As for the "death toll" the death rate (as listed) is very low for a zoo the size of San Diego. Don't forget they have (I am fairly certain) the largest animal collection in the country. Most animals have short lifespans compared to humans. It should be a matter of course that animals die regularly in zoos - this is an unavoidable fact of nature and nothing to decry (unless it can be proven that it is due to staff negligence, which it will not be at a zoo of this caliber).