In spring and summer in Texas, we see lizards everywhere we look.  They’re climbing on the trees, crawling on the ground, and running around the walls of our houses.  If you watch a lizard for a few minutes in the summer, you’ll probably see it catching an insect to eat, or chasing another lizard out of its territory, or sitting in the shade to stay cool.

But in the fall and winter when the temperature drops, we don’t see many lizards anymore.  What are they doing when the cold wind and rain come?  The answer is, they’re not doing very much!  Lizards are a type of animal called ectotherms, which means that their body temperature is the same as the environment around them.  So when the air outside is cold, lizards are cold too.  On the other hand, humans (along with other mammals and birds) are endotherms, which means that our internal functions keep our bodies at a warm temperature no matter what the weather is outside.

When lizards are cold, they don’t need to eat very much to stay alive, so they don’t need to be active.  Instead, they try to find a warm place to hide.  They might burrow under leaves, or dig a hole in the soil, or find a hole in a tree trunk.  In general, lizards will sit very still in these safe places and wait for warmer weather, when they will come out and sit in the sun to warm themselves.  Once they’re warm, they’ll start running after food and chasing other lizards again!

For the scientists in the Lizard Lab, we usually work inside during the winter too. Since it’s harder to find lizards outside, we spend this time looking at lizard cells under a microscope, looking for patterns in our measurements from the summer, and writing papers about our new discoveries.  There’s always important work to do when you’re a scientist!