Why do Pokemon like Staraptor have a second type?

They can easily be only Flying-type.

Pleaselog inorregisterto add a comment.

Game Freak Logic and RoostWell, first of all Birds are Common and Normal, and Game Freak just wanted it that way as already mentioned. They may also want it to be Balanced Gameplay,howeverRoostis another Main Factor

Before Gen VI any Pure Flying type(Tornadus) would turn into a ??? typeThat would be A Problem. Game Freak thought of it and Fixed it in Gen VI, so now if they decide to make any other Pokemon like that they’ll have no Problem. In Gen VI if Tornadus uses Roost, he will become a Normal type for the Rest of the Turn

There are some explainations to this one though. A normal type is generally regarded as a Pokemon that is not too much out of the ordinary (with exceptions of course).Most Pokemon that get a normal typing are those that are part of the general and simpler Pokemon.Staraptor and many other Normal/Flying types are so most probably becausethey are not very much out of the ordinary, and use very simple tactics and moves.This is also the reason Tornadus is not a Normal type, being the only pure Flying type.

Hope I helped!