[seismic wonder2]

Why do my pigeons sometimes grunt when I pick them up?

I assume it is to express some sort of displeasure because sometimes it comes with a wing-slap or two.
They sometimes hunker down and start grunting, really quiet like, I can barely hear it. Then stand up tall and coo at me.
Strange.....

 

[spirit wings]

you already answered your own question, can't think of any other reason why they grunt, and they are not talking.

 

[coyotejoe]

I've noticed that when my King cocks are strutting their stuff they do a lot of very loud grunting like an alligator. I've never heard that from the Homers, Rollers of Ferals.