Zoos can have problems (see also this and this), as one would expect, when people try to cage nonhuman animals (animals) and take away their basic needs and freedom. However, there also can be problems when the animals themselves kill other animals and some, not surprisingly, escape.
I just learned of some very sad and apparently avoidable incidents at the UK's Bristol Zoo that happened in December. The article I read called "Rare warty pigs are lost when male eats his entire family at Bristol zoo" begins:
"A zoo lost some of its most endangered animals when a male warty pig ate his entire family and a rare monkey was eaten for lunch by hungry otters. The incidents happened at Bristol Zoo in December and were shortly followed by further tragedy when three rainbow lorikeets escaped."
An anonymous whistleblower claimed "the deaths and escapes were avoidable."
There are so few warty pigs in the wild that no one knows how many, or how few, there are. These pigs are native to the Visayan Islands in the central Philippines.
In response to these events, a spokesperson for the zoo told reporters, "We actively encourage natural animal behaviors and group dynamics. Our animals are also housed in natural enclosures, replicating environments they would be used to in the wild."
While this and other zoos make attempts to provide "natural" or "semi-natural" environments for their residents, it is impossible to replicate them in captive situations. And, it's well known that the behavior of animals can change when they are confined and housed near others who usually are not their nearest neighbors in the wild. They are incredibly sensitive to visual, auditory, and olfactory stimuli and it's extremely difficult, if not impossible, to know how "extraneous" factors outside of their cages influence their behavior.
While incidents like this are rare, it is essential that they be reported and remedied as long as animals are forced to live in captivity. Although the Bristol Zoo is considered to be a "good zoo," clearly it is not good enough to avoid these tragic events. I share the distress of zoo workers, and perhaps these tragic events will serve notice that zoos can and do change the behavior of their residents and there never can be too much surveillance of their activities.
While the loss of the highly endangered pigs is especially devastating for these fascinating animals, the loss of any animals while living under human care is tragic and events like this must generate serious discussion of how to make "good zoos" better. All zoo residents deserve the best care we can provide them, and perhaps endangered animals like the pigs should be kept elsewhere where they can be more closely monitored, 24/7, if necessary.