What is the professional title of a messenger-bird-keeper?

Solution 1:

I think fancier and keeper would apply generally to those who keep and breed pigeons, but the OP requires a term for someone charged with the care and organisation of, specifically, carrier/messenger pigeons.

I've come across this reference:

The Pigeoneers ™

2012 - USA - English - 111 minutes - Alessandro Croseri Productions LLC Directed by: Alessandro Croseri Featuring: Col. Clifford A. Poutre, Chief Pigeoneer US Army Signal Corps, 1936-1943

In this debut feature film, director Alessandro Croseri delivers a stunningly beautiful ode to combat pigeons and their pigeoneers. The documentary follows Col. Clifford Poutre at age 103 during the final year of his life and examines his innovations in the training of homing pigeons for combat missions during World War II...