Zoos all over the world now regularly weigh animals under their care. How does one weigh a huge orangutan or a tiny tamarin? Well, training your critter to sit on a scale is the first part, and patience is the second part. Oh, and a nice treat as a reward is the last (and best part) as far as our subjects are concerned.
Why do you suppose we need weights, anyway? Well, non-human primates have the same tendency as human primates do to gain excess weight and develop chronic diseases as a result. And, geriatric animals tend to drop weight – making sure that we are on top of weight loss is very important. In addition, medication dosages are based on body weight, so to be sure that our animals are getting a correct dose is vital.
We have scales that are specially built to weigh the smallest to the largest animal in the zoo. Our orangutans have a special platform built on top of their scale that they sit on so that all body parts stay on the scale: when you have long arms, they need to be on the scale and not on the floor to get a proper weight. So, Rudi (pictured) is sitting on that bench on top of the scale. He and all of the other orangutans receive juice for sitting on that bench long enough for the keeper to read the weight, which is in “the brains” of the scale sitting outside the mesh. His current weight is 121 kilos, which is 266 pounds. This weight is recorded in our daily documentation which goes to the veterinary clinic for review.
Roberto is the Pied tamarin in the next photo, and he is one of our older fellows who we need to weigh frequently to be sure he doesn’t lose too many grams in any given week. He is trained to sit inside a small nestbox which is perched atop a gram scale. You’ll notice he is sticking his tongue out at his keeper…this is a tamarin insult and his equivalent of saying “I am the boss of you!” in monkey language. Once the treat of a fat, juicy wax worm was delivered, he stopped tongue flicking and swallowed his delicious prize. If he did lose weight, primate managers could propose a diet increase to bump him up again.
Weighing our animals is just one small part of excellent husbandry that takes place at the Houston Zoo, and our keepers take pride in making sure this is done regularly – and they always make it fun for monkeys and apes.