Why Aren’t All Crown Anoles Green? The Case of the Polymorphic Canopy Anole, Anolis cuvieri

Brown/Grey phase Anolis cuvieri, just awakened from a nap. Photo by Alejandro Sanchez.

Brown/Grey phase Anolis cuvieri, just awakened from a nap. Photo by Alejandro Sanchez.

Most arboreal anoles are green, and for a good reason: it’s hard to pick out a green lizard amidst green vegetation. Yet, some species are more subdued in their coloration, with browns or grays–e.g., Anolis luteogularis from Cuba or Anolis microtus from Costa Rica.

An interesting twist is provided by Cuvier’s anole, the crown-giant of Puerto Rico, in which a polymorphism exists in which most lizards are green, but some are brown-grey. We were reminded of this situation by Alejandro Sanchez, who sent the photo displayed above with the comment that it had been a long time since he’d seen one of these morphs. Contrast that with his spectacular photo of the more common green morph below.

Green Anolis cuvieri. Photo by Alejandro Sanchez.

Green Anolis cuvieri. Photo by Alejandro Sanchez.

Rivero in his epic Los Anfibios y Reptiles de Puerto Rico notes the polymorphism, but does not provide any explanation or discussion, and I am unaware of any other literature on this subject. Puerto Rican readers out there: what else do we know? Are they definitely different morphs? Someone once whispered in my ear he had seen brown ones turn green, but the only publication of which I’m aware to discuss this phenomenon, Rand and Andrews (1975), says they don’t. But that was based on a very small sample size. Does the gray/brown morph occur throughout the island? Any idea what it’s all about? Any difference in habitat use? As far as I’m aware, the adaptive significance of this polymorphism has never been studied.

About Jonathan Losos

Professor and Curator of Herpetology at the Museum of Comparative Zoology at Harvard University. I've spent my entire professional career studying anoles and have discovered that the more I learn about anoles, the more I realize I don't know.

6 thoughts on “Why Aren’t All Crown Anoles Green? The Case of the Polymorphic Canopy Anole, Anolis cuvieri

  1. I don’t think the grey ones turn green; but there are surely folks who could definitively address this. Juveniles are a (much brighter) shade of grey as well, & then (generally) turn bright green as they mature. The grey morph adults are a much duller shade, as shown in your picture and in this photo of a grey morph from a recent field trip.

    Also, here is a picture of a bright grey subadult A. cuvieri sleeping. This photo is courtesy my Ph.D. student, Kristin.

    Also

  2. I’ve seen the brown/gray ones at Mata de Platano and also in the forest near Mayaguez, but I was told by a graduate student at UPR that the gray morph is very rare. I’ve never seen the gray ones turn green, they just turn darker brown, but the gray ones did have small amounts of green on them. Here’s both morphs side by side from Mayaguez, both large adult males.

  3. About a year ago I photographed a brown A. curvieri near the center of the Rio Abajo Forest in Arecibo. The color was so dark that in the subdued light of the understory it looked like it was black. It was eating a taratula, a very unusual sight in itself.

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