[eru]

Didn't they have wireless communication? What benefits did the pigeons have?

[EvanAnderson]

Triangulation of the sender (or the receiver by way of emissions of the receiving set) was a problem in WWII. There's also the problem of traffic analysis. I would think birds would be immune to both.

[jonplackett]

Harder to intercept?

[eru]

You'd want to encrypt your communication in either case.