As of right now, we do not know who Gary's lifemate is. However, we can make some educated guesses based on the information that we do have.
Gary is a Male American Kestrel Falco sparverius. He was born in the wild and released into captivity at the Peregrine Fund in Boise, Idaho on May 5th, 2009. He was banded (legally required for all captive-bred Peregrine Falcons) with US Fish & Wildlife Service Band Number 6034041.
Since he was born in the wild and not raised in captivity, it is likely that Gary has never met his potential lifemate. In fact, it is possible that his lifemate could be living anywhere in North or South America since American Kestrels are found throughout both continents.
If Gary were to meet his potential lifemate, there would be no guarantee that they would hit it off immediately. Birds of prey are notoriously picky when it comes to choosing a mate and will often go through several partners before finding one that they are compatible with. Additionally, even if two birds are compatible, they may still not stay together for life as pairs will sometimes divorce later down the road.