The most common and most likely answer to this crossword clue is the 9 letter word SCREECHES
I've seen this crossword clue in The Times
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Buddy explains!

The straight part
We know that "bird's cries?" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case bird's cries? = screeches.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.
What does SCREECHES mean?
SCREECHES noun- A high-pitched strident or piercing sound, such as that between a moving object and any surface.
- A harsh, shrill cry, as of one in acute pain or in fright; a shriek; a scream.
- (Newfoundlander) Newfoundland rum.
- A form of home-made rye whiskey made from used oak rye barrels from a distillery.
- To make such a sound.
- To travel very fast, as if making the sounds of brakes being released