Predation is acknowledged as one of the main forces of natural selection. It is involved in the regulation of a diverse range of evolutionary and ecological processes, including Cambrian diversity explosion (Bengtson 2002), top-down population regulation (Orihuela et al. 2014), landscape-level soil nutrient distribution (Bump et al. 2009), habitat use of a variety of prey species (Preisser et al. 2005), and natural selection itself (Genovart et al. 2010). Being such a strong selective force, predation has been responsible for a variety of adaptations in prey species. A large and continually growing body of research has focused on this subject (Greene 1988; Caro 2005), and a general classification of antipredator defenses separates prey strategies into 2 main classes (Brodie et al. 1991): predation avoidance by flight, being constantly vigilant and morphologically adapted to escape via speed (passerines, most monkeys, iguanids), and prey that is able to confront (peccaries, boars, skunks) or physically resist predators (armadillos, tortoises).

Among the most remarkable adaptations of physical resistance to predation are the shells developed by chelonians. Formed by the fusion of vertebras, ribs, and sternal bones, this unique development has been the basis of the group's evolutionary success. Living chelonians can be found in nearly every major ecosystem on Earth, except those of the polar regions (Ernst and Barbour 1989). The shell is often complemented by spiny scutes on the legs and has the ability to house the retracted legs and head. Predators have developed a variety of strategies to overcome this suite of defensive measures, including member amputation (Heithaus et al. 2008), dropping animals from the air or cliffs (Watson 2010), and direct shell destruction (Salera-Junior et al. 2009). Despite this, adults of most chelonian species suffer low mortality (Iverson 1991). However, Panthera onca (jaguar) is well known for preying on chelonia (Da Silveira et al. 2010). Their heads show several characteristics relating to durophagy, including thick canines and large masseter and temporal muscles (Seymour 1989) and one of the strongest bites relative to body size in the genus Panthera (Christiansen and Adolfssen 2005).

Here we review chelonian species preyed on by jaguars in order to provide to other researchers authors with a current, single-source review of chelonian predation by jaguars. We also synthesize information on body size and reproductive condition of chelonia that are preyed on by jaguars. In addition, we report the first record of predation on Acanthochelys macrocephala by jaguar.

A search of the literature concerning interactions between jaguars and turtles was performed using Google Scholar. We used the key words jaguar, P. onca, and onça-pintada combined with diet, feeding habits, food habits, hábitos alimentarios, and dieta. This allowed us to find published and unpublished information in English, Portuguese, and Spanish.

In September 2014, we found a dead adult individual of A. macrocephala on the Transpantaneira Park Road (lat 17°16′47″S, long 56°52′16″W, WGS84), located within the Brazilian Pantanal wetlands of the Paraguay River basin. Acanthochelys macrocephala is a medium-sized freshwater turtle that lives in marshes, wetland areas, shallow bays, and brackish lagoons (Rhodin et al. 2009). The individual was found on dry land, with visible bite marks on the carapace, and jaguar tracks were found at the site. The distance between canines (> 70 mm) marked on the carapace was consistent with that of a jaguar bite (Hoogesteijn and Hoogesteijn 2005), confirming the predator's identity.

In addition, our search revealed records of jaguar predation on 15 species of chelonia, totaling 16 with the addition of A. macrocephala (Table 1). Of these, 3 species were terrestrial, 8 freshwater, and 5 marine. The latter were killed during nesting times, as were the large freshwater species, which usually nest in large numbers on beaches. Small chelonia, such as A. macrocephala, can be considered a rare prey of jaguars because this turtle occasionally moves onto dry land to migrate to other water bodies, as these bodies of water are not always connected (Junk et al. 2011). This kind of terrestrial movement is common in small and midsized freshwater turtles living in seasonal environments (Bodie and Semlitsch 2000).

Table 1. Chelonian species preyed on by the jaguar, including the average mass of each species. An “X” indicates that the predation event occurred during nesting.

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Chelonia predation by jaguars has been recorded since the early days of Neotropical natural history (e.g., Humboldt 1877). Topic of durophagy, however, is the subject of little research (Miranda et al. 2016). Here we have shown that the jaguar preys on chelonians, including such heavily armored species as the Chelonoidis tortoises, and also small species. The study also extends knowledge of such predation to marine turtles, which are extensively preyed on during the nesting time. Predation events are usually higher during peak nesting season and increase as nesting populations increase (Arroyo-Arce and Salom-Pérez 2015). Predation of nesting marine turtle has been the subject of intense discussion because of the conservation concern for the species being preyed on (especially as they are all reproductive females) (Veríssimo et al. 2012; Arroyo-Arce and Salom-Pérez 2015). This behavior is unique in large Panthera cats, with no other species known to prey on chelonia to such an extent.

Although chelonians have evolved formidable morphological adaptations to avoid predation, the jaguar's mandibular adaptions for durophagy appear to have surpassed them. Jaguars possess the potential capacity to kill adults of virtually all chelonian species within their distribution, and our data indicate that they prey on at least 16 species, including A. macrocephala. They can take advantage of mass nesting events to transform large aquatic chelonians into staple food items as well as of opportunistic predation. Predation on nesting females can lead to conservation conflicts when the prey species is considered threatened. We suggest that further research on jaguars preying on chelonia approach the subject from the foraging theory point of view (Stephens et al. 2007), comparing predation with prey abundance.