INTRODUCTION: Sight-resight studies are performed to estimate population sizes, in this case dog populations in rabies endemic areas. AIM: This study compares one- and two-day sight-resight methods with two-day as the standard to explore the feasibility and accuracy of the one-day method in different vaccination campaign strategies and dog population characteristics. METHODS: 2015 household survey data and sight-resight data are analyzed to find the percentage of free roaming and confined dogs in the community and use those to adjust the population estimate formulas. 2016 sight-resight data are analyzed as a two-day campaign and as if it had been a one-day campaign. In a sensitivity analysis, confidence intervals are explored in relation to vaccination coverage. RESULTS: Before missed mark and proportion free-roaming corrections, the one-day method results in slightly underestimated population estimates to the two-day method when the vaccination campaign is central point, overestimated when door-to-door, and far underestimated when capture, vaccinate, release. After corrections door-to-door estimates were accurate whereas central point and capture, vaccinate, release estimates substantially underestimated population sizes. DISCUSSION: Results suggest that the one-day mark-resight method could be used to conserve resources depending on the vaccination method and estimated coverage.

The black caiman (Melanosuchus niger) and the yacare caiman (Caiman yacare) have in the past been exposed to overexploitation due to the economic profit for their hides, and therefore suffered from great declines in population sizes, especially black caimans. Legal regulation efforts made it possible for these two species to recover and today they are widely distributed in South America. Evaluation of protection and management of populations of top predators like these caimans depend on the ability to detect the animals. The probability of detecting a crocodile, or any animal, is affected by several factors such as habitat complexity and behaviour why it is of importance to acknowledge such matter in order to obtain reliable results for further implications. This study aims to investigate the detection probability and abundances in these two species as a contribution to the monitoring efforts at a local scale. Night counts were performed in Cedral lagoon located in the Beni region in Bolivia. By using the relation between marked animals and resightings of them, as well as the abundance estimate produced by the Lincoln-Petersen estimator, estimates of detection probabilities could be accounted for the total caiman population (black plus yacare caimans) and the black caiman population. Very low sighting probabilities (p = 0.03) were obtained when based on marked animals who tend to be more wary after a capture event. Those based on the L-P output were higher (total caiman population p = 0.15, black caimans p = 0.15). Population sizes were estimated to 25 ± 8.5 black caimans and 34 ± 12 caimans in total. The population size based on marked animals was 12 ± 25.4 caimans.