For people that are new to the zookeeping field, I have a few pieces of advice that I'd like to give you. The first one that I want to talk about today is being humble.
About six months into my keeper internship in the children's zoo at the San Francisco Zoo I already thought I knew it all. I took liberties with animals that now I know I should never have. One day without asking anyone I decided to walk one of the horses that lived there through the petting zoo area to get her some exercise and also to show herself (and myself) off to zoo guests. I knew that she could be a nervous animal at times, but I was also very confident in my abilities to control the situation. It was a relatively slow day and nothing went wrong. I walked her from once side of the corral to the other, stopping a few times to let her meet guests, and then returned her to her exhibit area. As soon as I had put her back I was immediately approached by my supervisor for a meeting in his office where he proceeded to tear me a new orifice about walking her through a public area. He said things like "you aren't experienced enough yet", "you need to ask permission", and "someone could have gotten hurt". I brushed it off and didn't pay too much attention to him because I knew that I was good at this job.
Another time, I took our black rat snake out of his smallish exhibit which had no natural light and let him slither around in a patch of grass in a behind the scenes area inaccessible to the public. I thought I was doing a really nice thing for the animal, but once again, after I brought him back to his home I got in trouble with the boss. This time, I got written up for it. Still, I didn't really pay too much attention to it because I knew I was already a good keeper with good animal sense.
Part of the daily routine of the "Yellow Barn" string at the children's zoo was walking our steer Oscar from his off-exhibit corral to the public exhibit area in the morning and then back again around closing time. One day I decided I was ready to halter up Oscar and walk him back to his night yard by myself, again, without asking someone. I was chatting with a guest, haltering him up at the same time, and paying more attention to the guest than I was the animal. I had done this dozens of times with supervision and I had gotten complacent, which now I know is never a good thing, even with animals you know really well.