{"id":50992,"date":"2020-05-28T09:56:30","date_gmt":"2020-05-28T10:56:30","guid":{"rendered":"https:\/\/whalewatchingazores.com\/blog\/?p=50992"},"modified":"2020-05-28T09:59:13","modified_gmt":"2020-05-28T10:59:13","slug":"distribution-and-potential-residency-patterns-of-bottlenose-dolphins-in-sao-miguel-island","status":"publish","type":"post","link":"https:\/\/whalewatchingazores.com\/blog\/distribution-and-potential-residency-patterns-of-bottlenose-dolphins-in-sao-miguel-island\/","title":{"rendered":"Distribution and potential residency patterns of bottlenose dolphins in S\u00e3o Miguel island"},"content":{"rendered":"\n

Bottlenose dolphins (Tursiops truncatus) are one of the species of dolphins that can be sighted year-round in the Azores. They are among the most sighted dolphins in our tours, and therefore we have plenty of chances to collect useful data about them on our trips. Some bottlenose dolphins are really well known since a long time ago, because of some special features or marks they have, as you can see in this article<\/a> written by our biologist Mariana Silva. However, in order to improve our knowledge about this species around S\u00e3o Miguel, a student from the University of Algarve, Rita Catal\u00e3o, has recently joined our team and decided to study bottlenose dolphins for her Msc. Thesis.<\/p>\n\n\n\n

The definition of population describes a group of organisms of the same species occupying a particular space at a particular time. However, individuals from the same population can have different ranging patterns and move differently, showing different site fidelity, and therefore, with different impacts on population distribution and abundance, habitat selection, interactions with other species, and social structure (Defran et al., 1999; B\u00f6rger, 2016; Nathan et al., 2008). Whether they stay in the same area or leave, their movements are usually driven by the distribution of limiting resources like food, mates, nursery, resting and predator avoidance areas<\/strong> (Nathan et al., 2008; Silva et al., 2007). Species with high site fidelity and restricted ranging patterns to be more vulnerable to population declines due to local threats (Warkentin & Hern\u00e1ndez, 1996; Atkins et al., 2016).Therefore, it is important to define key areas for each species<\/strong> so that appropriate conservation measures can be applied according to the needs of the populations (Herfindal et al., 2005).<\/p>\n\n\n\n

Photo-identification is now a very commonly used technique in the study of species abundance, site fidelity, movement patterns and social structure (W\u00fcrsig & Jefferson, 1990). Its first application on cetaceans occurred in the early 1970s, and since then the data taken from this technique has been continuously growing (Neumann et al., 2002), particularly with the implementation of digital photography. Natural marks that are considered distinguishable are used to identify individuals, instead of physically capture the animals, proving to be very effective and non-evasive (Evans & Hammond, 2004; Neumann et al., 2002).<\/p>\n\n\n\n

In the Azores, several studies have been conducted on this species about ranging and residence patterns, occurrence and distribution, survival and abundance. However, although a lot of data has been collected throughout the years, only a few studies have been done focusing mainly on social structure, in the central group islands (Silva et al., 2008) and on habitat preference around S\u00e3o Miguel Island (Fern\u00e1ndez et al., 2018; Gonz\u00e1lez Garc\u00eda., 2018).<\/p>\n\n\n\n

\"Bottlenose
Bottlenose dolphin (Tursiops truncatus)<\/figcaption><\/figure><\/div>\n\n\n\n

To analyse the distribution of bottlenose dolphins and create a photo-identification catalogue of the individuals sighted around S\u00e3o Miguel, a 10-year sightings dataset (2010-2019) and a 6-year photographic dataset (2014-2019) collected on board Futurismo\u2019s whale watching vessels, are used.<\/p>\n\n\n\n

\"Rafael
Marine biologist taking pictures of the animals<\/figcaption><\/figure><\/div>\n\n\n\n

For the catalogue we use dolphins with distinctive nicks\/notches, marks\/scars and\/or extensive pigmentation on the dorsal fin.<\/p>\n\n\n\n