This is a guest blog written by Jordan Bush, edited by Felicity Muth. Jordan Bush is a graduate student at the University of Tennessee, where she is investigating how invasive lizards disrupt the social behaviors of native species.

 

I recently went to my very first drive-in movie theatre to see “The Secret Life of Pets”. While my inner child delighted in the hijinks of the fuzzy protagonists, the scientist in me was a little taken aback.  Why were all the snakes and lizards in the movie villains?  And not even major villains, they were nameless henchmen that got big rocks dropped on their heads! I study lizards for a living, so I am a little biased, but I think that this vilification of reptiles is highly undeserved. As proof that our scaly friends deserve our love and admiration just as much as their furry brethren, I give you these three scientific findings showcasing the beauty and complexity of reptile behaviors.

But reptiles are big and scary, you say.  I agree, anacondas are large, and alligators are toothier than I personally am comfortable with.  But did you know that even the biggest, scariest reptiles love their mammas? Mother Nile crocodiles (Crocodylus niloticus) ferry their newly hatched young in their mouths from the nest to the relative safety of the water and guard them for the next several weeks. For a long time, this ferrying behavior was mistaken for cannibalism, as the observing researchers didn’t think that something with scales could exhibit maternal instincts. Yet in reality, most species of crocodile exhibit some form of parental care. Recently, a group of French researchers (Chabert et al. 2015) set out to study the communication between crocodile mothers and their young. To do this, they grabbed a bunch of baby alligators, caimans, and crocodiles and recorded their “Help Mom, a predator’s got me!” cries.  They found that older (i.e. larger) juveniles had lower pitched distress calls than younger individuals.  The researchers then played the calls back to the mothers of these animals to see how they reacted.  Most crocodilian mothers investigated the younger distress calls but not the older ones, indicating that mothers modify their level of parental care based on the age of the young. 

Crocodiles are extremely caring towards their young. Credit: Tambako The Jaguar Flickr (CC BY-ND 2.0)

But reptiles are boring, you say, they just don’t do very much. I hate to say this, but for a long time scientists agreed with you. Even into the 1970’s, reptile biologists were having to remind people that:

Careless, stereotyping comments that pose ‘mammals as active agile creatures, and reptiles as sluggish sprawlers’ should have no place in scientific discourse. Those of us who have witnessed the speed of a basilisk running bipedally on water, and who have also been bored by a lion lounging on its belly all day, know how fatuous such characterizations are. (Burghardt 1977).

We now know that, while reptiles often spend large amounts of time basking in the sun, they can still swim, run, jump, climb, dance, and glide with the best of them. Some reptiles even play! In 1996, Gordon Burghardt and colleagues performed the first official study of play behavior in a non-avian reptile. The study focused on Pigface, a Nile soft-shelled turtle living at the National Zoo at the time. The zookeepers were worried about Pigface, who was badly scratching himself in a form of self-mutilation, common in bored or stressed captive animals. 

Soft-shelled turtles suffer in environments lacking enrichment. Credit: Jordan Bush

To help him, the zookeepers introduced enrichment objects into his enclosure to give him something to do. Burghardt’s group characterized Pigface’s interactions with the objects and created an energy budget to describe the turtle’s typical day. They found that Pigface did indeed play with his new “toys”, with his favorite game being a daily tug-of-war with his keepers over a garden hose. He also liked nosing a basketball around the enclosure, bouncing a hula-hoop through the water, and positioning the water hose so that it sprayed him in the face. This research was surprising at the time, as not only was it the first official record of a playful reptile (and a turtle, of all things!), but it also indicated that Pigface spent almost twice as much time playing than even young mammals typically do. Since then, researchers have discovered play behavior in other species, including other turtle species and crocodiles. 

Video Credit: Gordon Burghardt, with permission. 

 

Many reptiles have behavior that is much more intricate than previously thought. For example, for a long time people assumed that lizards change colors as a form of camouflage, a conjecture that recently manifested itself in the chameleon Pascal from the Disney movie “Tangled”. And yet scientists now know that chameleon color changes have nothing to do with crypsis and everything to do with communication.  The combination of chameleon’s bright patterns and their ability to rapidly change colors means that they can pack a lot of information into their visual signals. In a recent paper published in the journal Biology Letters, researchers from Arizona State University attempted to understand how male veiled chameleons (Chamaeleo calyptratus) use color changes during aggressive encounters (Ligon and McGraw 2013). To do this, they recorded fights between veiled chameleons, recolored the images to represent a “chameleon’s eye view”, and compared these measures to aggressive behavior observed during the contests. They found that different body regions seemed to signal different pieces of information: stripe color was predictive of motivation (i.e., which lizards wanted to win the most), while head color was predictive of fighting ability (i.e., which lizards were best able to win). These results demonstrate the complexity of chameleon visual communication, where everything from color, pattern, and (apparently) body region can all communicate different pieces of information to a discerning eye.

Chameleons do not change color to camouflage, but instead to communicate. Credit: Todd Pierson

So, while I do not recommend that you go out and hug the nearest snake (indeed, most snakes would not like that), I do believe that everyone should learn to understand and appreciate them. Reptiles are smart, complex animals that form an important and dynamic part of the animal kingdom. So the next time you see a lizard, snake, or turtle, take a closer look. They might surprise you.   

 

 

References

Burghardt, G. M. (1977). Of iguanas and dinosaurs: Social behavior and communication in neonate reptiles. American Zoologist17(1), 177-190.

Burghardt, G. M., Ward, B., & Rosscoe, R. (1996). Problem of reptile play: Environmental enrichment and play behavior in a captive Nile soft‐shelled turtle, Trionyx triunguisZoo Biology15(3), 223-238.

Chabert, T., A. Colin, T. Aubin, V. Shacks, S. L. Bourquin, R. M. Elsey, J. G. Acosta, and N. Mathevon. (2015) Size does matter: crocodile mothers react more to the voice of smaller offspring. Scientific reports, 5, 5547. doi:10.1038/srep15547

Ligon, R. A., & McGraw, K. J. (2013). Chameleons communicate with complex colour changes during contests: different body regions convey different information. Biology letters9(6), 20130892.