The most common and most likely answer to this crossword clue is the 5 letter word HAWKS
I've seen this crossword clue in Financial Times
H
A
W
K
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 = hawks.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 HAWKS mean?
HAWKS noun- A diurnal predatory bird of the family Accipitridae, smaller than an eagle.
- Any diurnal predatory terrestrial bird of similar size and appearance to the accipitrid hawks, such as a falcon
- An advocate of aggressive political positions and actions.
- An uncooperative or purely-selfish participant in an exchange or game, especially when untrusting, acquisitive or treacherous. Refers specifically to the Prisoner's Dilemma, alias the Hawk-Dove game.
- To hunt with a hawk.
- To make an attack while on the wing; to soar and strike like a hawk.
- A plasterer's tool, made of a flat surface with a handle below, used to hold an amount of plaster prior to application to the wall or ceiling being worked on: a mortarboard.
- To sell; to offer for sale by outcry in the street; to carry (merchandise) about from place to place for sale; to peddle.
- A noisy effort to force up phlegm from the throat.
- To cough up something from one's throat.
- To try to cough up something from one's throat; to clear the throat loudly.