Fun with the birds? (5)

I believe the answer is:

larks

I'm a little stuck... Click here to teach me more about this clue!

'the birds?' is the definition.
(lark is a kind of bird)

I cannot understand how the rest of the clue works.

(Other definitions for larks that I've seen before include "High jinks" , "[EARLY BIRD]?" , "Cavorting" , "early risers?" , "guys" .)

I've seen this clue in The Globe and Mail.

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