Water anole from the Osa Peninsula, Costa Rica (Photo by Lindsey Swierk)
Written by Andrés Rojo:
The water anole (Anolis aquaticus) is a Costa Rican anole that changes color and pattern in different microhabitats as a form of camouflage to avoid detection by their predators, which include birds like motmots and kingfishers. Because of its body color complexity and rapid color changes, water anoles are great study organisms to use when examining how animal camouflage, social signaling, and visual perception interact.
My research project was inspired by Dr. Lindsey Swierk and her lab’s work on water anole color change and camouflage. I joined the Swierk lab as an undergraduate in February of 2021, as I was interested in tropical ecology and animal behavior. I am also a photo hobbyist and experiment with color and full spectrum photography. Dr. Swierk thought that I would be a good fit with the research team studying water anole colors and patterns. When she told me about it, I was motivated by my enthusiasm for photography and wildlife research to take on the project, especially the idea that I could modify research-grade photos to model how animals see one another.
An example color cloud map showing the colors of a water anole (gray) and its substrate (red) as seen through an avian visual system. The X axis represents a green-to-red progression of colors, and the Y axis represents yellow-to-blue colors. Water anoles do not have UV body colors in the regions measured (dorsal and lateral surfaces). Darker tones indicate more pixels of colors at that location within chromaticity space.
Dr. Swierk and I decided to test whether the body coloration of A. aquaticus would be perceived differently by the visual systems of water anoles’ predators and their conspecifics. We used ImageJ and the micaToolbox (QCPA) to model the two visual systems and apply them to each photo taken in the field. The anole and substrate photos were converted into color maps, which could be compared to determine how much the color of the anole overlapped with the color of the substrate in the visual systems of predators and conspecifics – a measure of conspicuousness of anoles according to both visual systems.
A comparison of body color – background color overlap of water anoles as seen through bird and anole visual models, including males (blue) and females (gold).
Although we found no significant difference in how camouflaged A. aquaticus were perceived by the visual systems of predators and conspecifics, our results suggested that males more consistently color matched their microhabitats compared to females and that females were less likely to color match their backgrounds in their lighter phase, suggesting a sex difference in preferred conspicuity in more exposed habitats. These could present topics for future research into how anoles use color camouflage to avoid being detected by predators.
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Theresa Monaghan
Very interesting. I am wondering if we will be able to save any Anolis carolinensis in suburban areas that host TNR free cat colonies. In the space of a year my neighbor started feeding around 20 feral cats. We have since neutered or spayed them but during that time my reptiles disappeared. Any thoughts?