Density and population structure of the jaguar (Panthera onca) in a protected area of Los Llanos, Venezuela, from 1\xa0year of camera trap monitoring

Włodzimierz Jędrzejewski,José F Romero,Ángel L Viloria,Margarita Lampo,Hugh S Robinson,Maria F Puerto,Joshua F Goldberg,Alejandro Biganzoli,Gertrudis Gamarra,Krzysztof Schmidt,Ernesto O Boede,Grisel Velásquez,Mark Hebblewhite,Izabela Stachowicz,Luis E Calderón,Rafael Carreño,María Abarca

doi:10.1007/s13364-016-0300-2

Abstract

Density is crucial for understanding large carnivore ecology and conservation, but estimating it has proven methodologically difficult. We conducted 1 year of camera trapping to estimate jaguar (Panthera onca) density and population structure in the Los Llanos region of Venezuela on the Hato Piñero ranch, where hunting is prohibited and livestock are excluded from half of ranch lands. We identified 42 different jaguars and determined their sex, age class, and reproductive status. We estimated adult jaguar densities with spatial capture-recapture models, using sex/reproductive state and session as covariates. Models without temporal variation received more support than models that allowed variation between sessions. Males, reproductive females, and nonreproductive females differed in their density, baseline detectability, and movement. The best estimate of total adult jaguar population density was 4.44 individuals/100 km2. Based on reproductive female density and mean number of offspring per female, we estimated cub density at 3.23 individuals/100 km2 and an overall density of 7.67 jaguars/100 km2. Estimated jaguar population structure was 21% males, 11% nonreproductive females, 26% reproductive females, and 42% cubs. We conclude that extending the sampling period to 1 year increases the detectability of females and cubs and makes density estimates more robust as compared to the more common short studies. Our results demonstrate that the Venezuelan Llanos represent important jaguar habitat, and further, they emphasize the importance of protected areas and hunting restrictions for carnivore conservation.

Highlights

Population density is central to understanding the ecology, spatial distribution, and abundance of all organisms (Krebs 2001), yet estimating density reliably remains a challenging problem in applied ecology
Our study demonstrates that protected areas in Los Llanos are potentially important jaguar habitat and that jaguar populations in this region may reach some of the highest densities recorded for South America
Hato Piñero is an unquestionable jaguar hotspot in northern South America, it needs more international concern to maintain its good state of conservation, especially in the context of the political instability, growing environmental risks, and uncertain future of this region

Summary

Introduction

Population density is central to understanding the ecology, spatial distribution, and abundance of all organisms (Krebs 2001), yet estimating density reliably remains a challenging problem in applied ecology. This issue remains especially persistent for ecologically important large carnivores. Accurate density estimates are critical to evaluate population size and trends of large carnivores, an increasingly important aim given worldwide declines of many of these species (Gros et al 1996; Treves and Karanth 2003; Ripple et al 2014). Integrating methods to estimate large carnivore population breeding structure with density could improve population trend predictions and promote effective conservation (Woodroffe 2011; Rosenblatt et al 2014)

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