Interspecific interactions between short-beaked common, Atlantic spotted and striped dolphins in the Pico Island, Azores

• Autor(a) principal: Costa, Lara Rodrigues
• Data de Publicação: 2022
• Tipo de documento: Dissertação
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://hdl.handle.net/10400.1/19226
• topic: Associação; Açores; Cetáceos; Interações interespecíficas; Simpatria; Domínio/Área Científica::Ciências Naturais::Outras Ciências Naturais

The interspecific tendency of association is well known for many species, including primates, birds and cetaceans. While the exact factors that promote these interactions are still largely uncertain, it is highly probable that one or both species benefit from their association. Three cetacean species share the same habitat in the Azores and have the same feeding habitats, shortbeaked common dolphin (Delphinus delphis), striped dolphin (Stenella coeruleoalba) and Atlantic spotted dolphin (Stenella frontalis), being occasionally seen together. This project aims to evaluate these associations and determine the main factors influencing these interspecific interactions and their benefits. This study collected data in the surrounding waters of Pico Island, Azores, during seven consecutive years (2012-2018), using opportunistic platforms such as whale watching boats, that despite some limitations, have already been proven to be a way of cost-efficient data collection and a source of reliable data for research. A total of 1452 trips that resulted in 1289 sightings of Delphinus delphis, 317 sightings of Stenella coeruleoalba, 488 sightings of Stenella frontalis and a total of 82 interspecific interactions sightings (including at least two of these three target species) were analyzed, studying the behavior, bathymetry, distance to coast and presence of calves for each sighting. Statistical tests were performed to proceed to multiple comparisons between the drivers and the observations with and without interactions, revealing that in the majority of the statistical analysis only the striped dolphin had associations with the interactions, with the common dolphin showing less frequent associations and the spotted dolphin not showing any. The results showed that only the striped dolphin had an association with interaction and the main driver was concluded to be the increase of the foraging success, while the common dolphin showed to be driven by social reasons, such as the increase of the group size and the Atlantic spotted dolphin did not show any tendency to associate.