2019 Roatán Spiny-tailed Iguana Report
Monitoring an Endangered Iguana and Cultivating the Next Generation of Researchers and Managers
Stesha Pasachnik (Fort Worth Zoo), Daisy Maryon (University of South Wales), Ashley Goode (USDA), Susannah French (Utah State University)
Overview and Objectives.
In order to create a sustainable monitoring program, as well as foster the next generation of iguana researchers and managers, we offer a yearly workshop in which students and interested members of government/NGOs obtain intensive training in the field, while collecting vital natural history data for this long-term project. Workshop participants gain experience in all basic techniques of iguana research and the workshops are specifically catered to the participants’ needs for their programs and interests for study or management. Participants are also able to gain experience working as a team to conduct independent studies, potentially leading to publications. These projects provide an opportunity to analyze and document the vegetation of Roatán and diet of C. oedirhina, evaluate reproductive state, condition, and health, run flight distance and behavioral trials, use transect surveys, collaborate with local conservation organizations (e.g. Kanahau), provide information to the community through outreach activates, and prepare IUCN Red List assessments. Data collected during these workshops is continually added to the life history table for this species in order to inform local management strategies. This is now the longest running continual natural history study of a ctenosaur iguana and we are hopeful that the information gained here can translate to other species with similar life histories.
Outcomes and Impacts
In order to continue monitoring C. oedirhina and keep a visible presence on Roatán , as well as provide training, we held our ten-day workshop which focused on field techniques and general conservation and research concepts. This year we also expanded into laboratory techniques investigating energy metabolites in the blood and oxidative stress status in individuals and ultrasound to assess reproductive status of females. The workshop included five participants from four different countries and one graduate student from Utah State University, interested in pursuing conservation research. Participants included an intern with the Honduran Fundación para la Protección de Lancetilla, Punta Sal y Texiguat (PROLANSATE), a field officer for the National Trust for the Cayman Islands’ Blue Iguana Program, a conservation officer with Anguilla National Trust, a laboratory assistant at the National Autonomous University of Honduras in Sula Valley (UNAH-VS) with interest in studying iguanas on the mainland of Honduras, and a laboratory assistant at the Instituto Tecnológico de Santo Domingo (INTEC), working on iguana genetics in the Dominican Republic. After assessing the varied backgrounds and interests of the participants, we designed the field and lecture components of the workshop to cater to their interests and needs. By training participants, we help to build capacity in Central America and the Caribbean for those just beginning their research careers and those already involved in iguana projects and management. This opportunity also allows individuals to network with others in the field and we all benefit from exchanging ideas and experiences from other regions and programs. The participants came with diverse backgrounds in fieldwork, research, education, and career paths, but all were able to learn new monitoring and research techniques. The participant from the Cayman Islands commented that he enjoyed gaining knowledge that he can apply to the Blue Iguana conservation action plan. The participant from Anguilla said that he was able to learn new capture techniques to use in their iguana program. One of the Honduran students was able to design a study, that he will conduct on C. similis on the mainland, using the techniques he learned at the workshop. Due to our expansion into blood chemistry analyses we were able to teach the participants an additional level of techniques that the participant from the Dominican Republic was particularly excited about. This new avenue will open to workshops up to people with more varied interests.
This year marks our ninth year of intensive mark-recapture research. Sixty-five new iguanas were captured and 33 were recaptured across our sites, including the new privately-owned site initially surveyed last year. Over the course of this study from 2010 onward, we have marked 1146 iguanas across Roatán and have seen significant fluctuations in population size and structure. This year we recaptured individuals first marked in 2010 providing important longevity information. We were also able to use our data to demonstrate the impact that changes in cat control methods have had in the newest study site. Continued monitoring of demographic trends is vital to proper management of this species. In addition, maintaining a presence on the island helps to reinforce the protection of the iguanas, especially at study sites where hunting intrusions occur. The captured and tagged iguanas provide important data for growth and survival analyses. These demographic data provide the first long-term monitoring effort for this genus and can thus be used as a model for other species within the genus.
Based on two years of reproductive assessments via ultrasound and physiological indicators of energetics and stress, we have started to identify important energetic indicators for reproduction. Specifically, we see that reproducing females have elevated energy metabolites in the blood and that these are directly related to stage of reproduction as well as clutch size. We also show significant variation in glucose across sites and elevated oxidative stress in males at two sites in close proximity. Moving forward this year it will be important to investigate potential site-level factors that are leading to these effects. Finally, with ultrasonography we can now determine reproductive rates across populations. Putting this all together we will eventually be able to tie physiological indicators critical for reproduction to reproductive rates and ultimately to population fluctuations.
We plan to continue these workshops to ensure that protection and monitoring of this species persists, while building capacity in iguana range countries and broadening our research goals. We will continue to complete IUCN Red List Assessments and include additional smaller projects, similar to our on-going dietary study. This will allow participants to experience managing data collection, analyzing data, and publishing short articles. Dr. Susannah French’s newly formed collaboration allows participants to be exposed to new techniques, focused on physiological health metrics using biological samples, including energy metabolites and stress markers in the blood. This also provides participants with hands on training in laboratory procedures and analysis that can be readily adapted for field use. Lastly, due to our discovery of an invasive Ctenosaura bakeri population on a small cay off Roatán we will focus monitoring and management efforts on this population to reduce risk of hybridization and genetic swamping. We will continue to work with the Honduran government to manage this issue.