Likewise, we hit a bird on a pitch dark night over Germany, descending through 14000 feet. Yet sometimes you fly through a whole swarm of birds in broad daylight on short final without hitting one. Sometimes you know you've hit a bird, you've seen it, you've heard it, but can find no evidence whatsoever of any impact or damage after landing, leading to some awkward looks from the engineers you've called out to attend to the aircraft ('And you say you saw the bird exactly where, captain?' 'Oh you heard it as well...right...').