Reptiles as principal prey? Adaptations for durophagy and prey selection by jaguar (Panthera onca)

Abstract

We examined the evidence supporting the hypothesis that jaguars (Panthera onca) have morphological and behavioural adaptations to facilitate reptile predation. Jaguars' head and bite features show adaptations to durophagy (consumption of hard-integumented prey) that are very unusual within the genus Panthera. These include: thick canines, well-developed head muscles and a fatal bite directed to braincase or nape. These characteristics have been previously considered an adaptation for the consumption of reptilian prey, whose thick integument poses a challenge to predation. Although causation of any trait as result of natural selection is hard to demonstrate with ecological evidence, its consequences can be suggested and predictions made. Here, through a review of the literature on jaguar predatory habits, we tallied the evidence for saurophagy against environmental characteristics correlated with jaguar predation on reptiles. We offer a new explanation for the presence of those traits, based on the selection patterns, prey abundances and main predation habits over the geographic range of the jaguar. We believe that these features allow jaguars to overcome dangerous and/or armoured prey by dispatching them rapidly through a bite to the head or nape. Reptile consumption is restricted to areas of high reptile abundance while dangerous or armoured prey is consistently preyed upon throughout the jaguar's distribution, and selected even when their abundance is low. This questions the validity of the saurophagy hypothesis. We believe that these results are relevant to jaguar conservation and management, because some of the main prey species are severely threatened over their range, and because threatened reptiles are also consumed as prey. ARTICLE HISTORY

First records of Brazilian three-banded armadillo (Tolypeutes tricinctus, Mammalia, Cingulata, Chlamyphoridae) predation by jaguar (Panthera onca, Mammalia, Carnivora, Felidae)

“…These features are considered adaptations to prey on larger animals (Hayward et al, 2016), but also to attack by biting hard tissues, such as by braincase piercing or by cracking open the shells of tortoises (Meachen-Samuels & van Valkenburgh, 2009). Hence, they allow P. onca to prey on species that rely on armor as a defense mechanism (Miranda et al, 2016), which is the case of chelonians (Brito et al, 2018) and Tolypeutes spp. Consequently, P. onca is the most probable predator that could use a bite on the hard carapace of these armadillos to feed on them.…”

Warped finite element models predict whole shell failure in turtle shells

“…,; Miranda et al. ), and even the same predator species may attempt multiple strategies to fracture the shell (Emmons, ). This unpredictability may impose selection for relative uniformity of shape and microstructure across the turtle shell, leading to a relatively homogeneous structure with homogeneous mechanical properties, suitable for modeling.…”

“…Besides its relative simplicity, it is also noteworthy that the shell has likely evolved in response to selective pressure for withstanding very unpredictable stresses. Predators can attack turtles in many ways (Emmons, 1989;Acosta et al 2004;Medica & Greger, 2009;Salera et al 2009a,b;Miranda et al 2016), and even the same predator species may attempt multiple strategies to fracture the shell (Emmons, 1989). This unpredictability may impose selection for relative uniformity of shape and microstructure across the turtle shell, leading to a relatively homogeneous structure with homogeneous mechanical properties, suitable for modeling.…”

High moon brightness and low ambient temperatures affect sloth predation by harpy eagles

“…owls), of improving acoustic detection of prey. Combined with extremely acute vision, which is likely associated with a high density of photoreceptor cells in the retina typical of many diurnal raptors (Lisney et al, 2013), harpy eagles are superbly capable of locating inconspicuous prey, enabling them to be the only Neotropical apex predator to specialise on the highly secretive sloths (Miranda, 2015;Miranda, Menezes & Rheingantz, 2016). Harpy eagle activity patterns can be investigated with further research using either intensive telemetry-assisted follows or camera trapped nests.…”