Bottlenose dolphins-The big boys club

by Matthew Norton

The open ocean offers a whole world to explore, provided you belong to a species of strong swimmers. There is however, a big difference between swimming to a new place and surviving there, which is why you can find big differences between groups of animals who live in different environments, even though they belong to the same species.

The bottlenose dolphin is one such species that has populations living all over the world with dramatic differences in body size. In Florida they reach a length of 2.5m which is rather unimpressive compared to world’s largest bottlenose dolphins, which can be found in the Moray Firth in Scotland and reach lengths of almost 4m. These Scottish dolphins are so big because it’s much colder in Scotland (I’ve noticed) and by having a larger body they can hold a thicker layer of fat under their skin (blubber) to keep themselves warm. It is also worth noting that they can throw their weight around while attacking porpoises and other dolphins. It is very unlikely that you would be attacked by a wild dolphin, but best not to make them angry.

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It is remarkable to think that bottlenose dolphins from the Moray Firth (left) can grow so big. It’s hard not to feel sorry for the harbour porpoise that they attack (right).

These big bottlenose dolphins need lots of food to sustain their body size, so it’s a good thing they are such effective hunters with their ability to use sound to find fish (echolocation) and sharp pointy teeth for catching them. They are also ‘opportunistic feeders’ which means if it’s fishy and they can catch it, they will eat it, but at the same time they are strategic with their feeding habits. In the Moray Firth you have a better chance of seeing bottlenose dolphin from the shore during the summer because they are hunting fish that come close to the shore, such as salmon swimming up and down the rivers. In the winter, they spend more time hunting other species of fish that gather in deeper waters, such as mackerel.

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The diet of a bottlenose dolphin includes (from the top) salmon, cod, haddock, herring, mackerel, sardines and more.

Moray Firth bottlenose dolphins are also opportunistic in the sense that they are still exploring with members of this population having been spotted further down the east coast in places like Aberdeen, St. Andrews and even northeast England, I hear Scarborough is especially popular. More recently dolphins from the Moray Firth have been spotted even further away in the Netherlands and around the coasts of Ireland. We know these dolphins came from the Moray Firth because we can track individual dolphins using photos of their dorsal fin which has a pattern of scratches, cuts and other markings that is unique to each dolphin (sort of like a fingerprint).

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Most of the (roughly) 200 bottlenose dolphins that live in the Moray Firth stay in this area all year round, as far as we know.

At the moment I don’t think anyone knows for sure (as of October 2019) why bottlenose dolphins are leaving the Moray Firth, but allow me to speculate on some possibilities. They may be struggling to find food in the Moray Firth and have gone looking for new feeding grounds. They may be trying to avoid inbreeding, which can cause all kinds of problems, by looking for other bottlenose dolphins to reproduce with. It is also possible that the environment is changing in the Moray Firth and is slowly driving them away, those who have already left may be ahead of the curve. I hope this isn’t the case; I have met many people in Scotland who are delighted to have these dolphins around.

Bottlenose dolphins are often described as being very intelligent animals, which is amazing, but this makes it more difficult to work out what they are doing and why. Maybe there is a perfectly logical reason why they explore, or don’t explore, the oceans of the world, but it is possible that they do it because they can.

From a human perspective

Watching whales, dolphins and porpoises in their natural habitat is one of the best life experiences you could wish for and Scotland is a great place to do it. As well as bottlenose dolphins, the Moray Firth is home to harbour porpoises and minke whales regularly visit during the summer, while along the Scottish coastline you can see over 20 different species including common dolphins, risso’s dolphins and orcas.

At Spey Bay (on the coast of the Moray Firth) you will also find the Scottish Dolphin Centre, which is run by a global charity called Whale and Dolphin Conservation (WDC) that is really pushing for the protection of whales and dolphins (and porpoises). I know the centre and WDC very well because for the last 8 months I have volunteered there as a residential guide and education volunteer (I should make it clear that they did not ask me to write and all opinions in this article are my own). This role was split between working ‘front of house’, running the shop and exhibition area, delivering tours and talking to people about whales and dolphins and WDC, and helping with the education programme, which involved running school activities, delivering community talks and planning holiday club activities. That last one was particularly fun because I had a lot of creative freedom, but there was the risk of all hell breaking loose, especially when water pistols were involved.

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The Scottish Dolphin Centre is the public face of Whale and Dolphin Conservation where we can talk to people face to face on a day to day basis about whales and dolphins and the work that WDC is doing to protect them. It adds an extra layer of engagement that is not so easy when you’re just working from the office. The café and their delicious cakes is also a significant bonus.

The Scottish Dolphin Centre was set up long before I came along, but I would still say that it breathed new life into the area and has raised awareness of the heritage and the local wildlife (other than dolphins). The centre itself was once a salmon fishing station that processed the fish caught in the river and sea. There is also an icehouse on site, the largest still standing in Scotland, for storing ice that was packed with the fish to keep them fresh at market. Today the icehouse is used as another exhibition area with immersive video rooms, old fishing and ship building tools and a room full of impressive whale and dolphin bones.

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The icehouse (left) was part of a massive fishing operation with thousands of salmon caught a day at its peak. This all ended in the 1990’s, but the river is still a beautiful place to visit and the fish (that survived us) bring dolphins, seals, otters and ospreys every year.

Reading through this article you are probably thinking that I am biased in favour of the Scottish Dolphin Centre and WDC, and you are probably right. So in the interest of balance I will admit that not every visitor was as impressed as I was when I first walked through those doors, but is a common fact of life that you cannot please everyone. In particular, some people were disappointed that they were not guaranteed to see bottlenose dolphins during their visit. However, all wild animals are unpredictable and WDC is firmly against keeping whales and dolphins in captivity. Besides, there are few things more special than that chance to see them in the wild where they belong.

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Thanks for reading

Sources

Wikipedia. 2019. Common bottlenose dolphin. https://en.m.wikipedia.org/wiki/Common_bottlenose_dolphin. Last accessed 05/11/2019

Whale and Dolphin Conservation. 2019. Common bottlenose dolphin. https://uk.whales.org/whales-dolphins/species-guide/common-bottlenose-dolphin/. Last accessed 05/11/2019

Connor et al. 2000. THE BOTTLENOSE DOLPHIN: Social Relationships in a Fission-Fusion Society; Cetacean Societies: Field Studies of Dolphins and Whales. ISBN 9780226503417

Connor et al. 2004. Aggression in bottlenose dolphins: evidence for sexual coercion, male-male competition, and female tolerance through analysis of tooth-rake marks and behaviour

Parsons et al. 2003. Male-male aggression renders bottlenose dolphin (Tursiops truncatus) unconscious

Ross and Wilson. 1996. Violent interactions between bottlenose dolphins and harbour porpoises

Santos et al. 2001. Stomach contents of bottlenose dolphins (Tursiops truncatus) in Scottish waters

Hastie et al. 2004. Functional mechanisms underlying cetacean distribution patterns: hotspots for bottlenose dolphins are linked to foraging

Patterson et al. 1998. Evidence for infanticide in bottlenose dolphins: an explanation for violent interactions with harbour porpoises?

Ross Shire Journal. 2019. Moray Firth bottlenose dolphin Spirtle surprises experts after being spotted off south-west Ireland. https://www.ross-shirejournal.co.uk/news/moray-firth-dolphin-surprises-experts-after-being-spotted-off-south-west-ireland-180460/. Last accessed 05/11/2019

Evening express. 2019. Moray Firth dolphins spotted in Netherlands and Ireland. https://www.eveningexpress.co.uk/fp/news/local/moray-firth-dolphins-spotted-in-netherlands-and-ireland/. Last accessed 05/11/2019

Scottish Dolphin Centre. 2019. https://dolphincentre.whales.org/. Last accessed 05/11/2019

Image sources

Shirehorse. 2007. [CC BY-SA 3.0 (http://creativecommons.org/licenses/by-sa/3.0/)%5D. https://commons.wikimedia.org/wiki/File:2005-05-n2-2549.jpg

Hogweard. 2012. [CC BY 3.0 (https://creativecommons.org/licenses/by/3.0)%5D. https://commons.wikimedia.org/wiki/File:Moray_Firth_Map.png

All other images are public domain and do not require attribution

One thought on “Bottlenose dolphins-The big boys club”

  1. Great descriptions of types of dolphins , their environment , and questions and answers about their travel around uk and Europe. Also the great work at the Whale & Dolphin conservation centre. Thanks Matthew.

    Lin N

    Like

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