The feral pig as prey for jaguars: A reply to the ‘Letter from the Conservation Front Line’ by Verdade et al.

Abstract

Due to habitat loss, poaching and high hunting pressure on their prey, the jaguar Panthera onca is one of the most endangered top predators in the Americas (Galetti et al., 2013; Treves & Bruskotter, 2014). The population of jaguars in the Brazilian Atlantic Forest was estimated to be less than 250 mature individuals, split into many isolated populations (Haag et al., 2010; Beisiegel, Sana & Moraes, 2012). In addition, most of its prey, white-lipped peccaries Tayassu pecari and tapirs Tapirus terrestris, are extinct or restricted to only a few areas (Jorge et al., 2013). In their ‘Letter from the Conservation Front Line’ published in Animal Conservation, Verdade et al. (2015) suggested that feral pigs (Sus scrofa) (Pedrosa et al., 2015), could be an alternative prey for jaguars and may help their populations to recover in Atlantic forest. Although jaguars are known to prey on feral pigs in Pantanal (Cavalcanti & Gese, 2010), we are skeptical that the jaguar's population size would increase and the distribution expand based upon preying on the pigs, and we doubt that jaguars will control the invasion of feral pigs in Brazil. First, feral pigs in the Pantanal are much smaller (body mass ~40 kg, Desbiez et al., 2009) than in the Atlantic forest (body mass ~100 kg, Oliveira, 2012), where they are therefore less likely to be preyed upon by jaguars, unless jaguars selectively prey upon juveniles and piglets. Second, prey's behavior is as important as their body size in determining the predator's success (Hopcraft, Sinclair & Packker, 2005); feral pigs are more aggressive (Graves, 1984) than native species or cattle (Montenegro, 1998; Cavalcanti et al., 2010; Cavalcanti & Gese, 2010). Third, although prey availability is one of the main issues for recovering top predator populations (Galetti et al., 2013; Ripple et al., 2014), jaguars are seen as a significant threat to cattle ranching (Ripple et al., 2014; Tortato et al., 2015). Currently, there are 10 million head of cattle in São Paulo state (Bueno, Martins & Caser, 2015) and they are probably a more logical choice for jaguars (Cavalcanti et al., 2010; Cavalcanti & Gese, 2010). Although cattle are bigger than feral pigs, they are constrained within fenced fields and are less aggressive due to domestication (Cavalcanti et al., 2010). Therefore, any increase in the population of jaguars is likely to negatively impact the attitude of farmers to this predator. We believe that the most effective means of garnering support for controlling invasive feral pigs is to demonstrate their socioeconomic impacts (Jeschke et al., 2014; Massei et al., 2015). Increasing human hunting pressure on feral pigs may decrease hunting pressure on jaguar's prey (Desbiez et al., 2011), thus indirectly benefiting jaguars.