This is the first summer together for Geyri and I. He came to live with me in September last year, and there was some effort needed to learn to keep the temp in his viv just right with the heat in the house. Different wattage of lights at the two ends of his vivarium make a heat gradient of about 82 at the cool end to about 100 at the hot end. (They need the high heat to be able to digest their food, since being cold blooded, they don’t make any of their own body heat. If they don’t have enough heat to bask and walk around in in their vivs, the digested food can literally rot in their little bellies and they will die.) But they also need to be able to get away from the heat if they feel the need by going to the cool end for a while, so having that temp gradient is critical to their healthy lives.
Vivarium, that’s a word some people don’t know. A terrarium is an artificially controlled environment where plants have their correct temps and humidity. A vivarium is basically the same thing, except that…..somebody lives in there.
So in the winter, in his controlled environment, instinct still told him that the other lizards in the big desert go into a semi sleep called brumation during the winter. They might come out and have a look around sometimes, might eat a small amount, and then go back to sleep. Some don’t come out at all and their keepers sometimes look down in their burrows now and then to make sure they haven’t….died. Brumation can go on for as much as 3 months. Uro keepers are bored during brumation. We put a little food out each day just in case they come out, but many days they just keep sleeping. Geyri mostly slept for about 2 months, then started coming out about once a week till it was time for his brumation to be over. Amazingly, their metabolism slows down to the point that most of them don’t lose any weight during the time they’re sleeping.
Instinct is an amazing thing. Wrens come back to the same yard to nest, salmon know where to go to spawn, and little Geyri knows how lizards are supposed to live in the hot, arid mountainous scrub desert of the Sahara.
Once he was done with brumation this spring, he would come wandering out about 10 or 11, once the heat got up in his viv. (Lights with heat are on from 8-8.) Just like the uros do in the big desert. But now, it’s the beginning of our summer heat here, and although Geyri is still in his controlled environment, he knows that lizards in a hot desert should go in their underground burrow in the heat of the afternoons.
So most mornings lately, he’s been coming out early, about 9. Basks and warms up a while, and then is ready to eat and bask some more. That’s what they do in their natural habitat. Then about 2, he goes down into his burrow.
Then about 6 or 6:30, he has been coming back out. The first day he really surprised me! He wandered out of his well-dug burrow and went to the piece of slate where he finds a lot of his food. He put his front feet up on the slate and gave me “a look,” like: Hey hooman, there’s supposed to be food here! Where’s the good food?
There was still some dried dandelion there and some half dried endive I hadn’t picked up yet. So he ate some dandelion and started on a piece of the endive while I quickly went to the fridge to get him some good fresh stuff with moisture. He munched on some of all of that and looked around a bit and went right back down in his burrow. Now I know I need to put out a second small amount of fresh food in the late afternoon, in case he decides he’s hungry again before he goes down in his burrow for the night.
They don’t drink water, since they live in an area where there is about 1” average of rain a year. They get all their moisture from the vegetation they eat, and in the wild that isn’t much. But they have evolved to hold moisture in their bodies and don’t need as much as a lizard of their size from another part of the world.
So Geyri’s never been to the Sahara, tho both his parents came from there. But built into his brain is the instinct to know exactly how a big desert lizard should live. Fascinating. Nature is always fascinating, and sometimes we get an up close look at it and get to understand how and why it works. Geyri has taught me a lot about lizard instinct.
If you’ve ever thought lizards don’t have personalities, I can say for sure that they do.