To be entirely honest, I'd say most of them are. Chickens—I can't speak for other birds—don't seem to think about the future much. After a mink attack a few years ago that was an absolute bloodbath, I found one of the survivors unconcernedly picking at the bloody skull of one of the less fortunate. She waddled on in a peeved manner after I shooed her away in horror and started picking up the corpses.I'm wondering how much of the concerns are reflections of our own feelings, as opposed to those of the birds.
Many of their reactions to events are dictated by how they perceive the event rather than what the event actually is. Animals in general have a kind of spotty perception of events that isn't always easy for a human to understand or see the pattern to. I certainly won't pretend that I can. Still, I'd be willing to bet that the day that I caught all my birds to treat them for scaly leg mites terrified them far more than butchering day. (The bruises I received on my hands and arms back my theory up.)
What causes a bird to react to a stimuli as threatening is quite interesting and not at all easy to put into words. I don't know enough or have enough certainty on what I have observed to be able to give any explanations without almost certainly being wrong on some or most of it.