>

Can’t recall if it was the Dodo or the Great Auk, but a wealthy person realized that a formerly-common bird was becoming rare, and he didn’t have an egg in his collection. He hired a ship that was going near their habitat anyway to bring him an egg. Sailors found a pair, killed them, and collected the egg for their sponsor. That was the last reported sighting of the species.
"a cutting tool was used to intentionally make an opening in the fence of the small cat’s habitat, and a similar cut was found at a habitat for small monkeys" >

Definitely some crazy PETA people >

Or people looking to grab them to sell illicitly as pets.  There is a pretty active black market for exotic animals.
PETA would have gone after something bigger to make a big show of it. >

Years ago the local zoo lost a pigmy falcon that was due to lay eggs at any time. Someone just cut their way into the enclosure and made off with it and it was never recovered. >

That's extra heartbreaking given how many people out there aren't just hoarding exotic animals, but collecting eggs and other specimens that do not involve keeping the animals alive.