-h interval). The track of the predated plover is highlighted in red, and the predation location is marked by a cross. Positions above land are marked with dots, positions above sea are marked with diamonds. (c) Overall dynamic body acceleration of the predated individual during the 5 h prior to predation, including an inset of the last 30 min. Information from three GPS fixes of the predated individual is annotated in the bottom of the graph, including flight altitude (gray bars), flight course (direction of arrows), and flight speed (in meters per second). Illustrations: Thomas K. Lameris.
Here, the tag and remains of the bird (Figure 1c) were found within 200 m of a peregrine nest, undoubtingly suggesting predation by a peregrine falcon (Falco peregrinus) as the cause of death. Together this suggests that the plover was captured by the falcon at 21:58. Considering the 2-min delay of GPS fix after the predation, the predation altitude was at least 2882 m above ground level (Figure 2c) but could have been higher. In the 15 min right before the predation event (21:43–21:58), the plover displayed increased body acceleration (1.44 ± 0.07 g, Figure 1c), which was significantly higher than the previous 15-min period body acceleration (1.26 ± 0.04 g, t(22) = −8.6, p < 0.0001). Increased body acceleration is associated with increased flight intensity (Krishnan et al., 2022), which could indicate that the plover spotted the predator peregrine falcon at around 21:43 and made an attempt to escape.
Peregrines use various hunting techniques to capture birds in flight (Zoratto et al., 2010), including a characteristic surprise stoop dive from above, which requires the peregrine to ascent to higher altitudes than its prey to hunt. In the case of the observed predation event, the potential attempt to escape (based on the observed 15-min increase in dynamic body acceleration) of the Grey Plover suggests that the peregrine would have used a pursuit tactic, which is also commonly observed (Dekker, 2009; Zoratto et al., 2010).
We also compared migration timing and flight altitude of the predated individual with three other tracked individuals from which we received data for the period from departure from the Wadden Sea and up to passage into the Russian Arctic (37° E). The route taken by the predated plover was similar to that of the other tracked individual plovers (Figure 2a). The predated plover started its migratory flight on May 26, which was also comparable with the other three tracked individuals (May 26–28). All four plovers flew higher above land (mean flight altitude 1726 ± 966 m, Figure 2b) than above sea (302 ± 717 m, Figure 2b). The altitude at which the predated plover was captured (2882 m) was at the higher end of the altitudinal range of flight over land (0–3216 m) in our dataset.
Although in-flight predation of birds in active migration is indirectly documented through the large numbers of migratory prey species in the diet of falcons (Xirouchakis et al., 2019; Zuberogoitia et al., 2013), direct evidence is limited to ground-based observations, by necessity limiting the altitudes at which predation events can be recorded (Rudebeck, 1950, 1951). This limitation is lifted by the recent application of ever lighter high-resolution tracking devices on small-bodied birds, enabling us to remotely record in-flight predation (e.g., Bom et al., 2023). The observed predation event constitutes an exceptional record of high-altitude hunting by Peregrine Falcons. These falcons are specialized in hunting birds and capturing them in flight (Xirouchakis et al., 2019; Zuberogoitia et al., 2013). During migratory flight, Peregrine Falcons can reach altitudes up to 5600 m (Dixon et al., 2017), but up to which altitude they hunt is unclear. GPS-tracking of Greater Noctule Bats Nyctalus lasiopterus, known to prey on migratory birds (Ibáñez et al., 2001), has unveiled they forage up to 1659 m above ground level (Naďo et al., 2019). In areas and periods with sufficient prey availability at high altitude (e.g., migration corridors during shorebird migration), hunting at high altitudes may be a profitable strategy.
While predation risk is considered an important evolutionary driver of migration strategies (Alerstam & Lindström, 1990; Lank et al., 2003; Ydenberg et al., 2004), its role in shaping flight altitudes remains only speculative. The application of high-resolution tracking now makes it possible to address questions on where, when, and up to which altitude birds risk predation during migratory flight, and for example whether flying at extreme altitudes during the day may be a successful adaptive strategy to avoid predators. Our observation suggests that this may not always be the case, as increasing flight altitude up to 3000 m above ground is clearly not enough for migrants to avoid predation risk.
https://esajournals.onlinelibrary.wiley ... 2/ecy.4437
Migrating shorebird killed by raptor at 3000 m above ground as revealed by high-resolution tracking
Michiel P. Boom, Hui Yu, Roeland A. Bom, Arne Hegemann, Åke Lindström, Bart A. Nolet, Thomas K. Lameris
First published: 07 October 2024 https://doi.org/10.1002/ecy.4437
Recent tracking technology has revealed that some birds fly at extreme altitudes up to and above 7000 m above sea level (asl) during nonstop migration flights (Lindström et al., 2021; Sjöberg et al., 2021). An untested hypothesis put forward is that birds migrate this high above the ground to avoid encountering predators. However, information about predation danger during the migratory flight is scant, and the altitudes where migrants are at risk are unknown.
While migration enables animals to exploit favorable habitat conditions in various locations throughout the year to optimize overall fitness (Lack, 1968), it can also be costly and is often associated with higher mortality rates (Klaassen et al., 2014). A significant factor contributing to these high mortality rates is the increased risk of predation during migration (Lindström, 1989; Sillett & Holmes, 2002; Walter, 1979). Consequently, safety is considered an important evolutionary driver of avian migration strategies (Alerstam et al., 2003; Alerstam & Lindström, 1990; Lank et al., 2003; Ydenberg et al., 2004).
In birds, predation has mostly been studied at migratory stopover sites (Dierschke, 2003; Lindström, 1989), but information about predation risk during the migratory flight is largely lacking, especially concerning at what altitudes migrants are at risk. It was recently revealed that during long nonstop flights, some migrants ascend at dawn to diurnal flight altitudes up to and above 7000 m asl (Lindström et al., 2021; Sjöberg et al., 2021). These studies propose that the birds try to avoid being predated by flying very high above the ground. Eleonora's Falcons Falco eleonorae, which specialize in hunting migratory passerines, have been recorded to make flights up to 3500 m (Xirouchakis & Panuccio, 2019), but the knowledge on how high avian predators ascend to hunt is very limited.
Using GPS trackers with on-board accelerometry, we tracked Arctic-breeding Grey Plovers Pluvialis squatarola (Figure 1a,b) migrating across Northern Europe. In January 2023, we tagged eight adult Grey Plovers with Druid MINI 2G transmitters on the island of Griend (53°15′ N, 5°15′ E) in the Dutch Wadden Sea. Tags were attached using leg-loop harnesses constructed from flattened spectra ribbon (2.5 mm width) and aluminum crimps (combined mass of transmitter and harness <8 g, equaling <5% of body mass). The solar-powered transmitters record GPS positions (including altitude), and ODBA (overall dynamic body acceleration, a measure for activity (Wilson et al., 2006), hereafter “body acceleration” for short). Data were transferred via the 2G GSM network. Interval settings varied from 2 to 24 h for GPS positions and 1–30 min for body acceleration measurements. The onboard tri-axial accelerometer sampled data continuously at 25 Hz which were summarized into one body acceleration value every 10 s following Wilson et al. (2006). These values were then used to calculate average body acceleration values based on the set interval (e.g., mean of 6 values for 1-min body acceleration setting).
FIGURE 1
(a, b) 11:21 25-01-2023, Griend, The Netherlands. The Grey Plover photographed upon release on the island of Griend in the Dutch Wadden Sea in January 2023, equipped with color bands (a) and a Druid MINI 2G transmitter (b). (c) 12:17 04-06-2023, Lund municipality, Sweden. The transmitter and several of the colors bands found next to the remains of the Grey Plover near the Peregrine Falcon nest in Southern Sweden in June 2023. Photographs: Thomas K. Lameris (a, b), Arne Hegemann (c).
At 21:58 local summer time on May 27 (25 min after sunset), one of the tagged birds suddenly stopped its migratory flight (Figure 2a,b). At the same moment, the body acceleration signal (1-min average) of the tracking device on this plover made a steep drop from 1.45 to 0.27 g (Figure 2c). Two minutes later (i.e., 22:00), the logger recorded a GPS fix at an altitude of 2882 m above ground (about 2900 m asl). Additional information from this fix was in strong contrast with the previous fixes: a change in course from 64° (NE) to 194° (SW) and a decrease in speed of flight from 14.4 ± 4.1 m/s to 6.4 m/s (Figure 2c). The subsequent GPS fix at 00:00 h on May 28 and all subsequent fixes came from a single position 8 km away.
FIGURE 2
Spring migration routes (a) and flight altitude (b) of four Grey Plovers tracked across Northern Europe by GPS-GSM transmitters with 2-h sampling interval (except one individual with 24-h interval). The track of the predated plover is highlighted in red, and the predation location is marked by a cross. Positions above land are marked with dots, positions above sea are marked with diamonds. (c) Overall dynamic body acceleration of the predated individual during the 5 h prior to predation, including an inset of the last 30 min. Information from three GPS fixes of the predated individual is annotated in the bottom of the graph, including flight altitude (gray bars), flight course (direction of arrows), and flight speed (in meters per second). Illustrations: Thomas K. Lameris.
Here, the tag and remains of the bird (Figure 1c) were found within 200 m of a peregrine nest, undoubtingly suggesting predation by a peregrine falcon (Falco peregrinus) as the cause of death. Together this suggests that the plover was captured by the falcon at 21:58. Considering the 2-min delay of GPS fix after the predation, the predation altitude was at least 2882 m above ground level (Figure 2c) but could have been higher. In the 15 min right before the predation event (21:43–21:58), the plover displayed increased body acceleration (1.44 ± 0.07 g, Figure 1c), which was significantly higher than the previous 15-min period body acceleration (1.26 ± 0.04 g, t(22) = −8.6, p < 0.0001). Increased body acceleration is associated with increased flight intensity (Krishnan et al., 2022), which could indicate that the plover spotted the predator peregrine falcon at around 21:43 and made an attempt to escape.
Peregrines use various hunting techniques to capture birds in flight (Zoratto et al., 2010), including a characteristic surprise stoop dive from above, which requires the peregrine to ascent to higher altitudes than its prey to hunt. In the case of the observed predation event, the potential attempt to escape (based on the observed 15-min increase in dynamic body acceleration) of the Grey Plover suggests that the peregrine would have used a pursuit tactic, which is also commonly observed (Dekker, 2009; Zoratto et al., 2010).
We also compared migration timing and flight altitude of the predated individual with three other tracked individuals from which we received data for the period from departure from the Wadden Sea and up to passage into the Russian Arctic (37° E). The route taken by the predated plover was similar to that of the other tracked individual plovers (Figure 2a). The predated plover started its migratory flight on May 26, which was also comparable with the other three tracked individuals (May 26–28). All four plovers flew higher above land (mean flight altitude 1726 ± 966 m, Figure 2b) than above sea (302 ± 717 m, Figure 2b). The altitude at which the predated plover was captured (2882 m) was at the higher end of the altitudinal range of flight over land (0–3216 m) in our dataset.
Although in-flight predation of birds in active migration is indirectly documented through the large numbers of migratory prey species in the diet of falcons (Xirouchakis et al., 2019; Zuberogoitia et al., 2013), direct evidence is limited to ground-based observations, by necessity limiting the altitudes at which predation events can be recorded (Rudebeck, 1950, 1951). This limitation is lifted by the recent application of ever lighter high-resolution tracking devices on small-bodied birds, enabling us to remotely record in-flight predation (e.g., Bom et al., 2023). The observed predation event constitutes an exceptional record of high-altitude hunting by Peregrine Falcons. These falcons are specialized in hunting birds and capturing them in flight (Xirouchakis et al., 2019; Zuberogoitia et al., 2013). During migratory flight, Peregrine Falcons can reach altitudes up to 5600 m (Dixon et al., 2017), but up to which altitude they hunt is unclear. GPS-tracking of Greater Noctule Bats Nyctalus lasiopterus, known to prey on migratory birds (Ibáñez et al., 2001), has unveiled they forage up to 1659 m above ground level (Naďo et al., 2019). In areas and periods with sufficient prey availability at high altitude (e.g., migration corridors during shorebird migration), hunting at high altitudes may be a profitable strategy.
While predation risk is considered an important evolutionary driver of migration strategies (Alerstam & Lindström, 1990; Lank et al., 2003; Ydenberg et al., 2004), its role in shaping flight altitudes remains only speculative. The application of high-resolution tracking now makes it possible to address questions on where, when, and up to which altitude birds risk predation during migratory flight, and for example whether flying at extreme altitudes during the day may be a successful adaptive strategy to avoid predators. Our observation suggests that this may not always be the case, as increasing flight altitude up to 3000 m above ground is clearly not enough for migrants to avoid predation risk.
https://esajournals.onlinelibrary.wiley ... 2/ecy.4437