MORPHOLOGICAL AND DEMOGRAPHIC ANALYSES OF THE BLACKCHESTED
SPINY-TAILED IGUANA, CTENOSAURA MELANOSTERNA,
ACROSS THEIR RANGE: IMPLICATIONS FOR POPULATION LEVEL
MANAGEMENT
STESHA A. PASACHNIK1,2, CHAD E.MONTGOMERY3, LESLIE E. RUYLE4,5, JEFFREY P. CORNEIL6,
AND EDOARDO E. ANTÚNEZ7

1Bay Islands Foundation, Honduras, e-mail: SAPasachnik@gmail.com
2Institute for Conservation Research, San Diego Zoo Global, Escondido, California 92027, USA
3Biology Department, Truman State University, Kirksville, Missouri 63501, USA
4Odum School of Ecology, University of Georgia, Athens, Georgia 30602, USA
5Applied Biodiversity Science Program, Texas A&M University, College Station, Texas 77843, USA
66116 Kirkwood Place N, Seattle, Washington 98103, USA
7Universidad Nacional Autonoma de Honduras, Tegucigalpa, Honduras

Abstract.—The Black-chested Spiny-tailed Iguana, Ctenosaura melanosterna, is listed as Endangered by the IUCN
Redlist Assessment and under Appendix II of CITES. The species has two evolutionarily significant units (ESUs), found
in the Valle de Aguán and the Cayos Cochinos Archipelago, Honduras. Each ESU has been shown to be genetically
distinct and each is listed, for differing reasons, as Critically Endangered by the IUCN. Habitat destruction and
overharvesting for consumption and the pet trade are among the top threats facing the mainland, Valle de Aguán,
population. The Cayos Cochinos population faces similar threats to a lesser degree; however, its restricted range (2.2
km2) heightens the potential severity of these threats, and makes this population highly susceptible to the impact of
hurricanes. We examined body size, demography, and body condition in both populations. Our results show that the
average adult size is smaller on the mainland, and there are more than expected small individuals in that population.
Additionally the sex ratio is significantly male biased on the mainland relative to the islands. These results demonstrate
evidence of a more severe poaching pressure on the mainland that is biased towards larger individuals and females. Body
condition index did not differ between the more disturbed mainland area and the more pristine island area, suggesting
that habitat alteration does not pose as serious a threat to the mainland population as poaching. Potential negative effects
of a restricted range on the morphology and demography of the island ESU were observed. Conservation measures
should acknowledge the differences between the ESUs when defining management initiatives for this species.