The most common and most likely answer to this crossword clue is the 6 plus 8 letter word EGRETS (GREETS)
E
G
R
E
T
S
(
G
R
E
E
T
S
)
Buddy explains!
The straight part
We know that "birds" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case birds = egrets (greets).The cryptic/wordplay part
In cryptic crossword there's often an wordplay/cryptic part as well.This part involves a more complex hint, such as an anagram, homophone, hidden word, etc.
Sadly, We don't have an explanation for this specific crossword clue yet.