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From the beach to the bench

As someone who thrives on being outside in dirt, fresh air, (almost all) weathers, and making imperfect crafts with very forgiveable materials, a closed, sterile laboratory requiring steady hands and utmost precision is a very unnatural environment for me. But needs must. Part of my PhD research requires samples which I collected from shags in the Falklands to be prepared and processed in the lab. And so, I was recently at the University of Aberdeen spending long, repetitive days chipping away at my stash of samples. For the most part, I was alone in the lab which meant fewer distractions and the freedom to swear when things went wrong, or sing along to the radio in order to entertain myself and retain some level of sanity. Another benefit to being the only person in the room meant that I saved myself some embarrassment when I was disproportionately excited to discover that my lab coat – which I’ve technically had for two-years now – has a special little pocket compartment just for pens. This also gives you a flavour of how exciting a week in the lab was for me. But my coat pockets have never been so well organised.

If you've got a mini centrifuge & a generator you can separate blood samples anywhere
Colourfully organised samples help to brighten up a day stuck indoors

The overall theme of my research is individual consistency in feeding behaviours; are some birds always going to the same places and eating the same things? And if so, why? I’m using a multitude of techniques to look at this, one of which is called stable isotope analysis.


You’ve possibly heard the phrase ‘you are what you eat’, and it’s quite literally true. Everything you eat is made up of carbon and nitrogen atoms (among other things). Some of these atoms, also known as isotopes, are heavier than others and as a result, they don’t decay over time and are therefore considered ‘stable’. The ratios of these stable isotopes in the environment varies from place to place, forming a type of fingerprint which we can measure and interpret.


Nitrogen accumulates up the food chain, so levels tend to be higher the further up you go. This can tell us if you’re a top predator, a plant eater at the bottom of the chain or somewhere in the middle. Carbon on the other hand, is more prevalent and variable in plants. Different types of plants have different ratios of stable carbon isotopes, which can tell us whether it's growing on land, by the coast or further out to sea. So, by looking at carbon and nitrogen isotopes, we can learn where in the food chain the shags are sitting (are they eating predatory fish or bottom feeding crustaceans?), and where they’re feeding (in shallow waters close to the coast or further out to sea?).



So where does individual consistency come into this? Well, because shags are what they eat, they accumulate these different isotopes in all bodily tissues, such as their organs, blood and feathers. I don’t want my birds to die for my research so we’re ignoring organs, but blood and feathers are easily collected with minimal stress to the bird. When we take a small blood sample we can separate the red blood cells from the plasma. Red blood cells are made every month or so, whereas plasma is made every two to four days, so from one blood sample we have two different time periods to assess the birds’ diet. Growing new feathers is a high energy task, so birds are very particular about when they do it. Adult shags tend to grow new body feathers during autumn/winter once they’ve finished rearing their chicks, and they’ll keep them until after the next breeding season. So, by collecting blood and feathers from birds at the same time in the breeding season, we can see if the birds’ carbon and nitrogen levels were the same in the previous 3 days, 30 days and 8 months.



Once my samples had been collected, cleaned and dried (the easy bit), I then had to prepare them for stable isotope analysis. Stable isotope analysis requires tiny portions, less than 1 milligram, of each sample. This is where the precision and swearing comes in. Only when you have to scoop teeny tiny spoonful’s of powdered blood into even smaller tin capsules do you realise how frustrating static can be. And only when you have to cut downy feathers into 1mm fragments do you realise how infuriating breathing can be, as you watch your precious feather samples take to the air with each exhalation. Patience is an incredibly valuable asset. But we got there in the end, and both my samples and I are now ready and waiting to visit a specialist lab where I’ll learn how to turn these trays of tiny, filled capsules into the all-important data that’ll tell us what these birds have been up to. Watch this space.


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