Summer is a busy time at the Oakland Zoo and the Wayne and Gladys Valley Children’s Zoo is no exception! You may have noticed the number of Aldabra Tortoises shrinks every summer and returns every winter. At the beginning of every summer, we move the male tortoises to a large grassy holding area for a few months for two reasons. First, the turf just needs a break! Grass is the primary diet for these guys and they graze it down to almost nothing, so in the summer we give the lawn a break to fertilize and reseed. Second, there is a theory in the reptile world that “absence makes the heart grow fonder” and many herpetologists believe that separating males and females for a few months increases the chances of them breeding when they finally get back together.
Great idea, but….how do you move a 500 pound tortoise? I have to admit that this is not one of my favorite jobs. First you have to get them out of their favorite mud wallow, not an easy task. By the time we finally get them out of the mud, we keepers usually look like the swamp monster! Then, we have to carry the slippery tortoise across the yard, out the gate and load them into a truck. It takes at least six people to lift a tortoise onto the back of the pick-up truck and it’s not like they sit still once they are there. Five keepers then have to sit on the back of the moving truck with him and try to keep him from climbing out, and believe me they are even stronger than they look!
For the last year, the keepers have been working on a training program with the tortoises using the same positive reinforcement techniques that we use with many of the other zoo animals. It’s pretty simple; the tortoises have a 10 inch square of plywood each painted with their own color called their “target.” When they touch the target, they get a piece of carrot. Who would have guessed that such a simple behavior would be so powerful!
This year, when it was time to move Gus, he was happily settled into his giant mud wallow with his two favorite girls. I must admit, I groaned a bit at the prospect of having to extract him. But, the power of positive reinforcement prevailed! As soon as Gus saw his red target, he got up and followed the keepers out of the mud wallow and all the way across the yard to the gate of his own free will! He even let us rinse the mud off him with the hose! Granted we still had to lift him into the truck, but it was a lot easier on our backs because he was so much closer! And, we did still get a bit muddy, but at least we were still recognizable as keepers, not the swamp monster. The best part is that Gus CHOSE to move! We didn’t force him; he cooperated with his keepers based on his relationship with them and the positive reinforcement. In fact, we are continuing to use these techniques to train other behaviors such as weighing, nail trims and blood draws. Training tortoises is truly progressive animal management, which is something the Oakland Zoo excels at! And, Gus is just as happy in his summer home as he is in his winter home!