Thesis Title

Correlation of Serum and Fecal Estradiol, Progesterone, and Testosterone in Three Species of Captive West Indian Rock Iguanas

Date of Graduation

Spring 2006


Master of Natural and Applied Science in Agriculture


College of Agriculture

Committee Chair

Dennis Schmitt


Over the past century, wild and captive populations of West Indian rock iguanas have been declining and some are facing extinction. Currently, little is known about their reproductive biology and there have been difficulties associated with captive reproduction. Noninvasive methods of monitoring fecal steroid metabolites have provided valuable reproductive information in other species of reptiles. This study used fecal and serum samples from 4 Grand Cayman blue iguanas, Cyclura nubila lewisi (2 females and 2 males), 3 Jamaican iguanas, Cyclura collei, (2 females and 1 male), and 2 female rhinoceros iguanas, Cyclura cornuta, all from the Indianapolis Zoo. The fecal and serum samples were used to validate estradiol, progesterone, and testosterone radioimmunoassays (RIAs). Using an RIA, testosterone values were determined for males and estradiol and progesterone values were determined for females. There was a significant correlation between serum and fecal progesterone in both C. collei females (p=0.009 and p=0.003), estradiol in 1 C. collei, 1 C. lewisi, and 1 cornuta (p=0.014, p=0.012, and p=0.005, respectively), and testosterone in 1 C. lewisi (p=0.015). Low levels of correlation between fecal and serum hormones may be influenced by diet, captivity, age, reproductive history, temperature, and gut passage time. The validation of fecal and serum steroid hormone RIAs indicates that it is possible to monitor steroid hormone levels in captive West Indian rock iguanas and could lead to more successful captive reproduction efforts.


estradiol, progesterone, testosterone, iguana, assay

Subject Categories



© Scotti A. Erickson