The crab-eating raccoon (Procyon cancrivorus) is a medium-sized nocturnal carnivore widely distributed in the Neotropics, from Costa Rica to Uruguay. It inhabits forested and open areas, generally associated with limnic systems (^{González et al., 2010}). Due to its nocturnal and inconspicuous behavior, the crab-eating raccoon is considered one of the less-studied Neotropical carnivores. The species is opportunistic, and its omnivorous diet (^{Paglia et al., 2012}) includes fruits and invertebrates as well as small mammals and lizards (e.g., ^{Gatti et al., 2006}; ^{Quintela et al., 2014}; ^{Dias and Bocchiglieri, 2015}). In this paper, we investigate the diet of P. cancrivorus and report a predation event by P. cancrivorus upon a paradoxal frog (Pseudisplatensis) in the Southern Pantanal.

We searched for studies in the Web of Science (<https://webofknowledge.com/>) and Scopus (<https://www.scopus.com>) databases, using the keywords 'Procyon cancrivorus' AND 'Diet*' OR 'feed*' OR 'trophic ecology* up to 2019. Besides, we gather all data from direct searches of references in Google Scholar (https://scholar.google.com.br/). Among these compiled references, we selected only studies presenting absolute data on the diet of P. cancrivorus.

We compiled a total of 14 papers published from 1986 to 2019, with eight publications characterizing the diet of P. cancrivorus. Seven studies were performed in Brazil, distributed in Northeast, Southeast, and South, and only one study was performed in Venezuela with multiples localities. These studies accessed P. cancrivorus diet, analyzing fecal samples and stomach content. According to these studies, the diet incorporates 96 animal taxa and 35 vegetal taxa (Supplementary material. Aratus sp. (Brachyura: Decapoda) and Syagrus romanzoffiana (Arecaceae) were reported to be the animal and plant most abundant in the diet of P. cancrivorus. Coleoptera and Orthoptera were the items most frequent among six of the eight studies compiled.

Besides this information from existing literature, were here report a direct observation on P. cancrivorus foraging in a freshwater lake at Fazenda Barranco Alto Lodge in the Southern Pantanal, municipality of Aquidauana, Mato Grosso do Sul (19°34'S, 56°8' W, 114 m.a.s.l). The observation occurred by chance during fieldwork on 4 Jun 2011 from 07:10 am to 07:19 am. An adult P. cancrivorus was observed while it was catching anurans in a lagoon. The species was foraging among aquatic macrophytes, moving its hands quickly back and forth to feel possible catch underneath the water plants. It was hunting exclusively haptic and did not try to move the plants to the side to visualize possible prey in the water. In this manner, the raccoon captured and ate six anurans during nine minutes of observation. Only one of these anurans preyed by P. cancrivorus could be identified as the paradoxal frog (Pseudis platensis) (Fig. 1), an aquatic diurnal/nocturnal hylid that occurs in permanent and semi-permanent ponds (^{Dixon et al., 1995}). Paradoxal frog could be identified by its medium size (greater than Lysapsus limmelum, another aquatic hylid) and by the coloration of its thigh, with thick dark lines (^{Garda et al., 2010}) (Fig.1c). This is the first visual record of P. cancrivorus feeding upon an anuran and the first report of predation upon P. platensis by a mammal.

Figure 1 (a-c) An adult crab-eating racoon (Procyon cancrivorus) searching and preying an adult paradoxal frog (Pseudis platensis) in a lagoon in Pantanal, Mato Grosso do Sul, Brazil. (Photos: Lydia Möcklinghoff) 

Despite the wide distribution of P. cancrivorus, dietary studies were concentrated in Brazil, mainly in Protected Areas (e.g., Santos and Hartz, 1999; Gatti et al., 2016). The elevate abundance of Aratus sp. (n = 114) can be related to the mangrove environment where this species is common (^{Novaes, 2002}). Syagrus romanzoffiana is a common palm in a semideciduous forest in South Brazil and frequently is reported in dietary studies of mammals like squirrels, tapirs, peccary, brown-nosed coatis and maned wolfs (e.g., ^{Bueno and Motta-Junior, 2004}; ^{Keuroghlian and Eaton, 2008}; ^{Giombini et al., 2009}). Fruits are produced throughout the year, showing ovoid shape (ca. 2.5 cm diameter), with a soft exocarp and woody endocarp (^{Galetti et al., 1992}). The elevated frequency of Coleoptera and Orthoptera in P. cancrivorus diet is related to wide distribution and the great abundance of these orders in the environment, which facilitate their visualization and capture (^{Rafael et al., 2012}).

Earlier studies on P. cancrivorus diet show an elevated number of aquatic preys (e.g., Aratus sp.), confirming that this species forages next to water (^{Trolle, 2003}). In these analyses, on the diet of P. cancrivorus, anurans were identified only to the family level, with Bufonidae, Hylidae, and Leptodactylidae being cited. Thus, our record of P. cancrivorus preying on P. platensis was the first one to analyze the preyed anuran to species level.

Paradoxal frog has diurnal and nocturnal habits, vocalizing on the water surface, among macrophytes (^{Dixon et al., 1995}). Information on P. platensis natural history is scarce, with the majority being related to the diet of its giant tadpoles and on parasites (e.g., ^{Emerson, 1988}; ^{Arias et al., 2002}; Campião et al., 2010; ^{Ceron et al., 2017}; ^{Landgref Filho et al., 2019}). Reports of animals preying on adults of P. platensis include five bird species, another frog species, snakes, fishes, and caimans (^{Landgref-Filho et al., 2019}). Until now it was not known that also mammals hunt for this frog species. Our observation shows that the ability of the crab-eating raccoon to catch frogs in the water without visual reference, as recorded here, is possible due to the well-developed tactile abilities, using their forepaws skilfully, and other sensory skills of the species (^{Nowak and Walker, 1999}). This tactile way of hunting might be especially of interest when hunting in the dark as P. cancrivorus is known to be mainly nocturnal, such as its congeners Procyon lotor (^{Greenwood, 1982}). However, the observations here presented of diurnal foraging activity of P. cancrivorus are rare, also shows that the animal hunts in a tactile and not visual way during daytime and that this hunting strategy enables the animal to hunt in water with limited visibility and catch the frogs under the floating vegetation.

Few studies have reported diurnal habits to P. cancrivorus (^{Brooks, 1993}; ^{Carrillo and Vaughan, 1993}; ^{Gómez et al., 2005}). For the Pantanal, this is even the first evidence of a crab-eating raccoon being active during the daytime. Several factors may affect on activity times of raccoons, such as the hunting success in the previous night and individual fitness (^{Gehrt and Fritzell, 1998}). Due to the difficulty to observe predatory events in nature, these records are an important source, as they directly contribute to the knowledge of a species' natural history. Our observation reinforces the known generalist and opportunistic diet of P. cancrivorus, gives new insides about the hunting strategy of this mammal species, and it is the first record of predation on P. platensis by a mammal.