Is this real? Can it deliver to a balcony? Or does it just drop it off at your doorstep?
Since sending messages by homing pigeon requires taking a pigeon from location A and then releasing it with a message so it will fly back home to location A, I'm going to guess this isn't real. Unless every customer has to install a pigeon coop to raise birds that will head home to that location.
They have servos on the wings and neck of the birds. On the back is an rPi or some small computer. They have a long wire antenna (looked to be 1 meter long) dangling from the computer.
I am guessing they are controlling the servos via the rPi and doing midcourse updates over the air.