Plants vs Animals, Round II

The guanaco (a South American wild relative of the llama) looked sick.  There was no denying that.  When the hoofstock keepers asked me to come by and take a look at their male guanaco, I didn’t think that there would be much I could offer in the way of advice or helpful suggestions, but I figured sure, why not.  The male had been recently been moved into a seldom-used holding pen while his females were giving birth.  It was shortly after this move that the symptom – lethargy, discomfort – began.   It seemed likely that the problem was with the enclosure.

Two steps into the exhibit, I saw something I didn’t like - pale flowers.  Bending down, I used the sleeve of my sweatshirt as a glove to grasp a thorn-studded stem, then pulled.  It was a nightshade, a toxic plant which can cause sickness, even death, if consumed, to say nothing of symptoms similar to what our guanaco was showing.  Of course, like most toxic plants it is pretty bitter, which, combined with the thorns on the stems and the undersides of the leaves, make it a pretty unappealing mouthful for any hungry animal.

Of course, as I stood back up, I saw right away that our wayward guanaco hadn’t had much in the way of choices.  With this yard being unused for so long, nightshade had completely taken over.  It literally carpeted the exhibit floor like grass.

There’s so much concern about how badly animals will damage plants in a zoo, but we should also worry about how much damage plants can do to animals – especially through ingestion.  Nightshade, jimsonweed, and other toxic plants can flourish in the right environment, and not all animals are savvy enough to avoid them.  It’s the responsibility of keepers to learn to identify the poisonous plants that occur where they work so they can be found and removed before their animals eat any.  It’s just as important to know about the trees and bushes that you feed animals as browse – what is safe, what isn’t.

Something may be safe for one species but harmful for others.  Red maple, for instance, is fine to feed to ruminants, but should not be fed to non-ruminant herbivores, such as horses.  Poison ivy may drive us crazy, but white-tailed deer can eat it just fine.  The safest course of action is also one of the simplest – if you don’t know what something is, don’t feed it out.

Also worth pointing out – it’s not enough to keep toxic plants out of your enclosures.  You also need to keep them off grounds entirely as much as possible.  That can reduce the risk of visitors pulling a plant from the ground and offering it to the animals as a snack.

We moved the male guanaco to a different, nightshade-free pen – the one advantage of his condition was that it made him a lot more tractable and manageable than he normally was.  After not too long, the bad stuff worked its way out of his system and he was back to his irascible, keeper-charging old-self.  During his recovery, we gave the holding yard the old Agent Orange treatment until there wasn’t a leaf of nightshade left.

I’m still not sure what convinced him that a salad of thorny, bad-tasting, sickening stuff was a good idea, or why he had continued to eat it.  Perhaps he was just curious.  Curiosity, as they say, killed the cat.  It might have almost done the guanaco in as well.