YOU SAID:

I saw a bird flying there

INTO JAPANESE

そこに飛んでいる鳥を見た

BACK INTO ENGLISH

I saw a flying bird there.

INTO JAPANESE

私はそこに飛んでいる鳥を見た。

BACK INTO ENGLISH

I saw a bird flying there.

INTO JAPANESE

私は鳥がそこに飛んでいるのを見た。

BACK INTO ENGLISH

I saw a bird flying there.