A review of environmental and anthropogenic variables used to model jaguar occurrence

Jaguars (Panthera onca) are a landscape species of conservation importance and our understanding of environmental and anthropogenic drivers of jaguar occurrence is necessary to improve conservation strategies. We reviewed available literature to simply describe environmental and anthropogenic variables used and found to be significant in occurrence modeling. We reviewed 95 documents published from 1980 to 2021 that focused on jaguar occurrence and that used 39 variable types (21 anthropogenic, 18 environmental) among different techniques, scales, and approaches. In general, these variables included both anthropogenic (roads, land use, human activities, and population) and environmental (climate, vegetation, ecological interactions, topographic, water, and others) factors. Twelve variables were identified as affecting jaguar occurrence overall, eleven at local scale and seven at broad scales (regional and continental). Focusing more specifically on the variables that correlate with occurrence should help researchers to make better predictions in areas without quantitative jaguar data.

The Use of Camera Traps and Auxiliary Satellite Telemetry to Estimate Jaguar Population Density in Northwestern Costa Rica

Simple Summary

We used data from a grid of camera traps, combined with satellite telemetry data from one female jaguar, to estimate jaguar population density in northwestern Costa Rica. Our estimate of 2.6 females and 5.0 males per 100 km² was influenced by camera placement and sex of the jaguar, and indicated the importance of telemetry data to improve field design and parameter estimation. We recommend population assessments of at least 3 consecutive months, expanding the survey area to one several times the size of an individual’s home range, and including sex and camera placement considerations to reduce bias in jaguar density estimates.

Abstract

Regular evaluation of jaguar (Panthera onca) population status is an important part of conservation decision-making. Currently, camera trapping has become the standard method used to estimate jaguar abundance and demographic parameters, though evidence has shown the potential for sex ratio biases and density overestimates. In this study, we used camera trap data combined with satellite telemetry data from one female jaguar to estimate jaguar population density in the dry forest of Santa Rosa National Park in the Guanacaste Conservation Area of northwestern Costa Rica. We analyzed camera trap data collected from June 2016 to June 2017 using spatial capture-recapture methods to estimate jaguar density. In total, 19 individual jaguars were detected (11 males; 8 females) with a resulting estimated population density of 2.6 females (95% [CI] 1.7–4.0) and 5.0 male (95% [CI] 3.4–7.4) per 100 km². Based on telemetry and camera trap data, camera placement might bias individual detections by sex and thus overall density estimates. We recommend population assessments be made at several consecutive 3-month intervals, that larger areas be covered so as not to restrict surveys to one or two individual home ranges, as in our case, and to carry out long-term camera monitoring programs instead of short-term studies to better understand the local population, using auxiliary telemetry data to adjust field designs and density estimations to improve support for jaguar conservation strategies.

Osteophagia of sea turtle bones by white-tailed deer (Odocoileus virginianus) in Santa Rosa National Park, northwestern Costa Rica

Herbivores obtain nutrients mostly from the vegetation they consume, but may obtain additional minerals during periods of nutritional stress by consuming bones (osteophagia), a behavioral strategy that has been reported for many wild ungulate species, including the white-tailed deer (Odocoileus virginianus). Here we document multiple records (n = 183 camera-trap records) of osteophagia by white-tailed deer chewing sea turtle remains (resulting from jaguar [Panthera onca] predation) near a nesting beach in Santa Rosa National Park, Costa Rica during January-September 2017. Females with fawns, males with hard and velvet-covered antlers, and non-spotted fawns reached a peak of sea turtle bone consumption during June to August. We hypothesize that seasonality, sex, age, and individual growth stage influence the frequency of osteophagy as a strategy to cope with environmental changes and food resource scarcity. Finally, these observations highlight the role of an apex predator as indirectly influencing rare but important ecological processes.

Environmental and anthropogenic factors synergistically affect space use of jaguars

Large terrestrial carnivores have undergone some of the largest population declines and range reductions of any species, which is of concern as they can have large effects on ecosystem dynamics and function.^1-4 The jaguar (Panthera onca) is the apex predator throughout the majority of the Neotropics; however, its distribution has been reduced by >50% and it survives in increasingly isolated populations.⁵ Consequently, the range-wide management of the jaguar depends upon maintaining core populations connected through multi-national, transboundary cooperation, which requires understanding the movement ecology and space use of jaguars throughout their range.^6-8 Using GPS telemetry data for 111 jaguars from 13 ecoregions within the four biomes that constitute the majority of jaguar habitat, we examined the landscape-level environmental and anthropogenic factors related to jaguar home range size and movement parameters. Home range size decreased with increasing net productivity and forest cover and increased with increasing road density. Speed decreased with increasing forest cover with no sexual differences, while males had more directional movements, but tortuosity in movements was not related to any landscape factors. We demonstrated a synergistic relationship between landscape-scale environmental and anthropogenic factors and jaguars' spatial needs, which has applications to the conservation strategy for the species throughout the Neotropics. Using large-scale collaboration, we overcame limitations from small sample sizes typical in large carnivore research to provide a mechanism to evaluate habitat quality for jaguars and an inferential modeling framework adaptable to the conservation of other large terrestrial carnivores.

Reproduction of white-tailed deer in a seasonally dry tropical forest of Costa Rica: a test of aseasonality

The reproductive season of white-tailed deer (Odocoileus virginianus) has been hypothesized to be aseasonal south of about 14°–18°N latitude, where annual variation in day length is low. We tested this idea by using camera-trap data (1,336 photographed individuals identified by age and sex) collected during 2011–2017 in the dry tropical forest of Santa Rosa National Park, northwest Costa Rica, where wet and dry seasons are well-defined. We identified variation in monthly occurrence of spotted deer fawns, as well as the status of antler growth of male deer, specifically related to the very seasonal environment of the region. Year-round reproduction likely occurs, but the rainfall pattern in the area greatly influences the relative frequency of reproductive indicators, with most births occurring during the dry season, and a second peak occurring toward the latter part of the wet season. We speculate that food resources are the major influence on reproductive patterns, and that variation in types and timing of food resource availability likely account for the variation in reproductive patterns.