Spot the difference

One of the hardest parts of fieldwork here is identifying individuals that have been studied in previous years. This is important to see whether the individual behaviour patterns we observe are repeatable across time, or whether they change over time, for example with an animal’s age or condition. Getting repeats from the same individuals is possible because female grey seals are very faithful to their breeding site, often returning to the exact same spot where they raised a pup the year before.

Seals that have been studied in previous years have a small orange tag concealed between two ‘toes’ of their rear flipper. These are designed to be as inconspicuous as possible, to make sure that they do not have any effect on the animal as it goes about its daily life. However, this also makes them extremely difficult to spot. Sometimes, you’ll be watching a seal for four hours as you video the one next door, and just as you are about to leave, it stretches its flippers out and you get a flash of orange that has been hiding the entire time. They’d definitely win at hide-and-seek!

Spotting the tags is not the most difficult part, however. Once you’ve found the tag, you have to take a photo to try to identify it. Photos are compared to those taken of seals seen in the same area, both earlier this season and in previous years. It’s like the biggest and most difficult game of spot the difference that you could ever imagine. If you don’t believe me, try it for yourself: the six photos below are of just three seals – can you match up the pairs? (Answers at the bottom of the page)













There are a few experts on the island who seem to magically be able to look at two photos of seals and immediately tell whether they are of the same seal or not. One of their secrets is to find a spot and look at the pattern immediately around it. They then to try and find the same spot and surrounding pattern on the other photo. This is easier than looking at the photo as a whole, because it doesn’t overwhelm you with too much information, which blocks your ability to recognise the differences. It’s also useful if you can see the patterns both ways – as dark spots on a lighter background, but also as lighter patterns on a dark background – this way you are likely to see more ‘memorable’ patterns. Even doing it this way though, is a lot easier said than done – often the seals are entirely covered in mud, stretched out in one photo and not in the other, or seen from completely different angles!


One to test even the experts…..


A and D

B and E

C and F


Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Google+ photo

You are commenting using your Google+ account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s