Crossword Genius

Some birds do this at the speed of a fighter plane? (7)

Ross

I believe the answer is:

migrate

I believe this clue is a double definition.

'some birds do this' is the first definition.

'the speed of a fighter plane?' is the second definition.
(the rate of a MiG Russian fighter)

'at' is the link.

(Other definitions for migrate that I've seen before include "move base?" , "Move from one country to another to settle" , "Ragtime (anag)" , "Move with the seasons" , "Change habitat (seasonally, perhaps)" .)

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