P8's leaving the barn with at least 13 in the air. Might be more as some of them are changing callsigns after departure and dropping in and out of ADS-B.
These large numbers of P8's have been noted by other planefags recently and I have dug something up that might explain why.
P8's are not only sub hunters but also electronic surveillance equipped.
P8's can hack electronic voice transmissions and forward the data real time via satellite to intel on the ground.
This from an article about the aircraft:
"Such a capability will allow the P-8 to eavesdrop on potential foes communications in a way in which linguists can translate those intercepts in real-time or in near real-time. Using satellite communications, there is a possibility that those linguists may not be on the jet at all, and could even be halfway around the globe."
https:// foxtrotalpha.jalopnik.com/the-navys-p-8-poseidon-spotted-packing-mysterious-new-p-1718488424
This capability is possibly attributed to a new belly mounted antenna array system. Attached image is relevant.
P8's also have long distance video / IR capability and imaging radar that can discern shape of targets on land or sea.
Planefags have been looking for the eyes and ears in the air they may just have been hiding in plain sight all this time.