Long-term trends in the demography of the Allen Cays Rock Iguana (Cyclura cychlura inornata): Human disturbance and density-dependent effects John B. Iverson a, *, Sarah J. Converse b,1 , Geoffrey R. Smith c , Jennifer M. Valiulis d a Department of Biology, Earlham College, Richmond, IN 47374-4095, USA b Department of Fishery and Wildlife Biology, Colorado State University, Fort Collins, CO 80523-1474, USA c Department of Biology, Denison University, Granville, OH 43023, USA d Department of Biology, Colorado State University, Fort Collins, CO 80523-1474, USA ARTICLE INFO Article history: Received 23 December 2005 Received in revised form 16 April 2006 Accepted 18 April 2006 Available online 21 June 2006 Keywords: Population growth Survival Tourist feeding Carrying capacity Relocation Lizard ABSTRACT Allen Cays Rock Iguanas (Cyclura cychlura inornata) are native to two small islets (Leaf and U Cay) in the north-central Bahamas. These populations were nearly extirpated in the early 1900s because of heavy hunting pressure (for food), but increased to a total of ca. 150 lizards in 1970, and now number over 500 (not including juveniles). Over the past several decades poaching has declined, but tourist visitation (including nearly daily supplemental feeding of iguanas) has increased. To examine human impacts on the demography of these igua- nas, survival, population growth rates, and population sizes for subadult and adult (>25 cm snout-vent length) males and females on the two cays were estimated based on mark–recapture data collected over a 25-year period (1980–2004). As predicted, annual sur- vival probability was higher on U Cay (with less human visitation) than on Leaf Cay, was higher in females than in males (which are bolder), and exhibited a declining trend. Both populations more than doubled during this study, but population growth rates declined to near zero in recent years. These data reflect the importance of human impacts, but also suggest that the populations may be nearing carrying capacity. The rapid population growth observed on these cays, and that seen for several other translocated iguana popu- lations, suggest that if unnatural causes of mortality are reduced or eliminated, island pop- ulations of iguanas are capable of rapid recovery. The inexpensive establishment of assurance colonies on undisturbed ‘‘islands’’ should be considered for any comprehensive management plan for endangered species of iguanas. Ó 2006 Elsevier Ltd. All rights reserved. 1. Introduction As remote locations become more accessible, and as rates of human visitation to remote locales increase, populations of threatened or endangered animals and plants (as well as some healthy populations) face new threats and challenges. For example, increased interactions with humans, often as a result of increased tourism, have been shown to affect a range 0006-3207/$ - see front matter Ó 2006 Elsevier Ltd. All rights reserved. doi:10.1016/j.biocon.2006.04.022 * Corresponding author: Tel.: +1 765 983 1405; fax: +1 765 983 1497. E-mail addresses: johni@earlham.edu (J.B. Iverson), sconverse@usgs.gov (S.J. Converse), smithg@denison.edu (G.R. Smith), valiuje@yahoo.com (J.M. Valiulis). 1 Present address: Colorado Cooperative Fish and Wildlife Research Unit, Patuxent Wildlife Research Center, 12100 Beech Forest Road, Laurel, MD 20708, USA. BIOLOGICAL CONSERVATION 132 (2006) 300 – 310 available at www.sciencedirect.com journal homepage: www.elsevier.com/locate/biocon