The Bible says eagles, All the manuscripts say Eagles,but still the NIV  will use vulture?
Luke 17 :36-37   New King James
  Two men will be in the field ,the one will be taken and the other left
And they answered and said to Him, Where Lord? So He said to them, Wherever the body is,there the
eagles will be gathered together.
  The Christians are the eagles,and the body would be the Jesus. A example of Eagles gathered together are
Rev Ch 4 and Ch 5  
So the Lord was explaining where the christians were going to go in the rapture. It had nothing to do with eagles eating dead meat, Nor does that make any sense in the context of passage.  Vulture is not used anywhere in Greek Manuscripts. So Jesus never said vulture ,never meant vulture, He said
EAGLES !!!
Also read 
Rev 8:13 where angel is actually translated eagle in the M and also the NU  for more info on the M and NU read Here.
IS 40:31 They shall mount up with wings like Eagles .
EAGLES