Abstract

GIRALDO, ALAN; GARCES-RESTREPO, MARIO F; CARR, JOHN L  and  LOAIZA, JHONATAN. Population size and structure of the large-nosed wood turtle (Rhinoclemmys nasuta, Testudines: Geoemydidae) in an insular environment of the Colombian Pacific region. Caldasia [online]. 2012, vol.34, n.1, pp.109-125. ISSN 0366-5232.

Rhinoclemmys nasuta (Boulenger 1902) is an endemic turtle listed in the Colombian red book of reptiles as an endangered species. This is a mid-sized aquatic turtle that inhabits rivers and creeks in the Tumbes-Chocó region, from the Esmeraldas River basin ( Ecuador ) to the middle region of the Atrato River basin ( Chocó, Colombia ). To date, the limited knowledge of the natural history and ecology of this species has impeded an appropriate assessment of its conservation status. Herein, we analyzed the population size and structure of R. nasuta from an insular locality in the Colombian Pacific region (Isla Palma, Bahía Málaga, Valle del Cauca). The studied population was dominated by adult individuals, with a female: male: juvenile ratio of 1.00: 0.71: 0.85. Females were significantly larger than males (♀: 179.87 ± 3.27 mm; ♂: 151.83 ± 2.41 mm) with a sexual dimorphism index of 1.18. The population size estimate based on capture-recapture records was 990 individuals (CI_90%: 941 to 1044 ind) with a mean density of 2444 ± 122 turtles per ha. Despite the strong sexual dimorphism detected, the relationship between carapace length and weight indicates isometric growth (b=3.04), with a similar growth tendency in both females and males. This is the first study on the ecology of a continental turtle species from the Pacific region of Colombia. This information on R. nasuta will be useful in the conservation initiatives for the turtles of Colombia

Keywords : Neotropical turtles; population size; population density; morphometrics; sexual dimorphism; Rhinoclemmys; larged-nosed wood turtle; Colombia.

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