Home range analysis of the semi-resident Bottlenose dolphin (Tursiops truncatus) population of Cardigan Bay (Wales)

• Autor(a) principal: Correia, Ana Rita Mendes Pinheiro
• Data de Publicação: 2017
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://hdl.handle.net/10400.1/10569
• topic: Bottlenose dolphin; Home range; Core Area; Kernel density estimators (KDE); Minimum Convex Polygon (MCP); Cardigan Bay

The common bottlenose dolphin (Tursiops truncatus, Montagu, 1821) belongs to the sub-order Odontoceti and is one of the most widely distributed species of cetaceans. Within this species it is possible to find strict resident populations, semi-resident populations or transient communities. The Cardigan Bay bottlenose dolphin population is one of the two semi-resident populations in the United Kingdom. With the increasing anthropogenic disturbance, particularly significant for cetacean communities whose geographic ranges are limited or decreasing, the survival of a certain population depends a great deal on its habitat. As a result, understanding the home range of a population is crucial in order to attempt any protection and monitoring measures. Also known as pattern of residency, the home range is the area where the individual spends its time feeding, breeding and nursing the young. The purpose of this work is to estimate the home range of the bottlenose dolphin population by comparing different group sets in order to infer if there are any dissimilarities between the distributions of the selected groups. Using photo-identification data from 2007 to 2016 obtained from surveys, combined with other information regarding the individuals, Minimum Convex Polygons and Kernel Density Estimators were calculated and mapped for each group and then compared. Both mean home range (95% KDE) and core areas (50% KDE) were inferred. Mean water depths were also determined for each group. No significant differences were obtained for gender, markings in the dorsal fin and presence or absence of calf. There were, however differences in distribution for the summer and winter sightings. Additional important areas for this bottlenose dolphin populations were determined, as well as seasonal differences in distribution. Further surveys are required, mainly at the areas outside the Special Areas of Conservation in Cardigan Bay.