As a wildlife photographer one thing I've learnt is you have to be prepared for failure and frustration. I'd guess 90%of the times I go out taking wildlife photos I go home without getting photos that are better than the ones I already have in my portfolio. It's very rare you get the perfect light, nice background and willing model, most times you think things are stacked against you.
This is one recent example when things didn't go my way that ended in frustration. On a walk around a local nature reserve I could hear the small birds alarm calling which usually means there's a predator about. Sure enough I spotted this Tawny Owl in a tree only 20m from me I had to be quick and managed to fire off a couple of shots before the Owl took flight. I thought I'd managed to get the photos but when I looked on the back of the camera found that at the critical moment the blustery wind had blown a branch in front of the owls face, these photos would be going in the bin.