High altitude fliers

Subject: High altitude fliers
From: Stephen Ambrose <>
Date: Sat, 04 Apr 1998 17:18:32 +1000
At 08:19 AM 4/3/98 +1000, Pat Macwhirter wrote:
>Dare I ask which bird flies the highest and in what state are their

It appears that the physiological and morphological adaptations of birds
for flying at high altitudes have been largely unstudied. This is probably
due to the difficulty of conducting such studies.

My faithful Prosser (1974) states that high fliers have:

1.  Higher haemoglobin levels (molecules that bind with oxygen to carry it
from the lungs to other body tissues);
2.  A greater concentration of red blood cells in the blood (they carry the
haemoglobin molecules);
3.  Higher myoglobin levels in the muscles. Myoglobin binds to the oxygen
molecules that are delivered to muscle tissue.
4.  A more powerful heart to pump oxygenated blood around the body.

Duncker & Guentert-Durbach (1985) maintain that high fliers also have:

1.  Greater air sac and lung volume, thus allowing larger tidal volumes;
2.  A greater network of blood capillaries taking up oxygen from the lungs;
3.  Thinner lung tissue, thus reducing the distance that oxygen molecules
need to diffuse into the blood capillaries.

Do high fliers also shunt blood to essential organs such as the brain and
heart, have depressed metabolic rates, and greater toleration to build up
in lactic acid, as in diving birds? 

How do they thermoregulate effectively at altitudes where ambient
temperatures are extremely low?  There would also be a risk of excessive
loss of body water at such high altitudes and flight activity, so how do
these birds avoid excessive dehydration?

Can anyone else answer these questions?


Prosser, C.L. (1974). Comparative Animal Physiology (W.B. Saunders Co.,

Duncker, H.-R. & Guentert-Durbach, M. (1985). Morphometric analysis of tthe
avian respiratory system. In: Duncker, H.-R. & Fleischer, G. (eds).
Functional Morphology in Vertebrates (Gustav Fischer Verlag, Stuttgart).
Pp. 383-7.

Dr Stephen Ambrose
Research Manager
Birds Australia (Royal Australasian Ornithologists Union)
Australian Bird Research Centre
415 Riversdale Road,
Hawthorn East,
VIC   3123.
Tel:    +61 3 9882 2622
Fax:    +61 3 9882 2677
Email:  S.Ambrose <>  (at work)
             <>   (at home)

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