IUCN / SSC Cat Specialist Group - Digital Cat Library |
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| Sollmann, R.; Furtado, M.M.; Gardner, B.; Hofer, H.; Jacomo, A.T.A.; Torres, N.M.; Silveira, L. | |
| Improving density estimates for elusive carnivores: Accounting for sex-specificdetection and movements using spatial capture-recapture models for jaguars in central Brazil | |
| 2011 Biological Conservation (144): 1017-1024 | |
Owing to habitat conversion and conflict with humans, many carnivores are of conservation concern.Because of their elusive nature, camera trapping is a standard tool for studying carnivores. In many vertebrates,sex-specific differences in movements - and therefore detection by cameras - are likely. Weused camera trapping data and spatially explicit sex-specific capture-recapture models to estimate jaguardensity in Emas National Park in the central Brazilian Cerrado grassland, an ecological hotspot ofinternational importance. Our spatially explicit model considered differences in movements and trapencounter rate between genders and the location of camera traps (on/off road). We compared resultswith estimates from a sex-specific non-spatial capture-recapture model. The spatial model estimateda density of 0.29 jaguars 100 km_2 and showed that males moved larger distances and had higher trapencounter rates than females. Encounter rates with off-road traps were one tenth of those for on-roadtraps. In the non-spatial model, males had a higher capture probability than females; density was estimatedat 0.62 individuals 100 km_2. The non-spatial model likely overestimated density because it didnot adequately account for animal movements. The spatial model probably underestimated densitybecause it assumed a uniform distribution of jaguars within and outside the reserve. Overall, the spatialmodel is preferable because it explicitly considers animal movements and allows incorporating site-specificand individual covariates. With both methods, jaguar density was lower than reported from mostother study sites. For rare species such as grassland jaguars, spatially explicit capture-recapture modelspresent an important advance for informed conservation planning. |
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