From Field and Study

Abstract

The Energetics of Migrating Hummingbirds.-Theenergy problems of migrating hummingbirds have been of recurrent interest to students of avian biology.While the consensus among ornithologists seems to be that Ruby-throated Hummingbirds (Arck&chus coZ~&ris) do make the migratory flight across the Gulf of Mexico, a distance of over 500 miles, physiologists have not been able to demonstrate their energetic capability to do so.Pearson (Condor, 52, 1950:145-152) measured the metabolism of Anna and Allen hummingbirds (Colypte anna and Selusphorus satin).The metaholism of hovering S. so&n averaged 85 cc.&/gm.ihr., while that of C. anna averaged 68 cc.Oe/gm./hr.By assuming that migrating hummingbirds have a flight speed of 50 miles per hour, a metabolic rate of 80cc.&/gm./hr., and that they carry one gram of fat as fuel, he estimated the flight range of A. colubris to be 385 miles (1 gm.fat = 9 Cal., 1 liter of oxygen consumed=4.69Cal.).