For people living on the Brazilian plains jaguars versus cattle is an age-old conflict. South America’s Pantanal region is important to the continued survival of jaguars, but it also has been home to cattle ranching for more than 200 years.
New insights into this conflict are offered through a study using global positioning system (GPS) technology to track the predatory patterns of these jaguars, recording what animals they kill and how often.
The study appears in the June 2010 issue of the Journal of Mammalogy. Previous studies depended on scat analyses, direct observations of prey killed, and discovery of prey remains to document kills.
The present study went farther, following the animals’ movements to document kill rates and predation patterns of jaguars over several years.
Ten jaguars were equipped with GPS collars and monitored from October 2001 to April 2004. By tracking the cats, researchers collected 11,787 GPS locations and identified 1,105 clusters of concentrated use, such as kill sites, dens, or bed sites. The investigators visited these clusters to learn more about the jaguars’ activities.
Prey remains were identified at more than 400 kill sites. Jaguars most often killed native species; 68% of the carcasses found included caiman (a crocodilian reptile), piglike peccaries, feral hogs, marsh deer, and giant anteaters. 32% were cattle.
During the four years of the study, jaguars increasingly killed peccaries and decreased their predation on cattle. The patterns revealed by the study show that seasonal rainfall and subsequent water levels on the Pantanal influenced the type of prey jaguars killed.
As water levels increased, caiman became more prevalent, and jaguars preyed on them more frequently. When water levels fell, not only did caiman become scarcer, but ranchers also moved cattle out into pastures, making them a readily available food source for the cats.
Researchers suggest that authorities and ranchers accept the coexistence of jaguars and cattle. A large number of cattle present may actually help support the continued survival of jaguars.
Ranchers should recognize that loss of livestock is inevitable and take part in compensation programs. Conversely, compensation for ranchers might be associated more positively with threats to their livestock, with payments conditional on jaguar abundance in an area.
Full text of the article, “Kill Rates and Predation Patterns of Jaguars (Panthera onça) in the Southern Pantanal, Brazil,” Journal of Mammalogy, Volume 91, Issue 3, June 2010, is available at http://www2.allenpress.com/pdf/mamm-91-03-722-736.pdf