Passenger Pigeon - are they really a extinct species?

Passenger pigeons once numbered billions are now regarded as extinct. They were killed because of damage inflicted on crops, but once people started to kill them to eat them, they disappeared in just a hundred years. Martha, thought to be the world's last Passenger Pigeon, died on September 1, 1914, at the Cincinnati Zoo.Until recently I was of the opinion that passenger pigeons are extinct, but I'm not quite sure about that.A few days ago I told a friend about them and showed him pictures. And surprisingly to me he told me that his grandfather kept such pigeons for over 40 years. Now I believe that maybe somewhere in the world there are separate populations and species is not entirely disappeared.