This cartoon was shown about the late 70's , early 80's. Not a known character. It was about a mamma bird and her babies. One that needed more attention than the others. She was teaching them how to fly. All did well except for that special one. I remember the mom telling him he had to fly and he would reply with no, no, no. I think they were vultures.

It might be something from the Warner Bros studio's (Bugs Bunny) They had a vulture that was like a "Mortiner Snerd" character. He was shy and kept on saying "OH No no no."

Definitely sounds like the vulture's from Bugs Bunny. Of all the Bugs' shows, I always found that one most entertaining. Perhaps because eventually when Mortimer does fly, he's singing a song to the tune of "Bringing home a baby bumblebee".
Ok, so I'm a bit "off"

The character was Beaky Buzzard (http://en.wikipedia.org/wiki/Beaky_Buzzard). His voice was indeed modeled after Mortimer Snerd's. :)