This question just popped into my head after reading a physics problem. 30,000ft is just a rough number. What about even higher?
Could a bird fly to the ground safely after being dumped from a 30,000 ft (or higher) elevation?
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Zenmervolt
Elite member
- Oct 22, 2000
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I have a friend who is a very experienced naturalist, give me a day or two and I'll have an answer for you. (I'm quite serious, he'd enjoy the challenge of answering this correctly, and I'm curious myself now.)
Zenmervolt
Zenmervolt
My guess would be that, provided it didn't freeze or die from lack of oxygen and that the air is too thin to create enough lift for it to fly, its wings would get ripped off by the wind once it spread them to fly.
it would depend on the species of bird i think. i don't think a canary or crow would be able to do it, but some predatory birds like hawks and eagles have been known to make dives from high altitudes and reach speeds close to terminal velocity before pulling out of them almost on the ground, so some should survive i would think
Lack of oxygen would kill the bird ...if that did not do it the subzero temp at 30k probably would ... if those 2 things were not enough, the aerodynamic forces experienced by the bird when it opened its wings would probably tear it apart.
Aerodynamic forces tearing the bird apart? No.
Atmospheric density decreases exponentially with altitude. That only affects the terminal velocity, and the maximum force on a streamlined body falling in a constant gravitational field is equal to its weight. The bird however, will never attain that velocity. Upon being "released" at 30,000 ft the bird will lose consciousness within a few seconds (assuming it is a land bird like a pigeon). From then on it will tumble about in the air until it smacks the ground.
But... if it did "dive" and then suddenly spread its wings... well then the wings would snap.
Atmospheric density decreases exponentially with altitude. That only affects the terminal velocity, and the maximum force on a streamlined body falling in a constant gravitational field is equal to its weight. The bird however, will never attain that velocity. Upon being "released" at 30,000 ft the bird will lose consciousness within a few seconds (assuming it is a land bird like a pigeon). From then on it will tumble about in the air until it smacks the ground.
But... if it did "dive" and then suddenly spread its wings... well then the wings would snap.
I believe it was operation xray that the US used over japan in late 1944. They attached small incendiary devices to frozen bats and dropped them out of planes at 30,000 feet. The bats would thaw and come to life on the way down, and carry the bombs to completely random locations. The bombs would detonate and cause widespread fires. However, the bats natural instinct to group togehter foiled the plan. The bombs would detonate in only one or two areas, and not be effective. The plan was discontinued after 3 months of work.
So, yes, I think they could make it if properly prepared.
when a human jumps off an airplane (although not at 30,000 ft), he doesn't get his arms or legs torn off does he? Granted a human has a much stronger skeleton than a bird - but birds are meant to fly, and we are not.
No doubt an eagle, a falcon, or any other streamlined bird would make it.
Ohh, and not all birds need to open their wings to displace their trajectories. My guess is if the bird is smart enough to not open its wings when it reachs terminal velocity, and that at some point it re-directs itself to an increasingly horizontal trajectory, it would slow itself enough to be able to open its wings.
Anyways, what WEIRD question is this???
No doubt an eagle, a falcon, or any other streamlined bird would make it.
Ohh, and not all birds need to open their wings to displace their trajectories. My guess is if the bird is smart enough to not open its wings when it reachs terminal velocity, and that at some point it re-directs itself to an increasingly horizontal trajectory, it would slow itself enough to be able to open its wings.
Anyways, what WEIRD question is this???
Highest-Flying Birds
A Ruppell?s vulture (gyps rueppellii) collided with a commercial aircraft over Abidjan, Ivory Coast, at an altitude of 37,000 feet in November 1973. The impact damaged one of the aircraft?s engines, but the plane landed safely. The species is rarely seen above 20,000 feet.
In 1967, about 30 whooper swans (Cygnus were spotted at an altitude of just over 27,000 feet by an airline pilot over the Western Isles, UK. They were flying from Iceland to Loch Foyle on the Northern Ireland/republic Ireland border. Their altitude was confirmed by air traffic control.
A Ruppell?s vulture (gyps rueppellii) collided with a commercial aircraft over Abidjan, Ivory Coast, at an altitude of 37,000 feet in November 1973. The impact damaged one of the aircraft?s engines, but the plane landed safely. The species is rarely seen above 20,000 feet.
In 1967, about 30 whooper swans (Cygnus were spotted at an altitude of just over 27,000 feet by an airline pilot over the Western Isles, UK. They were flying from Iceland to Loch Foyle on the Northern Ireland/republic Ireland border. Their altitude was confirmed by air traffic control.
Depends on the bird. I think a better question is could an 5 ounce swallow carry a 1 pound coconut?
What if a bird took a dump at 30,000 ft, would the turd droppings kill someone when it falls from that height and landed on his head?
dennilfloss
Past Lifer 1957-2014 In Memoriam
Some relevant facts:
Journal of Physiology (1997), 499.P, 9S
Birds over Mount Everest: extreme hypoxia tolerance
Peter Scheid and Hashim Shams
Institut für Physiologie, Ruhr-Universität Bochum, 44780 Bochum, Germany
Hypoxaemia is a potentially life-threatening situation for mammals. Only few men have succeeded in climbing the summit of Mount Everest, at an altitude of 8848 m, without supplemental oxygen. In contrast, several bird species have been observed to fly at extreme altitudes, the record-holder being a vulture that has collided with an airplane at an altitude of over 11 000 m. The bar-headed goose (Anser indicus) resides in India at sea level and crosses, on its migratory path to the Tibetan highlands, over the Himalayan mountains. How can this extreme hypoxia tolerance of birds be explained?
Birds differ from mammals with respect to the structure of their gas-exchanging organs. Rather than consisting of bronchi and blind-ending alveoli, the lungs of birds consist of long, narrow tubes, the parabronchi, which are open at both ends and are ventilated by the action of a number of wide air sacs. Fine air-filled capillaries leave the parabronchi and intertwine with equally fine blood capillaries for gas exchange. This cross-current system of gas exchange has been shown to have a higher gas exchange efficiency than the alveolar pool system of mammals. The higher efficiency is due to the peculiar arrangement of parabronchial air flow and blood flow in the capillaries, viz. the cross-current flow. Could this be the key for understanding the superiority of birds at high altitude, when oxygen is sparse?
We have performed experiments in the laboratory on the Pekin duck, using a plethysmograph that allowed measurements of respiratory variables in awake, unmolested animals. When lowering the oxygen partial pressure (PO2), the birds increased their ventilation and cardiac output, and arterial PO2 and PCO2 values dropped, qualitatively similar to the situation in man. Without adaptation, the 'lowlander' duck could be brought to an equivalent altitude of over 12 000 m without apparent ill effects.
The most remarkable quantitative result was the extremely low arterial PO2 and PCO2 values at the extreme hypoxic levels. In fact, the inspired arterial differences in these values dropped to below 1 kPa, and the caudal-to-cranial air sac differences approached zero. This meant that ventilation had increased to such a degree that the gas at the gas-blood membrane in the air capillaries had almost the composition of the inspired gas. Under these conditions, the advantage in efficiency of the parabronchial over the alveolar system had disappeared, since the functionally infinite air flow obviously no longer allowed distinction between the cross-current (parabronchial) and pool (alveolar) sytems. Hence the extreme hypoxia tolerance of birds cannot be explained on the basis of differences in the external gas exchange organ.
What else could be the reason for the differences in hypoxia tolerance between mammals and birds? The other members in the gas transport chain are remarkably similar in both vertebrate classes: cardiac output and its increase with hypoxia; oxygen capacity and binding properties of haemoglobin; red cell size, etc. We have very few definite answers to this question yet. It is notable, though, that the flight muscles in particular have a very high capillary and mitochondrial density and a high activity of oxidative enzymes. However, these differences are quantitative at best. One interesting feature is the apparent absence of hypocapnic brain vasoconstriction in birds. This could grant the birds a higher brain blood flow during the respiratory alkalosis at high altitude and might allow the bird a higher ventilation, for the sake of oxygen, with more severe hypocapnia.
---------------------------Another paper from here-----------------------------------------------------------
Migration of Birds
Altitude of Flight Migration
--------------------------------------------------------------------------------
The factors regulating the heights of bird migration are not clear. High-altitude flight may be used to locate familiar landmarks, fly over fog or clouds, surmount physical barriers, gain advantage of a following wind, or maintain a better physiological balance. Meteorological conditions probably account for most of the high-altitude records. Wind conditions at ground level are usually quite different in direction and velocity than at points higher up. In general, human estimates of bird heights are quite unreliable except under special conditions, and these estimates will vary with the eyesight of the observer. Lucanus (1911) found a European sparrow hawk could be distinguished at 800 feet but disappeared from sight at 2,800 feet. A rook (a European member of the crow family) could be recognized at 1,000 feet but disappeared from sight at 3,300 feet. Meinertzhagen (1955) did an interesting experiment with an inflated model of a vulture painted black; it had a wing expanse of 7 feet 10 inches. When released from an airplane at 4,700 feet, it was barely visible and invisible without binoculars at 5,800 feet. At 7,000 feet it was not picked up even when x12 binoculars were used.
At one time students of bird migration believed normal migratory movements took place at heights above 15,000 feet. They reasoned, somewhat uncertainly, that flying became easier as altitude was gained. It has now been shown, through comprehensive radar studies, that 95 percent of the migratory movements occur at less than 10,000 feet, and the bulk of the movements occur under 3,000 feet. However, birds can and do fly well over 15,000 feet without apparent ill effects. The physiology of long-distance flight at high altitudes is of great interest but can only be touched on briefly in this discussion.
Bird flight at 20,000 feet, where less than half the oxygen is present than at sea level, is impressive if only because the work is achieved by living muscle tissue. A Himalayan mountain climber at 16,000 feet was rather amazed when a flock of geese flew north 2 miles over his head honking as they went (Swan 1970). At 20,000 feet a man has a hard time talking and running or other rapid movements are out of the question; but those geese were probably flying at 27,000 feet and even calling while they traveled at this tremendous height.
Accurate observations on the altitude of migratory flights is scanty, although altimeter observations from airplanes and radar are becoming more frequent in the literature. An example is the report of a mallard struck by a commercial airliner at 21,000 feet over the Nevada desert (Manville 1963). It is, of course, obvious that some birds must cross mountain ranges during migration and attain great altitudes. Numerous observations have come from the Himalayas (Geroudet 1954; Swan 1970). Observers at 14,000 feet recorded storks and cranes flying so high that they could be seen only through field glasses. In the same area large vultures were seen soaring at 25,000 feet and an eagle carcass was found at 26,000 feet. The expedition to Mt. Everest in 1952 found skeletons of a pintail and a black-tailed godwit at 16,400 feet on Khumbu Glacier (Geroudet 1954). Bar-headed geese have been observed flying over the highest peaks (29,000+ feet) even though a 10,000-foot pass was nearby. Probably 30 or more species regularly cross these high passes (Swan 1970).
Except to fly over high mountain ranges, birds rarely fly as high as those traveling down the western Atlantic (Richardson 1972). Many of these birds are making long-distance flights to eastern South America and beyond. Therefore, flight at high altitudes in this region is probably advantageous for them. Richardson postulated stronger advantageous tail winds were found higher up and the cooler air minimized evaporative water losses. This investigator found air temperatures averaged 35°F at 10,000 feet over Nova Scotia in September. The lower the ambient temperature, the more heat can be lost by convection and the less water is required for cooling. Also, a bird flying high can achieve the same range as one flying at sea level but must cruise at a higher speed with a corresponding increase in power output and oxygen consumption. But the increased cruising speed results in shorter flight time and less interference from wind (Pennycuick 1969).
Another postulate favoring the high-altitude flying theory was that the wonderful vision of birds was their sole guidance during migratory flights. To keep landmarks in view, birds were obliged to fly high, particularly when crossing wide areas of water. This will be considered in greater detail in the section, "Orientation and Navigation," so here it will be sufficient to say that birds rely only in part upon landmarks to guide them on migration. Also, it must be remembered that definite physical limitations to the range of visibility exist even under perfect atmospheric conditions. Chief of these is the curvature of the earth's surface. Thus, if birds crossing the Gulf of Mexico to Louisiana and Florida flew at a height of 5 miles, they would still be unable to see a third of the way across (during daylight hours). And yet this trip is made twice each year, much of the distance probably at night, by thousands of thrushes, warblers, and others.
The altitude of migration depends upon the species of bird, weather, time of day or year, and geographical features. Nocturnal migrants, studied by radar, appear to fly at different altitudes at different times during the night. Birds generally take off shortly after sundown and rapidly gain maximum altitude. This peak is maintained until around midnight, then the travelers gradually descend until daylight. For most small birds the favored altitude appears to be between 500 and 1,000 feet (Bellrose 1971), but radar studies have found some nocturnal migrants (probably shorebirds) over the ocean were at 15,000 or even 20,000 feet (Lack 1960b; Nisbet 1963b; Richardson 1972). Observations made from lighthouses and other vantage points indicate that certain migrants commonly travel at altitudes of a very few feet to a few hundred feet above sea or land. Sandpipers, northern phalaropes, and various sea ducks have been seen flying so low they were visible only as they topped a wave. Observers stationed at lighthouses and lightships off the English coast have similarly recorded the passage of landbirds flying just above the surface of the water and rarely above 200 feet. During the World Wars, broad areas in the air were under constant surveillance, and many airplane pilots and observers took more than a casual interest in birds. Of the several hundred records resulting from their observations, only 36 were of birds flying above 5,000 feet and only 7 above 8,500 feet. Cranes were once recorded at an altitude of 15,000 feet, while the lapwing was the bird most frequently seen at high levels, 8,500 feet being its greatest recorded altitude. Records of the U.S. Civil Aeronautics Administration show that over two-thirds of all the bird-aircraft collisions occur below 2,000 feet and practically none occur above 6,000 feet (Williams 1950).
Recently, radar has aided greatly in determining differences in the altitude of bird flight. Nocturnal migrants appear to fly slightly higher, on the average, than diurnal migrants, but daytime flights may be influenced more by cloud cover (Lack 1960a; Eastwood and Rider 1965). Bellrose (1971) found little difference in the altitudinal distribution of small nocturnal migrants under clear or overcast skies. Many night migrating birds are killed each year by striking lighthouses, television towers or other man-made illuminated obstructions, but this does not furnish proof that low altitudes are generally used during nocturnal flight because these accidents occur chiefly in foggy weather. Under such conditions, migrating birds seem to be attracted to and confused by lights. Seabirds, such as loons, eiders, and scoters, generally fly very low over the water but gain altitude when land is crossed. The reverse is true for landbirds (Dorst 1963; Bergman and Donner 1964; Eastwood and Rider 1965). There may be a seasonal difference in the altitude of migration, but the evidence is conflicting. Radar echoes studied by Bellrose and Graber in Illinois (1963) showed fall migrants flew higher than spring migrants. They speculated this difference was related to the winds during the fall being more favorable for southerly migration at higher altitudes, while winds at these altitudes in the spring would be less favorable for northerly migration. Eastwood and Rider (1965) studied seasonal migration patterns in England and found the reverse to be true. They suggested one reason for this seasonal difference was that flocks of fall migrants included many young birds whose flight capabilities are inferior to adults and consequently are unable to achieve the higher altitudes in the fall.
Turn Turn Turn (The Byrds)
Journal of Physiology (1997), 499.P, 9S
Birds over Mount Everest: extreme hypoxia tolerance
Peter Scheid and Hashim Shams
Institut für Physiologie, Ruhr-Universität Bochum, 44780 Bochum, Germany
Hypoxaemia is a potentially life-threatening situation for mammals. Only few men have succeeded in climbing the summit of Mount Everest, at an altitude of 8848 m, without supplemental oxygen. In contrast, several bird species have been observed to fly at extreme altitudes, the record-holder being a vulture that has collided with an airplane at an altitude of over 11 000 m. The bar-headed goose (Anser indicus) resides in India at sea level and crosses, on its migratory path to the Tibetan highlands, over the Himalayan mountains. How can this extreme hypoxia tolerance of birds be explained?
Birds differ from mammals with respect to the structure of their gas-exchanging organs. Rather than consisting of bronchi and blind-ending alveoli, the lungs of birds consist of long, narrow tubes, the parabronchi, which are open at both ends and are ventilated by the action of a number of wide air sacs. Fine air-filled capillaries leave the parabronchi and intertwine with equally fine blood capillaries for gas exchange. This cross-current system of gas exchange has been shown to have a higher gas exchange efficiency than the alveolar pool system of mammals. The higher efficiency is due to the peculiar arrangement of parabronchial air flow and blood flow in the capillaries, viz. the cross-current flow. Could this be the key for understanding the superiority of birds at high altitude, when oxygen is sparse?
We have performed experiments in the laboratory on the Pekin duck, using a plethysmograph that allowed measurements of respiratory variables in awake, unmolested animals. When lowering the oxygen partial pressure (PO2), the birds increased their ventilation and cardiac output, and arterial PO2 and PCO2 values dropped, qualitatively similar to the situation in man. Without adaptation, the 'lowlander' duck could be brought to an equivalent altitude of over 12 000 m without apparent ill effects.
The most remarkable quantitative result was the extremely low arterial PO2 and PCO2 values at the extreme hypoxic levels. In fact, the inspired arterial differences in these values dropped to below 1 kPa, and the caudal-to-cranial air sac differences approached zero. This meant that ventilation had increased to such a degree that the gas at the gas-blood membrane in the air capillaries had almost the composition of the inspired gas. Under these conditions, the advantage in efficiency of the parabronchial over the alveolar system had disappeared, since the functionally infinite air flow obviously no longer allowed distinction between the cross-current (parabronchial) and pool (alveolar) sytems. Hence the extreme hypoxia tolerance of birds cannot be explained on the basis of differences in the external gas exchange organ.
What else could be the reason for the differences in hypoxia tolerance between mammals and birds? The other members in the gas transport chain are remarkably similar in both vertebrate classes: cardiac output and its increase with hypoxia; oxygen capacity and binding properties of haemoglobin; red cell size, etc. We have very few definite answers to this question yet. It is notable, though, that the flight muscles in particular have a very high capillary and mitochondrial density and a high activity of oxidative enzymes. However, these differences are quantitative at best. One interesting feature is the apparent absence of hypocapnic brain vasoconstriction in birds. This could grant the birds a higher brain blood flow during the respiratory alkalosis at high altitude and might allow the bird a higher ventilation, for the sake of oxygen, with more severe hypocapnia.
---------------------------Another paper from here-----------------------------------------------------------
Migration of Birds
Altitude of Flight Migration
--------------------------------------------------------------------------------
The factors regulating the heights of bird migration are not clear. High-altitude flight may be used to locate familiar landmarks, fly over fog or clouds, surmount physical barriers, gain advantage of a following wind, or maintain a better physiological balance. Meteorological conditions probably account for most of the high-altitude records. Wind conditions at ground level are usually quite different in direction and velocity than at points higher up. In general, human estimates of bird heights are quite unreliable except under special conditions, and these estimates will vary with the eyesight of the observer. Lucanus (1911) found a European sparrow hawk could be distinguished at 800 feet but disappeared from sight at 2,800 feet. A rook (a European member of the crow family) could be recognized at 1,000 feet but disappeared from sight at 3,300 feet. Meinertzhagen (1955) did an interesting experiment with an inflated model of a vulture painted black; it had a wing expanse of 7 feet 10 inches. When released from an airplane at 4,700 feet, it was barely visible and invisible without binoculars at 5,800 feet. At 7,000 feet it was not picked up even when x12 binoculars were used.
At one time students of bird migration believed normal migratory movements took place at heights above 15,000 feet. They reasoned, somewhat uncertainly, that flying became easier as altitude was gained. It has now been shown, through comprehensive radar studies, that 95 percent of the migratory movements occur at less than 10,000 feet, and the bulk of the movements occur under 3,000 feet. However, birds can and do fly well over 15,000 feet without apparent ill effects. The physiology of long-distance flight at high altitudes is of great interest but can only be touched on briefly in this discussion.
Bird flight at 20,000 feet, where less than half the oxygen is present than at sea level, is impressive if only because the work is achieved by living muscle tissue. A Himalayan mountain climber at 16,000 feet was rather amazed when a flock of geese flew north 2 miles over his head honking as they went (Swan 1970). At 20,000 feet a man has a hard time talking and running or other rapid movements are out of the question; but those geese were probably flying at 27,000 feet and even calling while they traveled at this tremendous height.
Accurate observations on the altitude of migratory flights is scanty, although altimeter observations from airplanes and radar are becoming more frequent in the literature. An example is the report of a mallard struck by a commercial airliner at 21,000 feet over the Nevada desert (Manville 1963). It is, of course, obvious that some birds must cross mountain ranges during migration and attain great altitudes. Numerous observations have come from the Himalayas (Geroudet 1954; Swan 1970). Observers at 14,000 feet recorded storks and cranes flying so high that they could be seen only through field glasses. In the same area large vultures were seen soaring at 25,000 feet and an eagle carcass was found at 26,000 feet. The expedition to Mt. Everest in 1952 found skeletons of a pintail and a black-tailed godwit at 16,400 feet on Khumbu Glacier (Geroudet 1954). Bar-headed geese have been observed flying over the highest peaks (29,000+ feet) even though a 10,000-foot pass was nearby. Probably 30 or more species regularly cross these high passes (Swan 1970).
Except to fly over high mountain ranges, birds rarely fly as high as those traveling down the western Atlantic (Richardson 1972). Many of these birds are making long-distance flights to eastern South America and beyond. Therefore, flight at high altitudes in this region is probably advantageous for them. Richardson postulated stronger advantageous tail winds were found higher up and the cooler air minimized evaporative water losses. This investigator found air temperatures averaged 35°F at 10,000 feet over Nova Scotia in September. The lower the ambient temperature, the more heat can be lost by convection and the less water is required for cooling. Also, a bird flying high can achieve the same range as one flying at sea level but must cruise at a higher speed with a corresponding increase in power output and oxygen consumption. But the increased cruising speed results in shorter flight time and less interference from wind (Pennycuick 1969).
Another postulate favoring the high-altitude flying theory was that the wonderful vision of birds was their sole guidance during migratory flights. To keep landmarks in view, birds were obliged to fly high, particularly when crossing wide areas of water. This will be considered in greater detail in the section, "Orientation and Navigation," so here it will be sufficient to say that birds rely only in part upon landmarks to guide them on migration. Also, it must be remembered that definite physical limitations to the range of visibility exist even under perfect atmospheric conditions. Chief of these is the curvature of the earth's surface. Thus, if birds crossing the Gulf of Mexico to Louisiana and Florida flew at a height of 5 miles, they would still be unable to see a third of the way across (during daylight hours). And yet this trip is made twice each year, much of the distance probably at night, by thousands of thrushes, warblers, and others.
The altitude of migration depends upon the species of bird, weather, time of day or year, and geographical features. Nocturnal migrants, studied by radar, appear to fly at different altitudes at different times during the night. Birds generally take off shortly after sundown and rapidly gain maximum altitude. This peak is maintained until around midnight, then the travelers gradually descend until daylight. For most small birds the favored altitude appears to be between 500 and 1,000 feet (Bellrose 1971), but radar studies have found some nocturnal migrants (probably shorebirds) over the ocean were at 15,000 or even 20,000 feet (Lack 1960b; Nisbet 1963b; Richardson 1972). Observations made from lighthouses and other vantage points indicate that certain migrants commonly travel at altitudes of a very few feet to a few hundred feet above sea or land. Sandpipers, northern phalaropes, and various sea ducks have been seen flying so low they were visible only as they topped a wave. Observers stationed at lighthouses and lightships off the English coast have similarly recorded the passage of landbirds flying just above the surface of the water and rarely above 200 feet. During the World Wars, broad areas in the air were under constant surveillance, and many airplane pilots and observers took more than a casual interest in birds. Of the several hundred records resulting from their observations, only 36 were of birds flying above 5,000 feet and only 7 above 8,500 feet. Cranes were once recorded at an altitude of 15,000 feet, while the lapwing was the bird most frequently seen at high levels, 8,500 feet being its greatest recorded altitude. Records of the U.S. Civil Aeronautics Administration show that over two-thirds of all the bird-aircraft collisions occur below 2,000 feet and practically none occur above 6,000 feet (Williams 1950).
Recently, radar has aided greatly in determining differences in the altitude of bird flight. Nocturnal migrants appear to fly slightly higher, on the average, than diurnal migrants, but daytime flights may be influenced more by cloud cover (Lack 1960a; Eastwood and Rider 1965). Bellrose (1971) found little difference in the altitudinal distribution of small nocturnal migrants under clear or overcast skies. Many night migrating birds are killed each year by striking lighthouses, television towers or other man-made illuminated obstructions, but this does not furnish proof that low altitudes are generally used during nocturnal flight because these accidents occur chiefly in foggy weather. Under such conditions, migrating birds seem to be attracted to and confused by lights. Seabirds, such as loons, eiders, and scoters, generally fly very low over the water but gain altitude when land is crossed. The reverse is true for landbirds (Dorst 1963; Bergman and Donner 1964; Eastwood and Rider 1965). There may be a seasonal difference in the altitude of migration, but the evidence is conflicting. Radar echoes studied by Bellrose and Graber in Illinois (1963) showed fall migrants flew higher than spring migrants. They speculated this difference was related to the winds during the fall being more favorable for southerly migration at higher altitudes, while winds at these altitudes in the spring would be less favorable for northerly migration. Eastwood and Rider (1965) studied seasonal migration patterns in England and found the reverse to be true. They suggested one reason for this seasonal difference was that flocks of fall migrants included many young birds whose flight capabilities are inferior to adults and consequently are unable to achieve the higher altitudes in the fall.
Turn Turn Turn (The Byrds)
Adul
Elite Member
As said in Monty Python and the holy Grail -
"Well is it an african Swallow or a European swallow?"
"Well is it an african Swallow or a European swallow?"
dennilfloss
I, for one, appreciate your efforts. I can't immagine it's easy to find information on such obscure subjects. My work includes staying a little bit informed on how humans respond physiologically to high altitude situations. Without reading these articles, I would have bet that birds would have the same limitations as us humans.
Nick
I, for one, appreciate your efforts. I can't immagine it's easy to find information on such obscure subjects. My work includes staying a little bit informed on how humans respond physiologically to high altitude situations. Without reading these articles, I would have bet that birds would have the same limitations as us humans.
Nick
Dennil, at the risk of being a science nerd like Ross on Friends, I have to admit, that was some very interesting reading. Now I know more about birds at altitude and their migratory behavior than I would have ever imagined
An interesting topic & a personal observation... I duck hunted for many years & only observed this one year. It was a year of low temps nation wide & there were more ducks than usual migrating at high altitudes.
Most years duck flocks travel where they are medium sized specks. This compares to about 1 & 1/2 miles. You can see wing motion but no body details.
This one year, 1983, the flocks were up,out of sight, even with binoculars. We would usually hear them braking from the air across their wings as they came down to the lakes. There were several reports on the local news that year of pilots seeing flocks of ducks between 15,000 & 20,000 ft.
Tis a beautiful sight to have a clear blue sky, no clouds & see these tiny specks appear & gradually turn into ducks that land in the water a few yards away. It was not only mallards, but gadwalls & pintails as well.
Most years duck flocks travel where they are medium sized specks. This compares to about 1 & 1/2 miles. You can see wing motion but no body details.
This one year, 1983, the flocks were up,out of sight, even with binoculars. We would usually hear them braking from the air across their wings as they came down to the lakes. There were several reports on the local news that year of pilots seeing flocks of ducks between 15,000 & 20,000 ft.
Tis a beautiful sight to have a clear blue sky, no clouds & see these tiny specks appear & gradually turn into ducks that land in the water a few yards away. It was not only mallards, but gadwalls & pintails as well.
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