Keyword: nicho trófico

Eating like a girl: sex differences in the diet of the lesser grison (Galictis cuja) in southern Brazil

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The lesser grison is a hypercarnivore mustelid that is widespread in South America, inhabiting a large variety of habitats, including steppes, deserts, grasslands, forests, and swamps. However, there are few scientific data on the ecology of the species. In our study, we investigate the feeding habits of the Galictis cuja in the Brazilian Pampas by analyzing the stomach contents of road-killed individuals collected from 2013 to 2023. We identify a high consumption of mammals found in 80% of the samples, comprising 75% of the prey  consumed. Amphibians, reptiles, and birds are consumed in smaller proportions. Regarding mammals, only rodents were consumed, among which Cavia sp., Holochilus brasiliensis, and Rattus sp. stand out, corresponding to 62% of biomass intake. Although there was no sexual difference in the prey consumed, we found a difference in predation rate, with males consuming more Rattus and females consuming more Cavia. As a result, males are consuming prey that is proportionally smaller (equivalent to 1/6 of their own weight) than that of females (1/3 of their own weight). This is contrary to what is expected due to the sexual dimorphism of the species; in other mustelids, males consume the larger prey.

Comendo como uma menina: diferenças sexuais na dieta do furão (Galictis cuja) no sul do Brasil. O furão-pequeno é um mustelídeo hipercarnívoro amplamente distribuído na América do Sul, ocorrendo em uma variedade de habitats, incluindo estepes, desertos, campos, florestas e áreas úmidas. Todavia, há poucos dados científicos sobre a ecologia da espécie. Nesse estudo investigamos os hábitos alimentares de Galictis cuja na região do Pampa brasileiro, pela análise de conteúdo estomacais de indivíduos encontrados atropelados entre os anos de 2013 e 2023. Identificamos um alto consumo de mamíferos, encontrados em 80% das amostras e compreendendo 75% das presas consumidas. Anfíbios, répteis e aves são consumidos em baixas proporções. No que se refere aos mamíferos, apenas roedores foram encontrados, dentre os quais Cavia sp., Holochilus brasiliensis e Rattus sp. se destacam, correspondendo a 62% da biomassa ingerida. Apesar de não terem sido encontradas diferenças nas presas consumidas por machos e fêmeas, foram encontradas diferenças nos padrões de predação, com machos consumindo mais Rattus e fêmeas consumindo mais Cavia. Como resultado, machos consomem presas proporcionalmente menores (equivalentes a 1/6 de seu peso) do que as fêmeas (com presas equivalentes a 1/3 de seu peso). Isso é contrário ao esperado dado o dimorfismo sexual de tamanho existente nessa espécie e ao observado em outros mustelídeos, em que os machos consomem presas maiores.

Graphical abstract for the article “Eating like a girl: sex differences in the diet of the lesser grison (Galictis cuja) in southern Brazil” (B.M. Rodrigues et al., 2024)

Food habits of the ocelot (Leopardus pardalis) in a lowland Atlantic Forest of southeastern Brazil

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The ocelot (Leopardus pardalis) has a diverse diet and contributes to the control of animal populations at intermediate trophic levels, acting as an effcient mesopredator. Here, we characterized the diet of L. pardalis in a remnant of lowland Atlantic Forest of southeastern Brazil, determining the species and the main prey items consumed (those with a percentage of occurrence [PO] ≥ 5%), as well as its trophic specialization. We characterized L. pardalis diet using 30 fecal samples collected in the Vale Natural Reserve (Linhares/ES), between October 2014 and September 2016. Forty-nine food items were identified and distributed into 14 taxa, half of which were recognized as main prey (Cuniculus paca, Dasypus spp., Didelphis aurita, Mazama spp., Nasua nasua, Salvator merianae, and Sapajus robustus; 81.6% of the consumed items). Mammals were the most consumed (PO = 83.7%), followed by Reptilia (12.2%) and Aves (4.1%). Medium-sized prey (1–15 kg) were the most representative (PO = 84.9%), followed by large (> 15 kg; 10.9%) and small prey (< 1 kg; 4.3%). The diet was generalist when considering the consumption of individual prey (niche breadth = 0.641), but specialized in mammals (0.197) and medium-sized prey (0.181). High consumption of medium-sized mammals represents a foraging optimization strategy, as this prey type may be more energetically profitable for L. pardalis. The importance of some prey changed over time, suggesting temporal variation in the diet of this predator. We provided new information about the diet of the species, including the consumption of large prey (brocket deer of the genus Mazama). The local maintenance of a wide variety of prey may contribute to the conservation of this population over time.

Hábitos alimentarios del ocelote (Leopardus pardalis) en el Bosque Atlántico del sureste de Brasil. El ocelote (Leopardus pardalis) tiene una dieta diversa, que contribuye al control de las poblaciones animales de niveles tróficos intermedios y es un mesodepredador eficiente. Caracterizamos la dieta de L. pardalis en un remanente de Bosque Atlántico del sureste de Brasil para determinar las especies consumidas, sus principales presas (aquellas con un porcentaje de ocurrencia [PO] ≥ 5%) y la especialización trófica a partir de 30 muestras fecales recolectadas en la Reserva Natural Vale (Linhares/ES), entre octubre de 2014 y septiembre de 2016. Se identificaron 49 ítems distribuidos en 14 taxones, la mitad de los cuales fueron presas principales (Cuniculus paca, Dasypus spp., Didelphis aurita, Mazama spp., Nasua nasua, Salvator merianae y Sapajus robustus; 81.6% de los ítems consumidos). Los mamíferos fueron las presas más consumidas (PO = 83.7%), seguido de Reptilia (12.2%) y Aves (4.1%). Las presas medianas (1–15 kg) fueron las más representativas (PO = 84.9%) y presentes en todas las muestras, seguidas de las presas grandes (> 15 kg; 10.9%) y las pequeñas (< 1 kg; 4.3%). La dieta fue generalista en el consumo de presas individuales (amplitud de nicho = 0.641), pero especializada en mamíferos (0.197) y presas medianas (0.181). El alto consumo de mamíferos medianos puede estar relacionado con el hecho de que pueden ser más energéticos para L. pardalis. Algunas presas cambiaron su importancia a lo largo del tiempo, lo que sugiere una variación temporal en la dieta. Proporcionamos nueva información sobre la dieta de la especie, que incluye el consumo de presas grandes (cérvidos del género Mazama). El mantenimiento local de una amplia variedad de presas puede contribuir a la conservación de esta población a lo largo del tiempo.

Graphical abstract for the article “Food habits of the ocelot (Leopardus pardalis) in a lowland Atlantic Forest of southeastern Brazil” (dos Santos et al., 2022)

Selección de presas de Thylamys bruchi (Marsupialia, Didelphidae) en el Desierto del Monte central, Argentina

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Thylamys bruchi es un pequeño marsupial endémico de Argentina que habita el Desierto del Monte; es una especie nocturna y escansorial (i.e. utiliza estrato terrestre y arbóreo). Su dieta es omnívora con tendencia a la insectivoría, independientemente de las fluctuaciones en la disponibilidad de alimento. Este estudio tiene por objetivo evaluar la estrategia alimentaria de T. bruchi analizando estacionalmente la selección de presas y la amplitud de nicho trófico. El trabajo se realizó en la Reserva de Biósfera Ñacuñán, Mendoza, durante las estaciones húmeda y seca de 2014 y 2016. Este estudio se centró en conocer la composición de artrópodos de la dieta y para ello se analizó su consumo y su disponibilidad en el ambiente en las distintas estaciones. La dieta de esta especie presentó poca variabilidad estacional, con una composición de 70% artrópodos y 30% material vegetal. Se identificaron ocho órdenes y una familia de artrópodos, siendo Lepidoptera el más consumido. T. bruchi seleccionó lepidópteros (adultos y larvas) y ortópteros en todas las estaciones. La amplitud de nicho fue mayor en épocas de menor disponibilidad de presas, y menor cuando la abundancia fue mayor. Si bien T. bruchi presenta una estrategia alimentaria generalista, frente a los cambios estacionales en las presas incorpora la mayoría de los ítems disponibles y modifica parcialmente la composición de su dieta al aprovechar ítems más abundantes. Esta flexibilidad y el consumo de ítems alimentarios con mucha energía, como los artrópodos, permitiría que T. bruchi sobreviva en ambientes poco favorables como los desiertos.

Prey selection of Thylamys bruchi (Marsupialia, Didelphidae) in Central Monte Desert, Argentina. Thylamys bruchi is a small and endemic marsupial from Argentina which inhabits the Monte Desert. It presents nocturnal and scansorial habits (i.e. uses terrestrial and arboreal strata) and its diet is omnivorous with a tendency to insectivory, regardless of the fluctuations in food availability. The aim of this study was to evaluate the feeding strategy of T. bruchi seasonally, analyzing the selection of prey and the trophic niche breadth. Fieldwork was carried out at the Ñacuñan Man and Biosphere Reserve, Mendoza, during the wet and dry season of 2014 and 2016. This study focused on assessing the composition of arthropods in the diet. For this purpose, we measured prey consumption and their availability in the environment in the different seasons. T. bruchi‘s diet presented little seasonal variability, with 70% arthropods and 30% plant material. Eight orders and one family of arthropods were identified, with Lepidoptera being the most consumed item. T. bruchi selected Lepidoptera (adults and larvae) and Orthoptera in all seasons. Trophic niche breadth was greater in seasons with less prey availability and narrower when their abundance was greater. Although T. bruchi presents a generalist feeding strategy, in face of seasonal changes in prey abundance, it incorporates most of the available items and partially modifies the composition of its diet by exploiting more abundant items. This flexibility and the consumption of high energy food items such as arthropods may allow T. bruchi to survive in unfavorable and changing environments like deserts.