... is the reduction of air density at high elevation and the reduction in the effectiveness of lift production that accompanies it. As a species, turkey vultures ( Cathartes aura ) inhabit a >3000 m elevation range, and fly considerably higher, necessitating that they accommodate for a 27% change in air density...

...H. Schmaljohann; F. Liechti SUMMARY Birds adjust their flight behaviour to the physical properties of the air. Lift and drag, the two major properties in aerodynamics, are highly dependent on air density. With decreasing air density drag is reduced and lift per wingbeat decreases. According...

... interaction air density air pressure oxygen Altitudinal gradients are characterized by rapid changes in the physical environment. Mean air temperature drops by 6°C km -1 , such that the temperature change in climbing from sea level to 4000 m is roughly equivalent to the change experienced...

...Douglas L. Altshuler; Robert Dudley SUMMARY Hovering flight is one of the most energetically demanding forms of animal locomotion. Despite the cost, hummingbirds regularly hover at high elevations,where flight is doubly challenging because of reduced air density and oxygen availability. We...

... and reduced wing area was compared with that before their moult. Hummingbirds were flown in reduced air densities using normoxic heliox so that a range of flight energetics was displayed. The rate of moulting and the extent of wing area loss varied among individuals. One female could tolerate a 30 % loss...

... of the respiratory system were probably not limiting to a significant extent. Compared with hummingbirds in our previous studies, the present experimental birds were heavier, had resultant shorter hover-feeding durations and experienced aerodynamic failure at higher air densities. Because hummingbirds have...

... metabolism via variable oxygen partial pressure and/or altered flight mechanics via variable air densities. Limits to the locomotor capacity of hovering ruby-throated hummingbirds ( Archilochus colubris ) were unequivocally indicated by aerodynamic failure in either air/helium or air/heliox mixtures. Air...