9 research outputs found
Energy Expenditure and Metabolic Changes of Free-Flying Migrating Northern Bald Ibis
Many migrating birds undertake extraordinary long flights. How birds are able to perform such endurance flights of over 100-hour durations is still poorly understood. We examined energy expenditure and physiological changes in Northern Bald Ibis Geronticus eremite during natural flights using birds trained to follow an ultra-light aircraft. Because these birds were tame, with foster parents, we were able to bleed them immediately prior to and after each flight. Flight duration was experimentally designed ranging between one and almost four hours continuous flights. Energy expenditure during flight was estimated using doubly-labelled-water while physiological properties were assessed through blood chemistry including plasma metabolites, enzymes, electrolytes, blood gases, and reactive oxygen compounds. Instantaneous energy expenditure decreased with flight duration, and the birds appeared to balance aerobic and anaerobic metabolism, using fat, carbohydrate and protein as fuel. This made flight both economic and tolerable. The observed effects resemble classical exercise adaptations that can limit duration of exercise while reducing energetic output. There were also in-flight benefits that enable power output variation from cruising to manoeuvring. These adaptations share characteristics with physiological processes that have facilitated other athletic feats in nature and might enable the extraordinary long flights of migratory birds as well
Post-flight versus pre-flight changes in plasma reactive oxygen metabolites in relation to flight duration.
<p>For further explanation see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0134433#pone.0134433.g002" target="_blank">Fig 2</a>.</p
Post-flight versus pre-flight changes in plasma levels of fat and carbohydrate metabolites in relation to flight duration (flight-time in minutes).
<p>Best-fit regression lines are shown for significant relationships with flight duration. Horizontal dotted lines show the respective zero (no change) line.</p
Post-flight versus pre-flight changes in plasma levels of HCT, pH and blood gases in relation to flight duration.
<p>For further explanation see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0134433#pone.0134433.g002" target="_blank">Fig 2</a>.</p
Energy expenditure during flight.
<p><b>A</b>: Mean (± s.d.) energy expenditure (kJ h<sup>-1</sup>) during rest and during flight. <b>B</b>: Relationship between flight energy expenditure EE (kJ h<sup>-1</sup>) and flight duration.</p
Post-flight versus pre-flight changes in plasma electrolytes in relation to flight duration.
<p>For further explanation see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0134433#pone.0134433.g002" target="_blank">Fig 2</a>.</p
Post-flight versus pre-flight changes in plasma levels of LDH, CK and protein metabolites in relation to flight duration.
<p>For further explanation see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0134433#pone.0134433.g002" target="_blank">Fig 2</a>.</p