Familiar faces in Orkney

The second year of photo-identification collection has officially started in all three study sites, with Andy going out on the boat seal trips at Dunvegan Castle, Craig having settled in beautiful Kintyre coast and myself checking on the seal haulouts in Orkney. The first taste of photoID in Orkney was during our trip earlier in April to capture and release harbour seals in order to collect individual data on health condition as well as to deploy telemetry tags.

Harbour seals are so well camouflaged against the rocky shore! There are ~15 seals in this picture, can you see them?

During the first day out taking pictures we came across a group of 17 seals hauled out in Burray. I managed to photograph around 14 of those but had to give up on a few that were so comfortably sleeping that would not move at all to give me a view of the pelage pattern in their head. Once back in the office I checked the pictures and realized that I already had 13 of those seals in the catalogue of seals from last summer!

For example we saw Or146, a male harbour seal already photographed in 2016, who actually was seen fighting with another male last summer, as seen in the second video in this blog entry from last year.

Or146, a male harbour seal, seen on 16th April 2017

Or146 seen on 21st May 2016

We also spotted a known female, Or020, who we captured and released last year and then subsequently photographed during the pupping season. Last summer she had a pup, and by the looks of it she is likely to be pregnant again.

Or020, a female seen on 8th July 2016 with her pup to her right

Or020 seen on 16th April 2017

We also saw a couple of younger seals, which sometimes prove a bit more difficult to identify if their spot pattern in the pelage is not so well defined. However, that was not the case for this little female, Or105, already photographed last summer.

Or105 seen on the 10th June 2016

Or105 seen again on 16th April 2017!

We have not seen pups yet, but the first one cannot be far away from being born as the haulouts fill with pregnant females. Last week I photographed Or045, a known female from last summer, who had a pup last year and is currently very pregnant, as you can see in the photograph below.

Or045 looking very pregnant on 9th of June 2016

Or045 with her pup in 2016 (picture taken on 20th June 2016)

Or045 looking very pregnant this year (picture taken on 5th June 2017)

Information such as this will be recorded on an annual basis for all known and new females that enter the catalogue, and will help build up a database of information on which females were seen each year and whether they were seen with a pup or not. We will use such data to estimate birth rates in the different study sites. We can then compare those birth rates in study sites of contrasting population trajectories (e.g. study sites where the number of harbour seals have been declining or where they have been stable or increasing), which on its own will be very interesting given the very different population trajectories at different study sites (e.g. Orkney versus Isle of Skye). These birth rates together with survival rates that we will also estimate from the photo-ID data, can inform a population model for harbour seals. This model, which simulates what happens in a population over time, can be tweaked around with different scenarios of birth and mortality rates to understand which scenarios might be representative of the different population trajectories.

Meanwhile we will be going out to take pictures on a daily basis when the weather allows, counting the days until the first pup shows up… That day can’t be far given the activity in some of the females bellies! Check this wriggly pup in the video below:

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