They don't have to be smart to fool the birds (10)

I believe the answer is:

scarecrows

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

'they don't have to be smart' is the definition.
The definition suggests an adverb but the answer is not.

'fool the birds' is the wordplay.
'fool' becomes 'scare' (I am not sure about this - if you are sure you should believe this answer much more).
'the birds' becomes 'crows' (crow is a kind of bird).
'scare'+'crows'='SCARECROWS'

'to' is the link.

Can you help me to learn more?

(Another definition for scarecrows that I've seen is " could cause flyers to abort".)

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

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