Abstract
Knowledge on long-term population trends in crocodilians is essential to assess the effectiveness of conservation areas and to guide sustainable management practices. We studied changes in population size of spectacled (Caiman crocodilus) and black caimans (Melanosuchus Niger) over a period of 17 yr at Mateococha, a black-water lake located in Cuyabeno Wildlife Reserve, western Amazonia, Ecuador. Using standardized spotlight counts and two mark-recapture surveys, we estimated the population abundance, body size structure, and sex ratio in 1994, 2004, and 2011. The maximum number of C. crocodilus recorded in 1994 (147 individuals; 33 individuals/kilometer [ind/km] of lakeshore) declined by 2004 to 94 individuals (21.1 ind/km) and by 2011 to 63 individuals (14.2 ind/km). The number of M. Niger recorded was low but constant (5-7 individuals; 1.1-1.6 ind/km) throughout the study, suggesting that factors causing the decline in C. crocodilus were not related to the M. Niger population trend. Large C. crocodilus adults (total length 150-220 cm) were frequent in 1994 but became rare in 2004 and 2011. The sex ratio of captured C. crocodilus was male-biased during all periods. The causes of the population decline are unknown, but available evidence suggests that illegal hunting and habitat degradation are likely culprits despite the protected status of the Cuyabeno Reserve. Our findings question the effectiveness of protected areas to ensure long-term survival of caiman populations in Ecuador.
| Original language | English |
|---|---|
| Pages (from-to) | 31-38 |
| Number of pages | 8 |
| Journal | Journal of Herpetology |
| Volume | 54 |
| Issue number | 1 |
| DOIs | |
| State | Published - 2020 |
Bibliographical note
Publisher Copyright:© Copyright 2020 Society for the Study of Amphibians and Reptiles.
Funding
This study was funded in 1992–1994 by the Odum Foundation, Cuyabeno Foundation, the Institute of Ecology of the University of Georgia, and the National Oceanic and Atmospheric Administration (NOAA) through a grant led by P. Colinvaux, E. Asanza, and M. Bush; in 2004–2006 by Unity and Cooperation for Development of Peoples (UCODEP) and Rufford Small Grants; and in 2011 by Pontificia Universidad Católica del Ecuador (PUCE), Idea Wild, and the Crocodile Specialist Group through a Student Research Assistant Scheme (SRAS) grant. Research permits were issued by Ministerio del Ambiente of Ecuador (No. O07-IC-FAU/-DPS/MA), and PUCE and L. Hernández (Neotropic Turis) provided logistic support in Laguna Grande of Cuyabeno. We thank E. Asanza for pioneering studies on caimans in Cuyabeno Reserve and for providing field training to SRR. R. Da Silveira, R. Botero, and Mamirauá Sustainable Development Institute provided research training to DAO. W. Magnusson and R. Da Silveira provided comments on early versions of the manuscript. E. Tynan reviewed grammar and style. A. Vallejo and C. Ortiz deserve special recognition for field assistance in 1994 and 2011, respectively.
| Funders |
|---|
| National Oceanic and Atmospheric Administration |
| University of Georgia |
