Sad News from the Calgary Zoo

[Brent F]

I still have a hard time with the idea of pollution from hands being the cause because I wouldn't think they would all die so closely together. It doesn’t make sense to me that 400 hands per hour for months does nothing, then suddenly they all die in one day? I wouldn't think pollution would act that quickly.

A more plausible scenario that could be caused by hands would be introduction of a disease such as salmonella which is a common problem for zoos. I used salmonella as an example because when I worked at a zoo in the late 70s salmonella was a common reason for animals dying suddenly.

Another plausible scenario would be accidental addition / spillage of a large enough quantity of a chemical used at a zoo. For example, there are sterilizing chemicals in displays to prevent disease from the feces. A tub of chemical accidentally introduced could cause sudden death. There could be a copper based chemical, which as Albert mentioned, would be very toxic. Copper is common in landscaping material as a rot inhibitor.