Ornitofagia em serpentes: revisão de literatura

Abstract

The snakes represent 3,709 of the current total 10,417 species of Squamata, ranging from fossorial to large constrictors, being found in all continents except Antartica. They are potential predators in many terrestrial, aquatic and marine communities. Consequently, information about their eating habits increases our understanding of trophic relationships at various ecological levels. The type of prey eaten may impose limitations to body size, locomotor behaviour, reproductive strategy and distribution, besides impacting daily activity patterns and habitat use. Considering that diet is recognized as a central factor influencing the evolution of snakes, this research will help elucidating some patterns related to ornithophagy in this group. The aim of the present study was to perform a data survey of predation on birds and their eggs by snakes. This will help identifying in which families these items occur, making it possible to infer the evolution of this trait by associating diet and phylogeny of the species. The dietary information of the species were obtained through an extensive literature review in books, and scientific notes and journals from Web of Knowledge, SCOPUS, and Scholar Google databases. Searching was performed using keywords, such as: snake diet, snake feeding, and bird predation. All data obtained were listed, being arranged into eight categories: 1. Family, 2. Genus, 3. Species, 4. Location, 5. Habitat, 6. Habit, 7. Snout-vent-lengh (SVL), 8. Diet. The total number of records was 367, with 261 snake species preying on birds and/or bird eggs. These results reveal a high incidence of the trait in the Colubridae family, with 33% of the species feeding on birds, mainly of the Colubrinae subfamily. Secondly comes the Viperidae (26%), followed by Dipsadidae (10%), Pythonidae (7,5%), Boidae (6.5%), Elapidae (6.1%) and Lamprophiidae (5%) families. These families include species with a wide variety of habits, with most of them presenting arboreal or semi-arboreal habits and diurnal activity. Besides that, the majority of the species are generalist snakes in which birds represents up to 10% of their diet. It is also evident a preference for preying nestlings or juvenile birds. Since snakes are usually alerted to the presence of their prey by chemosensory or visual stimuli, actives nests where birds are provisioning their nestlings at daylight, may draw more attention to potential predators. Furthermore, previous studies showed that diurnal nest predation events occur twice as often as nocturnal, correlating to the potential diurnal activity of the snakes. In summary, these results may contribute with future investigations in the field of snakes’ natural history.