Rook Corvus frugilegus, Corbeau freux.

8 occurrences (4 rook, 2 rooks, 1 rook'd, 1 rooky)

In the opening of scene 3 Act I of The Merry Wives of Windsor the Host of the Garter Inn calls Falstaff "bully rook" and he repeats this half-affectionate half-disparaging nickname three times in Act II scene 1.

The remaining occurrences of "rook" are either in the plural or their context features other birds of the crow family (corvidae), evoking the highly gregarious behaviour of the rooks.

Shakespeare literally crams birds into these verses. Either by giving a list of different species:

When turtles tread, and rooks, and daws,

(LLL 5 2 897)

or a list of birds of the same family.

By maggot-pies, and choughs, and rooks, brought forth

(MAC 3 4 124)

When it is not in a list context, and when the subject is already a raven or a crow, he chooses to make "rook" into a verb:

The raven rook'd her on the chimney's top,

(3H6 5 6 47)

or an adjective:

Makes wing to th'rooky wood;

(MAC 3 2 51)

Shakespeare succeeded then in describing and evoking the multitude of a rookery before the word was invented.