Which poem used to display big birds? (4)

I believe the answer is:

emus

'big birds?' is the definition.
(emus are large birds)

'which poem used to display' is the wordplay.
'to display' indicates the answer is hidden within the clue (I've seen 'displaying' mean this).
'EMUS' can be found hidden inside 'which poem used'.

(Other definitions for emus that I've seen before include "Fast, but not high-fliers" , "Large flightless birds of Australia" , "laboratory units" , "Largest native Australian birds" , "Running birds" .)

I've seen this clue in the Sydney Morning Herald.

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