No it would still be a bird obviously but it would be empowered by the element of Bug. I suppose we could just give it a bunch of bug type moves instead.
Just remember type does not have to do with species. Piplup is a Bird but it is not a Flying type. Egg Groups have more to do with what the Pokemon physically is:
http://bulbapedia.bulbagarden.net/wiki/Egg_group
As you can see Gligar is a Bug Egg Group despite being a Ground/ Flying type. Gligar is based of a Bug but isn't a Bug type, showing that types don't reflect species.
This is just for future reference. The Hummingbird can stay Grass. But keep this in mind.
Just remember type does not have to do with species. Piplup is a Bird but it is not a Flying type. Egg Groups have more to do with what the Pokemon physically is:
http://bulbapedia.bulbagarden.net/wiki/Egg_group
As you can see Gligar is a Bug Egg Group despite being a Ground/ Flying type. Gligar is based of a Bug but isn't a Bug type, showing that types don't reflect species.
This is just for future reference. The Hummingbird can stay Grass. But keep this in mind.