Sorry HSC......If you look at the definition of 'defy' you will see that birds DO defy gravity:
de·fy
dəˈfī/
verb
openly resist or refuse to obey.
"a woman who defies convention"
synonyms:disobey, go against, flout, fly in the face of, disregard, ignore;
I think that birds only TRY to defy gravity.
They do not really succeed or else they would fly into space and leave the earth's gravitational field.
Although,
I suppose they do TRY to resist gravity..... Maybe you do too when you walk or jump ://
Jesus... l've created a monster. We must burn this thread before... the guests come.
It is more accurate to describe them as "overcoming" gravity, temporarily, through the sheer effort of flapping the muscles of their wings, which takes a lot of energy to do so.