Leptodactylus vastus (LEPTODACTYLIDAE) predation on an endemic frog, and a compilation of its diet

Diet composition constitutes basic information on the natural history of the species. Despite the amount of data acquired in the last years, much remains to be known specially for geographically widespread species. Here we compiled the available dietary items of Leptodactylus vastus and report the first predation event upon Rupirana cardosoi by a juvenile L. vastus. The fact these species are syntopic in the region probably resulted in this novel predation event. Different from previous L. vastus predation observations, the specimens we observed do not present a striking difference in body size, but L. vastus was able to almost swallow L. cardosoi, coherent with findings that mouth size is related to prey selection in anurans. Also, our literature review showed that L. vastus is a generalist and opportunistic predator, that prey upon small vertebrates (Amphibia, Squamata, and Mammalia).

Morphological and Molecular Evidence Reveals the First Record of the Coral Snake Micrurus filiformis (Serpentes: Elapidae) as Prey of the Piranha Pygocentrus cariba (Teleostei: Serrasalmidae)

Coral snakes of the genus Micrurus have been recorded as prey of rapacious birds, some mammals and other snakes, but so far not as prey of fishes. The black spotted piranha, Pygocentrus cariba, is an opportunistic predator that feeds mainly on fishes, occasionally on other vertebrates, but has so far not been reported to prey on snakes. Herein, based on morphological and molecular data (mitochondrial 16S fragment), we report the first case of predation of P. cariba on the coral snake Micrurus filiformis. Additionally, we briefly discuss the significance of this new finding for the diet of P. cariba and comment on the systematics and distribution of M. filiformis.

Contribution of small mammal taphonomy to the last Neanderthal occupations at the El Salt site (Alcoi, southeastern Spain)

The El Salt site (Alcoi, Alicante, Spain) is one of the latest Neanderthal sites in the south-eastern Iberian Peninsula. The disappearance of this human group is controversial and needs detailed studies from different research areas. Taphonomy is essential to establish how representative is a fossil assemblage of the past living organisms that produced it and to interpret the formation process of the fossil site. In the case of El Salt, we have analyzed the micromammal assemblages of Units X and V, which contain fossils of Neanderthals and/or evidence of their activity. In contrast with previous identifications of the little owl (Athene noctua), our detailed taphonomic study shown here allows us to conclude that the main predator involved in the production of the micromammal assemblages was the European eagle owl (Bubo bubo). This is an opportunistic predator whose feeding preferences and behavior reflect the abundance of local micromammalian species, which can therefore provide a representation of past ecosystems near El Salt. The taphonomic information provided by this study also indicates the absence of transport and reworking processes, and reinforces previous paleoecological interpretations, suggesting an increase of aridity at the top of El Salt sequence that coincided with the local disappearance of Neanderthals.

Feeding Habits of the Non-Native Mayan Cichlid, Mayaheros urophthalmus, in Estuarine Tributaries of Southwest Florida

Foraging habits of the non—native Mayan Cichlid (Mayaheros urophthalmus) were investigated in the tidal tributaries to the Estero Bay and Wiggins Pass estuaries in southwest Florida (USA) during 2011—2013. Dietary analysis was conducted by identifying contents in the digestive tracts of 747 fish and volumetrically measuring the food items. Detritus was the predominant food item by frequency (97–100%), volume (34–48%), and alimentary importance index (47–64%). Bivalves, gastropods, decapod and cirriped crustaceans, coleopterans, serpulid polychaetes, and fish scales frequently (>50%) occurred in samples but volume and importance differed among tributaries. Results indicate that the Mayan Cichlid in southwest Florida tidal tributaries is an opportunistic predator of hard—shelled invertebrates. Although there was considerable overlap in dietary composition, percent volume of food items was significantly different among tributaries during dry seasons. In each tributary, detritus was consumed in greater percentage during the dry season and benthic invertebrates were consumed in greater percentages during the wet season. Consumption of detritus, algae, and plant material may be incidental to predation on benthic invertebrates but more information is needed on digestion and assimilation of food items. Variability in diet among the tributaries in the current study and among other studies was presumably a function of habitat characteristics and the corresponding availability of prey types.

EFFECT OF TIME DELAY IN A CANNIBALISTIC STAGE-STRUCTURED PREDATOR–PREY MODEL WITH HARVESTING OF AN ADULT PREDATOR: THE CASE OF LIONFISH

The progressive and increasing invasion of an opportunistic predator, the lionfish (Pterois volitans) has become a major threat for the delicate coral-reef ecosystem. The herbivore fish populations, in particular of Parrotfish, are taking the consequences of the lionfish invasion and then their control function on macro-algae growth is threatened. In this paper, we developed and analyzed a stage-structured mathematical model including P. volitans (lionfish), a cannibalistic predator, and a Parrotfish, its potential prey. As control upon the over predation, a rational harvest term has been considered. Further, to make the system more realistic, a delay in the growth rate of juvenile P. volitans population has been incorporated. We performed a global sensitivity analysis to identify important parameters of the system having significant correlations with the fishes. We observed that the system generates transcritical bifurcation, which takes the P. volitans-free equilibrium to the coexistence equilibrium on increasing the values of predation rate of adult P. volitans on Parrotfish. Further increase in the values of the predation rate of adult P. volitans on Parrotfish drives the system into Hopf bifurcation, which induces oscillation around the coexistence equilibrium. Moreover, the conversion efficiency due to cannibalism also has the property to alter the stability behavior of the system through Hopf bifurcation. The effect of time delay on the dynamics of the system is extensively studied and it is observed that the system develops chaotic dynamics through period-doubling oscillations for large values of time delay. However, if the system is already oscillatory, then the large values of time delay causes extinction of P. volitans from the system. To illustrate the occurrence of chaotic dynamics in the system, we drew the Poincaré map and also computed the Lyapunov exponents.

Diet of longnose stingray Hypanus guttatus (Myliobatiformes: Dasyatidae) in tropical coastal waters of Brazil

This study investigated the diet of longnose stingray Hypanus guttatus in the tropical waters of north-eastern Brazil. Samples were obtained from monthly sampling of artisanal fisheries from August 2007 to July 2008. A total of 258 specimens were examined, 127 females and 131 males, and stomach contents analysis suggested H. guttatus to be a generalist and opportunistic predator feeding on the most available prey in the environment. There was no significant difference in the diet composition of males and females, or between seasons. However, an ontogenetic dietary shift was observed with larger individuals having an increased proportion of molluscs in the diet, whilst smaller individuals predated primarily on small crustaceans.