Pig Spawns ' Random, Timed?

Does anyone know how the Pigs are setup in each match? Lately I´ve been spending the first minute scouting a map looking for pigs and usually do not find any, or maybe one. Then I´ll be in an area explored a few minutes ago as the Fireteam does an objective and there will be groups of them.
I am not sure if they spawn on a timer, on how much the Fireteam progresses, or maybe if I have done X damage to the Fireteam. Does anyone have any insight?

Still perfecting Pig Theory, but I believe there’s actually more to this and pigs are spawned per player in specific locations. Which is why you see a bunch of pigs behind the fireteam in addition to an inital pig spawn on the pred side. This seems intentional and allows the FT to cover pigs and have an idea where the pred is going to heal if they want to pursue. Otherwise pigs would just be random uncontested spawns.

It’s definitely not tied to progression, unless downing FTs can despawn pigs which I haven’t tested yet, but doubtful. In general if you lockdown the FT at a camp and they’ve been there awhile you’ll just see 6 pigs standing around the fence because all players have been idled there so long.

Tl;DR Always pigs behind the fireteam or the last active compound spawn

also this as its boar related