Review of radio transmitter attachment methods for West Indian rock iguanas (genus Cyclura)

Abstract

Methods for attaching radio transmitters to rock iguanas (genus Cyclura ) are described and compared based on signal range, longevity of attachment, and potential disturbance to animal behavior or health. Case studies are described for all instances of internal implantation, ingestion, and external attachment of transmitters for which data are available. Signal range did not differ dramatically between attachment methods, but did differ between transmitter models and habitats in which iguanas were tracked. Only transmitters with coiled antennas showed a dramatic reduction in signal range. Longevity of transmitter attachment varied greatly among attachment methods, and was greatest for implantation, least for ingestion, and intermediate for external methods. Internal placement of transmitters via ingestion or implantation was advantageous in having no external apparatus to snag on vegetation or rocks. However, ingestion yielded less than one week of data, and implantation required costly, potentially stressful surgery. External attachment methods, including suturing of transmitters, mounting with adhesive, and harnesses or collars with breakaway mechanisms, entailed low cost and low risk, but were less reliable for long-term attachment. Harnesses or belts that lacked breakaway mechanisms entailed higher risk, because iguanas may suffer injury or death if not monitored frequently and recaptured for removal of attachment devices. In many studies, iguanas successfully mated, nested, and appeared to behave normally with transmitters attached by various methods. However, further research is needed to determine how different attachment methods affect the health, behavior, and survivorship of iguanas, particularly in smaller species and juveniles, which are more susceptible to predation.