My opinion, the core engine is the one that will cause the compressor stall. That's the section that drives the fan. From personal experience and many stories from other folks, you can have an unbelievable amount of damage to a N1 fan and never know it from the performance or engine indications. I'm not saying that a N1 fan won't cause a stall, but the core engine is more likely to be the culprit.
All true
mostly the talk about the core compressor is the highest speed compressor which does not drive the fan. However its the effect on the core compressor that causes the surge and the effect that goes with birds is the flow capacity loss out of the fan due to damage unbalancing the airflows into the core compressor.
Yes indeed there are lots of horrible looking fan damages that never bother the core compressor (good news). And most of the bird stuff gets centrifuged out the fan duct or doesn't cause mechanical damage in the core (good news).
... but for those few events that do result in a surge coupled with damage (not just the temporary blockage of the air by the bird itself) is how I thought the question was posed
as always in the tech section we tend to provide random bits of info and hope that the question gets answered and we all learn something
