Track bird (4)

I believe the answer is:

rail

This clue is a double definition.

'track' is the first definition.
('rail' can be a synonym of 'track')

'bird' is the second definition.
(rail is a kind of bird)

(Other definitions for rail that I've seen before include "Line" , "Bar - marsh bird" , "Water bird; barrier" , "Bar or banister" , "Kind of transport" .)

I've seen this clue in The Telegraph.

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