2018 Utila Research Update

Conservation approaches, population monitoring, and nesting ecology of the Critically Endangered Útila Spiny-tailed Iguana Ctenosaura bakeri on the island of Útila, Honduras

Report submitted by Daisy Maryon (Kanahau Útila Research and Conservation Facility) and David Lee (University of South Wales).

December 2017 – September 2018

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A male Útila Spiny-tailed Iguana in white mangrove leaf litter. Photo by Tom Brown.

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Winning photo in the ‘Best Iguana’ category for the Eyes of Útila photography competition. Photo by Blake Hernandez.
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Daisy Maryon (left) with Blake Hernandez, the winner of the ‘Best Iguana” category for the Eyes of Útila photo competition. Photo by Andrea Martinez.

Our field guide training is progressing well; we are continuing to provide an alternative income to our first field guide (Nahun Molina), and this year we were also able to pay and train a second guide, Landito Ayala. Beyond thier work as field guides, Landito and Nahun performed conservation outreach through informal talks with the local community and social media posts.

“Iggy” the recycling iguana float for the Útila Carnival 2018 that was made completely from plastic trash collected on the beach. Photo by Daisy Maryon.

For the annual Útila carnival in July, the Kanahau team made a mobile “Recycling Swamper” float made from trash found on Útila beaches. The float was part of the parade and people could place any recyclable material inside the Recycling Swamper as we moved through town. The float was featured on national news stations covering the carnivals and is now part of the “Promodias Video”, a promotional video for island tourism. The float has now been used for other events encouraging people to recycle throughout the year, and tourists have been taking selfies with the float and using the “#SaveTheSwamper” hashtag to further the campaign message.

Capture-Mark-Recapture and Distance Sampling Population Study. Our study caught its 1,000th Ctenosaura bakeri this year, bringing our total captures to 1,054 animals. Each iguana is marked by using a nape bead or PIT tag allowing identification over the years. This August, we recaptured iguana number four, which is a female first caught in 2011 and is likely between 9–12 years old, giving us some fantastic longevity data for this species. Distance sampling has been used throughout our project to estimate population size. This year we were able to visit a new site on the western side of the island to sample the iguana population which brings our total to 10 different survey sites and 32 transects across the island. We were also able to shortlist areas that may be suitable for a new protected area for C. bakeri and the other endemic species of Útila. All of this information was added to the IUCN Red List assessment for the species which was published in July and confirmed the Critically Endangered status of C. bakeri.

Nest Ecology. We discovered a new nesting ground for this year, in an area of the island previously thought to be unsuitable habitat for C. bakeri as it is surrounded by hardwood forests and agricultural land. One camera trap set up to record nesting behaviours within the current nature reserve (Turtle Harbor Wildlife Refuge) was unfortunately stolen, though other cameras gave us more insight on predator pressure facing nesting C. bakeri, regularly showing family groups of non-native racoons on the images.

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School children and Kanahau researchers on a photography field trip looking for Útila Spiny-tailed iguanas. Photo by Leslie Dean.

This year we discovered a new nesting beach for C. bakeri in the north of Útila that we previously thought was unsuitable due to its surrounding of hardwood forest and agricultural land. The area known as Pumpkin Hill has been undergoing rapid development over the past year with creation of a new road and many new housing plots. The presence of a hatchling C. bakeri and a small number of adult male sightings raises the question of whether a small population has always existed in this area and is now more visible due to the deforestation of the site, or whether iguanas are moving from other areas due to other factors such as unsuitable nesting grounds elsewhere. Many C. similis are also found in this habitat and it may be possible that the bakeri seen are hybrids. Genetic analysis awaits at the University of South Wales to answer this question this autumn.

Hybridization Genetic Analysis. 247 new Ctenosaura bakeri and 65 Ctenosaura similis were captured throughout 2016–2018. This summer, DNA was extracted from eight of these samples in the lab at the University of South Wales. DNA extraction will continue with the help of undergraduate students at the University and extracted DNA will be sent for sequencing this autumn to receive results of hybridization within the population. A further 40 C. bakeri blood samples were taken for phthalates analysis by veterinary students at the Cummings School of Veterinary Medicine at Tufts University, Massachusetts.

Future. In the future, we intend to expand the education program by employing a permanent team member to expand community outreach by planning more awareness events involving the iguanas, and create conservation awareness posters and signs to explain the conservation status and promote anti-poaching of the iguanas.

The original plan for the project was to have one intern act as the environmental education officer for the entire period from February to October. However, in 2018, we had one student from UNAH who carried out her internship for university credit for two months, and then one local island intern who started work in July. As such there was a lull between the two interns. It became clear to us that a full-time member of staff is required to implement the education program and have an intern to assist. This will program will continue work alongside the population research monitoring project.

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Útila Spiny-tailed Iguana number 4 — a female that was first caught in 2011 and recaptured August 2018. Photo by Daisy Maryon.
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The Kanahau iguana field team and the 1000th Iguana captured. Photo by Junior Williams.