Emma Higgins presenting her work at Island Biology 2019

The third meeting of the nascent Society for Island Biology took place recently in stunning La Reunion in the western Indian Ocean. Conference goers were treated to a wonderful venue at the Université de La Réunion in St. Denis, whose campus looks out down the gentle slope to the open sea. Four hundred attendees from around the world reinforced what we already knew— that island biology as a study attracts a large number of researchers from very diverse fields of study. The conference organizers also are leading the way on making our meetings in remote locations more responsible; using live streaming of the sessions meant that some interested scientists could skip the travel and stay home to watch the sessions. But the real asset was that the organizers calculated the air travel carbon footprint for all attendees, finding that ~30 hectares of forest would need to be planted to offset the carbon emissions. Happily, that is exactly what they did! The conference organizers and hosts, in partnership with communities and other organizations, committed to reforesting exactly that amount in La Réunion and Mauritius.

OK, now on to the anoles! Well, given the remoteness of the meeting location (nearly the antipode of the Caribbean*) perhaps it is not too surprising that few anologists attended. But I am happy to report that Emma Higgins did, and gave an excellent presentation on her work with anoles on the island of Utila, one of the Honduran Bay Islands.

Emma is a 3rd year PhD student in Adam Algar’s lab at the University of Nottingham, where her thesis is focused on using emerging technology to study lizard thermal biology under changing conditions (think development, climate change, and species introductions). When I say using emerging technology, I mean using #allthetech; Emma uses 3D printing, drones fitted with thermal cameras, Sentinel satellites, and LIDAR to generate her data! Her motivation follows from asking what factors control the abundance, distribution, and microhabitat of anoles on Utila, and whether these variables might be better estimated at extremely fine scales using emerging technology.

A bit of background, there are four species of anoles on Utila, including the endemics A. bicaorum and A. utilensis. An additional native species is A. sericeus, which also occurs elsewhere in the Bay Islands as well as on the mainland. The fourth species is everyone’s favorite— A. sagrei! Utila has experienced a surge of development in the last 10 years, with new roads and development going up faster than conservationists can keep track of. This is a major threat to the island wildlife, which includes an endemic iguana known as The Swamper (Ctenosaura bakeri) which favors the dwindling mangrove forests.

Emma’s work involves collecting data both at anole-level as well as above the canopy. She uses a DJI Phantom 4 drone platform fitted with a near-infrared camera to estimate a normalized difference vegetation index (NDVI, a measure of “greenness”) of the forest canopy across habitats, and found that just NDVI explains 28% of the spatial heterogeneity of lizard operative temperatures (in a mixed-model framework). This suggests that her drone can identify suitable thermal environments for lizards from above the canopy. I should mention that her resolution here is 4cm/pixel! She plans to zoom out to space and test whether similar imagery from the Sentinel 2 satellite will also be useful.  Below the canopy, Emma is using LIDAR to simultaneously conduct forest shade modeling (for super fine-scale temporal variation in thermal microhabitat). LIDAR also detects perch availability, as it detects tree trunks very well. Emma also uses 3D printing to produce hundreds of anole models, each fitted with an iButton® temperature recorder and placed on perches in the forest. Each lizard print takes 52 minutes, so Emma ended up taking the printer to her flat to print 24/7 in preparation for her field season!

I should mention that Emma was joined at the conference by two other excellent scientists— lab mate Vanessa Cutts and fellow Utila lizard biologist Daisy Maryon, both of whom won awards for their posters at the conference!

Stay tuned for the announcement for the 2022 Island Biology meeting, to be held on either Mallorca in the Balearic Islands or Wellington, New Zealand. Also stay tuned for Emma’s results; we look forward to hearing more about her work!

Graham Reynolds
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