Why was a flight delayed because of a bird in the cockpit? This Washington Post article is about a Delta Airlines flight that took off after an initial delay, before turning back again shortly after, because of a bird that managed to stowaway in the cockpit.

My questions,


Would it be dangerous having the bird in the cockpit?
Was the decision to turn back expected or over the top?
Do Delta regulations (or relevant regulations) actually cover something this specific, or would it have been under some catch-all? If so, what would that be?
Have there been any similar incidents?
Does this ever happen on small private aircraft?  (It's not unheard of to find a small bird sitting in your car for some reason - maybe it's the same?) Has it ever happened to anyone here, what's the outcome?


and mostly,


Why didn't they just kill it?


(Aircraft kill small birds by the thousands, I mean - chicken was probably served on board.)
Having a small bird in a cockpit, or anywhere on board, would not be a problem during a normal flight because a normal flight should have a wide safety margin.

However, a situation can change extremely rapidly from safe-and-normal to heavy workload to full-emergency due to any number of factors, including weather, mechanical issues, airspace/congestion, etc.   In a high stress situation, a small bird could be the proverbial tipping point.  So I see and understand the decision to turn back.

It is remotely possible that a small bird could get somewhere it shouldn't, like behind a panel or near electrical lines and cause a short or other serious problem.  Its not terribly likely, but with 100+ lives at stake, why would you risk it?

As for why they didn't just kill it:  Killing it involves catching it, and catching a small bird while still flying a plane is not easy!!