Posted by: orcaweb | May 17, 2017

One species, many variations

Touchdown.jpg

Common dolphin and reflection

It’s the end of our seventh week on board already! The cliché is true; time is flying and I’m sure it is because we are having a lot of fun (working hard of course). After seeing my favourite species last week (pilot whales) I couldn’t wait to see what this week had in store.

As Jess and I bid farewell to Portsmouth last Wednesday and began our journey to Bilbao, we delivered our presentation to the passengers to let them know which species they might see the following morning. We then spent a couple of hours up on deck as we travelled through the English Channel; it was a beautiful, sunny evening and we were joined by numerous people keen to talk with us about the sightings the next day might bring.

Rainbow

One of many beautiful rainbows seen in the Bay of Biscay

I watched in wonder as a swallow darted and soared above us; they are such a joy to watch. Whenever I see them the lyrics of a heartwarming folk song I know called ‘Dark Swift and Bright Swallow’ are brought to my mind. The singer poetically reflects on the glee of seeing his first swallow of the year, one April day over the skies over Slapton Ley in Devon, as follows:

‘I was lifted above all care, as the swallows swum through the salted air,
Come from Savannah, and desert, and sea, to mark another year for me’

Having marvelled at these little masterful acrobats of the wind and sky, it was time to get a good night’s sleep ready for the wondrous wildlife of the water that we hoped to see early the next morning.

We were up on deck for 6am on Thursday as we passed over the deep, open waters (pelagic sea) in the Bay of Biscay. I was thrilled to find the sea state was a calm 1 – 2, which was very welcome after my previous week which featured some ‘choppy’ conditions! Our first sighting of the day was an ocean sunfish (Mola mola) which passed by very close to the ship. These bizarre looking creatures are the largest bony fish in the ocean. When at the surface, they turn on their side and drift along resembling a large pale dinner plate. When describing our sighting to a French colleague, I discovered that their name for this fish is ‘poisson-lune’ which means moon fish.

Sunfish.JPG

Ocean sunfish (Mola mola)

Moments later we saw a similar looking shape in the water and thought it might be another Sunfish. Unfortunately, it turned out to be a plastic bag. You can see why marine animals end up eating plastic litter; it often resembles fish, jellyfish or other prey.

Litter 1.JPG

Not a Mola mola!

On a more positive note, things then got very exciting. We were treated to relentless sightings of short-beaked common dolphins; in total we saw over 250 on this day! This was also the first day I saw dolphins from our cabin window. We are fortunate enough to see these stunning, sleek animals on nearly every crossing. Their distinctive hourglass-like marking on their flanks is the best identifying feature to look out for and this is usually clearly visible as the majority take an active interest in the ship, coming right alongside to play in the pressure waves given off by the movement of the boat and even diving right under it and out the other side. We are seeing a lot of calves with their mothers at the moment; I often wonder what the infant dolphins think the first time they see such a huge ship. I have no doubt that they trust their mothers know best and will keep them safe!

Three CDs.jpg

We had fantastic views of hundreds of common dolphins last week

Common dolphins seem to me to be the Labradors of the dolphin world, were they likened to a dog breed. They are reliable and often seem excited to see the boat, much to the delight of all who see them, which implies a ‘friendly’ character. It is a shame to call any animal ‘common’ I think, not least because some so called common species are becoming less so, making it a misnomer, but it also implies that they are somehow not very interesting. This certainly cannot be said of these beautiful animals.

With that in mind, in this post I wanted to write a little bit about the variation that I have noticed in the common dolphins we have observed. (In a book I am reading, written in 1989, they are referred to as ‘saddleback dolphins’ which is an alternative name for them). Without closer inspection, you could assume that all of these animals look so alike that there are no unique identifying features to tell them apart. However, as with all species of cetaceans, most have individual features, some more distinct than others, which allow them to be recognised from one another. Indeed, there are photographic records identifying members of various species throughout the world. One humpback whale sighted and photographed off Shetland in the UK was later sighted and identified as the same animal in the waters of Guadeloupe, over 4500 miles away in the southeast Caribbean! Photo records prove invaluable time and time again for discovering fascinating new things about these animals.

So, back to the lovely common dolphins of Biscay. Various aspects of a porpoise, dolphin or whale’s appearance can be used to identify an individual animal and here are some photographs to illustrate this.

The first photo here shows two dolphins; you can see that the lower of the two has evidence of a historic injury to the top of its tail stock, indicated by the indent and what seems to be well healed scar tissue. Conversely, it may be a defect present from birth.

CD with tail injury.jpg

In the next photo of two different animals, the top one has a visible circle shaped mark on its flank. This characteristic alone may not be distinct enough to identify an individual animal, but combined with other features (such as any notches in its dorsal fin) it could help to build a profile.

CD with scar

The photo below features another two different dolphins; there are numerous notable differences in appearance here, but the most striking is the notching in the dorsal fin of the animal in the foreground.

CD with dorsal notches

As you can see, there is indeed much variation among these animals. However common they may be, I will never tire of seeing these dolphins; there is a huge amount of variation between them and they are all unique individuals.

Additional cetacean sightings this week have included bottlenose dolphins, a distant large whale blow and two elusive beaked whales who disappeared before we could get a good enough look to identify them. However, on the last day of my two weeks on board we were treated to a view of some not so elusive beaked whales – three Cuvier’s beaked whales! One was a very battle scarred white male who shone like a beacon as he broke the surface of the water, the other two accompanying him were pristine looking females; perhaps he is assembling his harem, as is typical behaviour for these animals!

Cuviers

Two of the three distant Cuvier’s beaked whales that we saw

The highlight of my week was to come on this same brilliantly calm day. The clear waters afforded us over ten sightings of blue sharks! I had only ever encountered one of these beautiful animals prior to this and I was very excited to see so many. Here is a photo of one of the sharks we saw!

Blue shark

Perfect clear, calm conditions afforded us great views of numerous blue sharks

Other things we have enjoyed looking at this week included lovely rainbows at sea, a turtle dove and this beautiful but slightly bedraggled looking hummingbird hawkmoth which I found on the ship.

 

Hummingbird hawkmoth.jpg

Hummingbird hawkmoth

When I asked a French colleague for a cup in which to catch and release the aforementioned creature, he looked very concerned. It transpired he thought I had said that I had found a mouse on the ship! He was relieved when I showed it to him; for any future moth rescues I will be sure to use the French name ‘Papillon de nuit’ (butterfly of the night) to avoid confusion!

As I leave the ship for my week off I have land based wildlife watching and nature to look forward to. I wish my colleagues a week of great sightings and look forward to getting back on board!

Hazel

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