Bats pass endless migrant birds (10)

I believe the answer is:

ptarmigans

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

'bats pass endless migrant' is the wordplay.
'bats' is an anagram indicator (I've seen this in other clues).
'endless' means to remove the last letter.
'pass' with its final letter taken away is 'pas'.
'pas'+'migrant'='pasmigrant'
'pasmigrant' with letters rearranged gives 'PTARMIGANS'.

I've seen this clue in The Times.

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