Success rate?

[hhw]

Considering the difficulty of some of the lesser kept species out there, how many of you more experienced keepers have suffered losses due to husbandry errors? Especially considering the lack of literature for many species, and the likelihood that some of you worked with them back when there was even less knowledge available, I would presume there have been some casualties here and there, despite best efforts.

Basically, with wild caughts of some of the more difficult species, how often would an experienced keeper lose animals? How about for someone who's as throroughly researched and prepared as possible, but lacking practical experience? I realize that it's not too fun to discuss one's mistakes, but I'd really appreciate some candid and honest answers.

I'm not looking to work with any difficult species anytime soon myself, but it's definitely something I will work towards a decade or so from now.