The Common Basilisk, Basiliscus basiliscus, is also known as the Jesus Christ Lizard, due to its ability to move rapidly over the water surface. It can’t walk on water but it can run on it: an impressive sight as the lizard rears up and races along bipedally, resembling a small Velociraptor. This ability is due to the very long toes on the hind feet that are equipped with flaps of skin that catch tiny air bubbles and increase the surface tension of the water, thus keeping them afloat. Young basilisks can run 10-20 m over water, whereas adults will sink after a few meters. These lizards swim very well, as I discovered one night. I was stream-walking with ace herpetologist Twan Leenders, when a large lizard raced past me, leapt into the stream and completely submerged itself. I excitedly called to Twan, who already knew of this escape tactic. The basilisk cools off underwater and can remain somewhat torpid, fully submerged for up to 30 minutes. Generally they stay on the riverbanks and use the water only as an escape route.
Common Basilisks are indeed very common along the river’s edge everywhere at Finca Bellavista Community. If you climb up to the waterfall you should see several of these animals looking at you from the rocky banks, or racing off to hide. If you are lucky you might see one dash across a river pool. These large and agile lizards feed mostly on insects and other invertebrates, but adults also eat fish, smaller lizards, birds and small mammals on occasion. They also eat fruit and flowers.
Male basilisks have a size-based dominance hierarchy, and larger males inhibit breeding by younger males, which are reproductively mature by age 2 but usually do not breed until 3-4 years of age. Females are mature at just under 2 years of age. Females dig a hole and lay clutches of 2-18 eggs. Several clutches are laid during one year, in the wetter months. After digging the hole and depositing the eggs, the female fills the hole with soil, packing it down with her snout. There ends her parental care.
Young basilisks and females have a small crest on the head; very young animals lack crests (as in the photo opposite). Adult males have large crests on the head, trunk and tail. Common Basilisks are quite variable in color.
Males usually have a white stripe from eye to tail and a second stripe from nostril to shoulder. They all have transverse dark bands on a brownish background. Basilisks are active by day and sleep at night. They usually climb up trees or branches to sleep. I have read that they do not climb during the day, but the Finca basilisks beg to differ. I have had several different individuals climb up the tree into my house and lounge on my deck, a good 10 m up, in the afternoon.
One afternoon we were sitting on the couch in the open living room of El Fenix and my son Ian pointed at the tree, but before he could say anything a large basilisk leapt onto his shoulder! It was gone in a flash, over the side and onto another tree nearby.
My lounge lizards venture quite far from water and make themselves at home in the trees at any time. At night you can see small basilisks sleeping along the Red Trail, quite far from the water. I found the biggest basilisk I have seen asleep on a vertical trunk by the river. It was across a raging torrent so I didn’t get very good close up pictures, but you can at least see the crest on this fine adult male.
by Fiona A. Reid
owner of El Fenix treehouse and Sylvan Camp and Falls