“I recognise that dolphin” … “And that one” … uttered by me but still sweet music to my ears. Its hugely exciting when we spot a pod of dolphins and even more satisfying when through the cameras lens I recognise an individual that we’ve seen several years before. Obviously I can only confirm the match once I’ve downloaded all the images and double and triple checked it against the catalogue but some Risso’s dolphins have such unique markings that when you see them again, you just know that you’ve seen him/her before. Recognising one dolphin is inspiring but recognising two, three or ten dolphins in one pod is fantastic, especially when we first identified them back in 2010, also in the same pod. Is this a family group? Have they been together all this time? These are only some of the multitude of questions that these encounters raise.
Below are images of “Seaweed” the Risso’s dolphin taken first in 2010, and then again in 2013 – can you see the similarities and also the differences?
Identifying new animals in a group is also really exciting, especially when they’re with animals that are already known to us. Are these new relationships? Were they around these waters before and just eluded the camera? So many questions!!
So far this year, we’ve resighted 10 animals from previous years, one of which was accompanied by a youngster. Back in 2010 when we first identified her, we didn’t know if she was a she or a he but this time, given the fact that she was closely accompanied by a calf, we can be fairly confident that she is a she after all. Whether or not this is her first calf, we’ll likely never know but the fact that she has returned to the area with her youngster in tow, speaks to the fact that these waters are important to her and the long-term health of her and her calf.
New animals are being added to the catalogue all the time and this year alone we’ve identified another 10 animals to add to the existing catalogue – all of whom were with the dolphins already known to us. One of these animals was accompanied by a youngster (so we can assume that she too is a she) and it’s heartwarming to see such a large group, frolicking in the deep blue and more so, approaching the boat and checking us out, like these mother’s and their juvenile calves below.
Identifying individual Risso’s dolphins can sometimes be a tricky business but it’s the only way for us to be able to show that these animals are coming back again and again. As with a lot of other dolphin species, the main identifying feature of a Risso’s dolphin is the dorsal fin. The shape and size of the fin, unique colouration, scratches and nicks, all help make up a picture of each individual animal. When Risso’s dolphin calves are born they have an olive-brown-grey tinge to their skin. Over time this darkens and then as they become older their body becomes more white. Risso’s are very sociable animals and most of the scars and scratches are caused by the teeth of other Risso’s dolphins, sometimes resulting in very distinctive markings which make my job a lot easier. At the same time, these marks can change dramatically over time, some fade away, some are covered up by newer scratches so trying to match animals over several years is a time-consuming job and tiring on the eyes. However, it’s the only way … and so during every encounter, we take as many photographs of individual dorsal fins as possible, and then spend the following days analysing these images with a very keen eye. Below are images of “Spider” the Risso’s dolphin in 2010, and then again in 2013 – can you see the similarities and also the differences?
We’ve been coming to Lewis for four years now, and have a catalogue of over 50 animals, some of which have been resighted within one individual field season – showing that they stay around the area for some time and are not just passing through – and some which have been resighted over the years – showing that they continue to return to this important area.
As Sarah pointed out in our last blog from our field site here on the Isle of Lewis, we plan to demonstrate that this area is important to Risso’s dolphins and other species, and that it should be recognised and protected as such. To this end, we need to show that the same animals return to this spot year after year, and that they bring back their young calves. All of these encounters, and the resulting matching of photographs is helping us to make our case for protecting this unique habitat for years to come.