Resumo: A jiboia (Boa constrictor) é considerada um predador de topo e a sua dieta inclui uma grande variedade de aves, mamíferos e outros répteis, todos relacionados diretamente com a sua disponibilidade no ambiente por ela habitado. Sete jiboias foram encontradas atropeladas em estradas no entorno de unidades de conservação da região semiárida do estado do Rio Grande do Norte, no nordeste brasileiro. O seu trato digestivo foi analisado de modo a identificar itens alimentares e a classificá-los de acordo com a sua orientação no trato. De entre os itens alimentares encontrados, o gambá-de-orelha-branca (Didelphis albiventris) e o teju (Salvator merianae) foram ingeridos no sentido ântero-posterior, enquanto que dentes de punaré (Thrichomys laurentius) e de preá (Galea spixii) e pelos de um roedor não identificado foram encontrados do trato intestinal. Dois itens novos foram identificados: a rolinha-de-asa-de-canela (Columbina minuta), que foi ingerida no sentido póstero-anterior, e sementes de carnaúba (Copernicia prunifera). A orientação dos itens (ântero-posterior ou póstero-anterior) seguiu o que era esperado para cada tipo de presa. A presença de sementes de carnaúba indica que, além de ser um predador de topo, a jiboia também pode ser um potencial dispersor de sementes, o que constitui um papel ecológico previamente não descrito para esta espécie.

Abstract: The boa (Boa constrictor) is considered a top predator and its diet includes a wide variety of birds, mammals, and other reptiles, all related directly to their availability in the environment inhabited by the snake. Seven boas were found roadkilled on highways adjacent to conservation units in the semi-arid region of Rio Grande do Norte state, in northeastern Brazil. Their digestive tract was analyzed to identify food items and classify them according to their orientation in the tract. Among the food items found, the white-eared opossum (Didelphis albiventris) and the black-and-white tegu (Salvator merianae) were ingested head-first, while teeth of a punaré (Thrichomys laurentius) and a Spix's yellow-toothed cavy (Galea spixii) and hairs of an unidentified rodent were found in the intestinal tract. In addition, two novel items were identified: the plain-breasted ground-dove (Columbina minuta), which were ingested tail-first, and carnauba palm seeds (Copernicia prunifera). The orientation of the prey (head-first or tail-first) followed what was expected for each type of prey. In addition, the presence of carnauba palm seeds indicates that, while being a top predator, the boa may also be a potential disperser of seeds, which would constitute a previously unrecorded ecological role for this species.

The Coscoroba Swan, Coscoroba coscoroba (Molina, 1782), is a poorly known aberrant Anserine endemic to South America. We captured adult birds (189 male, 157 female) from the largest population in Brazil at the Taim Ecological Reserve, State of Rio Grande do Sul, Brazil. Different patterns between sexes can reflect differences in selection, and positive allometry may indicate that a character is sexually selected. We used body weight and 10 morphological measurements to examine allometric differences between males and females of C. coscoroba. Males were consistently larger than females. Analysis of scaling relationships against body mass showed that nostril, tail, wing and bill height were positively allometric (i.e., heavier birds had relatively larger character lengths), but there were no sexual differences in allometric slopes. However, for a given mass, mature females had longer tails, longer wings (up to metacarpophalangeal articulation) and shorter heads than males. In the light of current debate in the literature, we discuss whether such positively allometric traits and sexual differences in scaling may be indicative of sexual selection. Although Coscoroba Swan is a monogamous species, increasing the size of some attributes may confer some advantage for mate selection or male-male competition and, contrary to other studies, we suggest that positively allometric slopes alone should not be considered as evidence for sexual selection of the considered traits.