Page 219 - Das Wunder der Migration bei Tieren

Hum ming birds be at the ir wings 20 to 80
ti mes per se cond. That they do this wit -
ho ut harm is an in di ca ti on of the ir bo di -
es' per fect structure.
Even tho ugh hum ming birds flap the ir
wings mil li ons of ti mes du ring mig ra ti -
on, the ir musc les do not sus tain the
sligh test damage.

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