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Strategies to minimise intraspecific competition are common in wild animals. For example, individuals may exploit food resources at different levels of the food chain. Analyses of stable isotopes are particularly useful for confirming variations in an intraspecific niche because the chemical composition of animals tends to reflect both the food consumed and the habitats occupied by the species. However, studies using this methodology to investigate neotropical crocodilians are scarce. This study aimed to verify the existence of ontogenetic and sexual niche variation in broad-snouted caiman in a silvicultural landscape in Brazil through the use of carbon and nitrogen stable isotopes. The isotopic ratios of carbon and nitrogen were determined in claw samples collected from 24 juveniles, 8 adults, and 16 hatchlings of C. latirostris. We identified a discrete ontogenetic variation in the isotopic niche and sexual difference only for juveniles. These results may indicate differences in the exploitation resources and a consequent reduction in competition between age classes.

ABSTRACT. Ecological niche is the multidimensional space comprising the resources used by an organism. These results suggest that individuals of both sexes and throughout their ontogenetic development exploit food resources with the same isotopic baseline.

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Motivation SIA‐BRA is a data set that compiles stable carbon (C) and nitrogen (N) isotope ratios of terrestrial and aquatic animals sampled in Brazilian biomes and coastal marine areas. Stable isotope ratios are helpful in animal ecology for several reasons; for instance, they can be used to investigate trophic niches, energy sources (diet tracing) and to track migration patterns. The Neotropics are considered one of the most undersampled regions of the world. Given that Brazil is a continental country where most of the dietary ecology of animal species is under‐assessed, we believe that the SIA‐BRA can provide important complementary information to address this gap in the literature. Additionally, the SIA‐BRA data set allows future investigations to address many questions concerning diet tracing, habitat use, food webs, foraging ecology, physiological aspects and effects of phylogeny on dietary ecology. Main type of variable investigated Carbon and nitrogen stable isotope ratios for terrestrial and aquatic animals. Spatial location and grain The SIA‐BRA included animal tissues sampled in 964 sites in the main Brazilian biomes and coastal marine areas. Time period The data represent information published and/or sampled from 1984 to 2021. Major taxa studied and measurement level The SIA‐BRA contains isotopic data of c. 21,804 non‐captive wildlife specimens, excluding livestock production or laboratory experiments. They were 13,881 vertebrates and 7,923 invertebrates. They were divided into the following habitats: terrestrial (30% of the total), freshwater (27%), oceanic (40%) and estuarine (4%). There were 11 phyla, with a clear dominance of Chordata (64%) and Arthropoda (29%), 36 classes, 154 orders, 473 families, 894 genera and 1,157 species. Software format Data are supplied as a comma‐delimited text file (.csv).

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