Here’s an excerpt from a children’s book about lizards that I am working on between other things – started this one back in 2002.
You have just walked out of your summer cabin in the mountains to enjoy the early morning sun. On fallen tree trunk near your cabin, you see something moving up and down. It is a lizard that looks like it doing its morning exercises, doing push-ups on the tree trunk. Now what, you wonder, is going on. The lizard stops doing push-ups when you stand still and flattens itself against the sunny side of the tree trunk. Well now, you think, the lizard is also enjoying the morning sun, that I can understand – but doing push-ups? You sit on the porch to enjoy the morning sun yourself, and you wonder about those push-ups. Why was that lizard doing push-ups? Do lizards need their morning exercise too, or were those really push-ups? Maybe the lizard was looking for food, or maybe it was trying to scare me away or maybe it was checking for other lizards or for something that might be looking for a lizard for breakfast. You look over at the tree trunk and notice the lizard moving about on the ground. Now, what is the lizard doing? For that matter, what do lizards do and why do they do what they do? I wonder if I watched that lizard all day what I would see. And with that, you get up and go back into the cabin. You won’t be able to watch a lizard all day today because you are going to be fishing and it’s time to get your fishing gear and head for the lake.
If you had spent the day watching the lizard, what might you have seen? On the planet earth, there are about 3,000 different kinds, species, of lizards. Most of those live in tropical areas of the world. There are about 115 species of lizards in the United States. A few more than half of those are in the western half of the country. Lizards are found in all kinds of places from high in the Rocky Mountains to the swamps of Georgia and Florida. Some lizards swim in the ocean, and there are lizards that swim in the sand. Some lizards burrow in the ground, and others burrow through the grass. Some lizards live in cracks in rocks in the desert and others glide from tree to tree in the tropical rainforest.
So almost anywhere you might be, if you look around real hard, you have a good chance of finding a lizard. But if you want to discover what lizards really do, you will need to spend a bit more than a day following one to find out. Some people who are very interested in lizards have spent their lifetimes trying to discover what lizards do. Luckily for us, the serious lizard watchers, who call themselves herpetologists, write books and articles about what different kinds of lizards do. By reading those books and articles, we can learn a lot about lizards without spending our whole lives watching them. But – if you do spend some time watching a lizard, you too can learn something new about what they do.
Now let’s talk about what kinds of things that herpetologists know about what lizards do. Lizards do a lot of the same kinds of things that we do. They sleep; they eat; they disagree with one another, and they make baby lizards. Many kinds of lizards spend a lot of time sitting in the sun. No, they’re not working on their tan, they need to sit in the sun so that they can do all of the other things they do. You see, lizards are dependent on the sun and the temperature around them to be warm. We, on the other hand, make lots of heat inside our bodies and don’t depend on how warm the air around us is to be warm enough to do things. Both lizards and people make heat inside their bodies as part of being alive. People make lots of heat and have ways to keep it inside. Lizards don’t keep their inside heat very well. So, when it gets cool, most lizards slow way down and if it gets very cold, they stop. Because lizards need outside heat to be warm enough to do things, people have thought that they must be cooler than us and have called them cold-blooded. Lizards aren’t really cold at all. In fact some lizards, like one called the desert iguana that lives in some of the deserts of the southwest have temperatures that are warmer than ours when they are going about their normal business. Some other lizards live in tropical areas or spend most of their time in shady places. Those lizards may be cooler than us. Tropical and shade-living lizards don’t spend much time sitting in the sun. Some lizards that burrow may never see the sun at all, so they live in places where the air or the soil is always warm enough for them to do whatever they do. Getting warm by sitting in the sun is called basking. Lizards that bask can live in places where the air is cool and may even freeze in the winter. Sun-loving lizards are called heliotherms, which means sun warmers. They get warm enough to do their thing by basking even when the air or soil is not very warm.
So, to do all of the other things that they need to do, lizards have first to be warm enough. Lizards have to be careful, however, not to get too warm. Just like us, if lizards get too warm, they can get sick and die. The business of staying the right temperature, as it turns out, plays a big role in what other things lizards do and when and how they do them. Lizards, like us, do different things in the spring and summer than they do in the fall and winter unless they live in a tropical place. In tropical places, lizards do different things when it is raining than when it is not.
You see, most tropical areas don’t have hot and cold and in-between seasons, but have dry and rainy seasons or wetter and less wet seasons. Many lizards do their thing during the day. A few do their thing at night. Some don’t care if it’s night or day. Well then, we know, from reading about and watching them, that lizards do whatever they do if they are warm enough, but not too warm. They do different things at different times of the day and different things in different parts of the year. Just think about all the different times and seasons there can be in different places. Whew, no wonder some people have spent their whole lives trying to find out what lizards do.