Suck, Squeeze, Bang, Blow. Intact bird at intake, Molecular bird at exhaust. Of course, this applies to small birds. A large bird such as a vulture or eagle might bend a fan blade or two. Any engine that ingests a flock of hundreds on takeoff, though, is in grave danger. That would be the same as total engine failure. The larger the engine, of course, the more birds it is able to process.
The day you stop learning is the day you should die.