Bottlenose dolphin
Taxonomy
Class: Mammalia
Order: Cetacea
Family: Delphinidae
Genus: Tursiops
Species: Tursiops truncatus
Common Nam: Bottlenose dolphin
Description: Bottlenose dolphin has a medium-size robust body with a dark grey coloration dorsally to light grey laterally and light belly. The head has a sharp demarcation between the melon and the short rostrum. Adults range from 2 to 4 metres in length and can weigh from 150 to 650 kg. The size of individuals of this species varies considerably with the habitat and in general, individuals from temperate and tropical coastal waters tend to be smaller and have less body fat than individuals from colder pelagic waters.
Class: Mammalia
Order: Cetacea
Family: Delphinidae
Genus: Tursiops
Species: Tursiops truncatus
Common Nam: Bottlenose dolphin
Description: Bottlenose dolphin has a medium-size robust body with a dark grey coloration dorsally to light grey laterally and light belly. The head has a sharp demarcation between the melon and the short rostrum. Adults range from 2 to 4 metres in length and can weigh from 150 to 650 kg. The size of individuals of this species varies considerably with the habitat and in general, individuals from temperate and tropical coastal waters tend to be smaller and have less body fat than individuals from colder pelagic waters.
Habitat and distribution: Bottlenose dolphins are found in the temperate and tropical marine waters of the world, either in coastal waters or open ocean. Its capacity to live in captivity made him an ambassador of cetaceans within the general public and researchers. It can adapt to a variety of marine and estuarine habitats even ranging into rivers. Currently, there are thought to be two ecotypes of this species: an offshore form, common in the deeper waters or near oceanic islands, and an inshore form, which inhabits estuaries or bays. This latter may form groups that inhabit restricted coastal areas in a settled or residential pattern.
Global distribution (Wells and Scott 2002)
Feeding: The bottlenose dolphin feeds on a great variety of prey and is considered to be opportunistic. Despite this fact, it seems to show a preference for some families of fish, such as sciaenids, scombrids and mugilids, when the availability of prey so permits. Its diet is made up of various species of pelagic and bottom-dwelling fishes, cephalopods and crustaceans.
Reproduction: Sexually, females mature earlier (between 5 and 10 years of age) than the males (between 8 and 14 years of age). Females give birth to a single calf following a gestation period of around one year and with a minimum interval of two to three years between births. Although there are records of births throughout the year, there appear to be peaks in the warmer months. Lactation is the primary source of nutrition for the first year of life and may continue for several more months or years. The maternal investment in the young by this species is high and may last 3 to 6 years, the separation generally occurring with the birth of another calf.
Social Structure: Bottlenose dolphins generally live in small groups (2-15 individuals), although groups of several hundreds of individuals have been reported. Group composition tends to be dynamic, the age, reproductive condition, familial relationships, and affiliation histories apparently being the most important determinant factors.
In Madeira archipelago it is possible to sight this species year-round, although there is an increase in the number of sightings during spring and summer due to the presence of transient groups. Photo-identification studies carried out by the Whale Museum point to the existence of individuals that regularly use these waters, but it has not yet been established whether this is a case of a seasonal presence or permanent year-round residence.
Conservation status: The current conservation status for this species in the Autonomous Region of Madeira is Least Concern (LC – Portuguese Vertebrate Red List, ICN 2005). At the international level, the status set by the IUCN in 1994 is Deficient Data (DD). This species is included in Annex II of the European Habitats Directive.
Reproduction: Sexually, females mature earlier (between 5 and 10 years of age) than the males (between 8 and 14 years of age). Females give birth to a single calf following a gestation period of around one year and with a minimum interval of two to three years between births. Although there are records of births throughout the year, there appear to be peaks in the warmer months. Lactation is the primary source of nutrition for the first year of life and may continue for several more months or years. The maternal investment in the young by this species is high and may last 3 to 6 years, the separation generally occurring with the birth of another calf.
Social Structure: Bottlenose dolphins generally live in small groups (2-15 individuals), although groups of several hundreds of individuals have been reported. Group composition tends to be dynamic, the age, reproductive condition, familial relationships, and affiliation histories apparently being the most important determinant factors.
In Madeira archipelago it is possible to sight this species year-round, although there is an increase in the number of sightings during spring and summer due to the presence of transient groups. Photo-identification studies carried out by the Whale Museum point to the existence of individuals that regularly use these waters, but it has not yet been established whether this is a case of a seasonal presence or permanent year-round residence.
Conservation status: The current conservation status for this species in the Autonomous Region of Madeira is Least Concern (LC – Portuguese Vertebrate Red List, ICN 2005). At the international level, the status set by the IUCN in 1994 is Deficient Data (DD). This species is included in Annex II of the European Habitats Directive.
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