You may have seen at the beginning of the year that an unusual visitor came to Cardigan Bay, more specifically, New Quay harbour. Spotted in January dancing in rough waves “stormy” the short-beaked common dolphin became a local celebrity.
Short-beaked common dolphins normally prefer deeper waters along the continental slope. As you may know, Cardigan Bay has one of Europe’s largest semi-resident populations of bottlenose dolphins, a species which are larger than the common dolphin. Here are some comparisons:
|Bottlenose dolphin||Common dolphin|
|Length||2.5-4 m||2.1-2.4 m|
|Appearance||Light grey to black, with a lighter colouration on the belly. They have a robust body and a short, thick beak.||Distinct bright coloration and patterns: a dark grey cape along the back that creates a “V” just below the dorsal fin on either side of the body, they are yellow/tan along the flank and white underneath.|
|Lifespan||40-50 years||About 35 years|
|Diet||Opportunistic feeders; a wide variety of schooling fish, invertebrates, squids.||Opportunistic feeders; fish, mostly schooling fish and cephalopods (squid)|
Similar to bottlenose dolphins, short-beaked common dolphins are normally very social, the difference being that they’re usually found in large groups, sometimes including hundreds of individuals. They are also very active at the surface; they display energetic routines together of breaching, tail slapping and bow riding the wake of boats. So it was a surprise to us here at Sea Watch to see ‘Stormy’ all alone.
The “solitary dolphin phenomenon” is a behaviour not yet fully understood by scientists. Studies have shown that some cetaceans, which find themselves alone, have their behaviour reinforced by people who try and interact with them, eventually becoming reliant on the human contact. However, there are a number of possible reasons why a cetacean may be alone in the first place. It may have been spatially separated by choice or via one, or many environmental and man made pressures, such as food availability, habitat destruction, predation presence, reproductive strategy or human interference. In some cases, solidarity is only temporary, perhaps triggered by the loss of a companion or group.
Solitary dolphins typically stay in a particular region for an extended period of time, and have certain localities within this range that they regularly frequent. Unsurprisingly… people will often flock in large numbers to see the dolphins (maybe try and touch or swim with them), over time solitary dolphins become ‘habituated’ to people. Research has shown that there are a series of stages that solitary dolphins typically progress through.
The dolphin appears and remains in a new home range, sometimes restricting itself to a small, protected part of the range often < 1km2. Dolphin may follow boats (usually fishing boats) or inspect fishing gear, but does not yet approach humans.
The dolphin becomes habituated to new range and may start to follow boats. Local people aware of its presence may attempt to swim with the animal. Dolphin appears curious but remains at a distance from swimmers. May bow ride or inspect ropes, chains and buoys, etc.
The dolphin becomes familiar with the presence of one or more people who have deliberately attempted to habituate it – this process may be assisted or even initiated by the dolphin. At this stage, the dolphin interacts with only a limited number of people in the water. Behaviour may include swimming in close proximity or diving side by side; the dolphin being touched including having its dorsal fin held to allow swimmers to be pulled along by the animal.
The presence of the animal becomes widely known, often assisted by media exposure. It becomes a local celebrity and tourist attraction, attracting visitors. During this stage, inappropriate human behaviour may provoke unwanted and possibly dangerous behaviour in the dolphin, including dominant, aggressive and sexual behaviours directed at humans. Unfortunately, the animals’ fascination with people (and visa versa) often gets the animals into trouble. The dolphins are large powerful marine predators and they may accidentally (or deliberately if they are frightened or frustrated) injure people in the water particularly by biting or butting but sometimes also just by trying to swim around them. There is also a risk of disease transmission. (Stages taken from uk.whales.org)
Stormy was last seen on 15.04.15 in New Quay Harbour, also nicknamed “Daily” as he was seen everyday for over 3 months, we are really interested in where he’s got too.
So if you happen to see Stormy the solitary short-beaked common dolphin, please let us know via our sightings network. We’d also love to see some pictures of his journey or new home.
by Beth Byrne, Sea Watch Foundation Research Intern.