Population status of the American crocodile, Crocodylus acutus (Reptilia: Crocodylidae) and the spectacled caiman, Caiman crocodilus (Reptilia: Alligatoridae) in the Costa Rican North Caribbean
Along the Costa Rican Caribbean shoreline, it is possible to find two species of crocodilians, the American crocodile (Crocodylus acutus) and the spectacled caiman (Caiman crocodilus). This region can be divided geographically into three subregions: North, Central, and South Caribbean. We conduct...
Autores Principales: | Sandoval Hernández, Iván, Sánchez Ramírez, Juan José de Los Ángeles, Bolaños Montero, Juan Rafael, Monrós González, Juan Salvador |
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Formato: | Artículo |
Idioma: | Inglés |
Publicado: |
Istituto di Ricerca sugli Ecosistemi Terrestri (Italia)
2024
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Materias: | |
Acceso en línea: |
http://hdl.handle.net/11056/27262 https://doi.org/10.4081/tz.2021.77 |
Sumario: |
Along the Costa Rican Caribbean shoreline, it is possible to find two species
of crocodilians, the American crocodile (Crocodylus acutus) and the spectacled caiman
(Caiman crocodilus). This region can be divided geographically into three subregions:
North, Central, and South Caribbean. We conducted this research in the North Caribbean,
between October 6, 2018 and August 31, 2019. Specifically, we worked in the area lying
between the Jalova Station of the Tortugero National Park (TNP) and Agua Dulce Lake
situated in the northern tip of Machuca Island, at the mouth of the Colorado River inside
the Barra del Colorado National Wildlife Refuge (BACORE), which includes other
connecting wetlands as well (Sierpe River, Samay Lake). Overall, this study area had
an approximate extension of 408 km2 characterized by large, wide and deep canals, as
well as wetlands, meanders, and adjacent lakes. The sampling was performed along 10
segments that varied in length from 7.5 km up to 29.49 km, located in the nearby zones
of TNP and BACORE. In these zones, nightly counts were carried out using dazzling
lamps. Individuals of C. acutus and C. crocodilus were classified into eight and six body
size classes, respectively (both with 50 cm intervals). A relative abundance of 0.55
crocodiles and 1.37 caimans per linear kilometer was estimated during these spotlight
surveys. The capture of 39 caimans let us to estimate a ratio of 30 males to 9 females
(3.3:1 M:F). In stark contrast, only 1 male and 1 female crocodile were captured. A total
of 85 C. acutus and 205 C. crocodilus were observed. Regarding the number of caiman
sightings in the TNP, a statistically significant difference was found (Χ2=5.62, p≤0.05)
for the distribution by sizes between the zones of BACORE and TNP, whereas no such
difference was found for C. crocodilus sightings (Z=–1.22, p≥0.222). Some segments
had a higher probability of caiman occurrence than did others in the surveys performed
during the monitoring period (X2=8.36, p≤0.05), especially the Jalova-Sierpe River,
Caño Negro-Tortuguero, and Tortuguero-Samay Lake (Tortuguero subarea) segments.
Ninety percent of the sightings occurred in the BACORE zone, and this was significantly different (Χ2=7.34, p≤0.026) from the studied subareas. The number of crocodile
sightings in the Colorado River segment was significantly different and higher than the
other segments (X2=7.28, p≤0.05). There was a significant statistical difference among
the sizes in all areas of study (X2=5.529, p≤0.026). The abundance of C. acutus and C.
crocodilus in the north Caribbean part is lower than in the central Caribbean part of
Costa Rica, where this species could use the resources available in more urbanized areas. |
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