Common dolphin (Delphinus delphis) habitat preferences using data from two platforms of opportunity

Cetaceans are difficult to observe in the wild, and demand complex logistics for dedicated collection ofbiological data. As such, the distribution of most cetacean species is still poorly understood. Ecologicalniche models are useful in studying species distributions and their ecological determinants, and platformsof opportunity (e.g. commercial nautical operators) can provide an alternative source for that datain cetaceans. In this study, we modelled common dolphin (Delphinus delphis) habitat preferences usingecological niche modelling and presence data obtained from distinct platforms of opportunity in twodifferent areas in the Portuguese coast (west and south mainland Portugal) for the period 2005e2007.Models from southern Portugal were projected to western Portugal and vice-versa, to check forrobustness in predicting the species ecological niche. Our results show that data from platforms ofopportunity can result in robust ecological models and provide extremely useful information on cetaceanecology. We found that common dolphins exhibit a patchy distribution pattern over the Portuguesecoastline, and identified key habitats for their occurrence. The most important variable associated withthis species’ distribution was chlorophyll concentration which, given the results from previous research,we hypothesise reflects an ecological specialisation on pelagic schooling fish. Given that the mostabundant schooling fish species in Portugal is increasingly overexploited and in constant decline, moreattention should be given to the conservation of common dolphin in Portuguese waters.