Secrets in a Stomach

A few weeks ago I travelled to the Netherlands. Not the typical trip to Holland that perhaps others on the plane my age had chosen: I was quickly on the top deck of a train (double decker trains?!) travelling north, away from Amsterdam. One bus, one ferry and a car journey later I’d reached my destination: Texel (pronounced Tessel), the first and largest of a string of islands off the Dutch coast. Texel is a popular holiday destination amongst Dutch and Germans, however I was not there to enjoy its long sandy beaches. Instead, I was there along with several others to dissect fulmars for the weekend!

To many, I’m sure, there are better ways to spend a weekend than constantly smelling like dead birds… however I really enjoyed it (not the smell – the weekend!). As well as doing some useful science, it was pretty sociable too! But anyway, back to the reason we were there: fulmars.

Northern fulmars are seabirds that gracefully roam the ocean waves, only returning to land to breed. They soar on stiff wings, searching for anything near the surface to eat: fish, squid, worms, jellyfish… they’re not fussy. However, this non-specific diet that historically served them so well now puts them at a disadvantage. Because of humans. We use plastic, and then we throw it away, at least a lot of it. This plastic makes its way into the sea (this wet wild, stormy weather we’re having now will probably blow some into the sea, for example) and when it gets there, most of it floats. Floating just as a fulmar’s natural food would do, plastic is easily mistaken for something edible. And sure enough, most fulmars we see have plastic in their stomachs (to be precise, 98.6% of fulmars in the English Channel have ingested plastic).

Back to Texel: I was attending a workshop held by a Dutch research group that is monitoring the amount of plastic ingested by fulmars that have, mostly, washed up dead on beaches. Once fulmars eat plastic, they do not regurgitate it (as a gull would, for example) but they keep it in the muscular part of their stomach. When it has broken down into small enough pieces it can pass out through their intestines. Because of this, the plastic in their stomachs when they are dissected represents roughly what they ate during the last month before they died.

It’s worth mentioning that the plastic may not be directly killing the bird. Of course, if a bird’s stomach is completely full of plastic then they wont have room for any food, and they can quickly become dehydrated. However in the winter, stormy conditions at sea make all feeding difficult, and therefore many can starve because of natural causes. Therefore, our sample of how much plastic an individual has eaten is not necessarily biased towards those with high amounts. The actual effects of plastic ingestion may be much more subtle, such as uptake of harmful chemicals, but this is a much trickier research area and something that I am working on. Watch this space…!

So every 18 months or so, a group of us that share a mutual interest get together to dissect the new fulmars that volunteers have found on beaches around the north sea since the last workshop. We check every bird for injuries and signs of pollution, the stage of feather moult (fulmars replace their old, worn feathers every year) and development of reproductive organs to assess age, whether they’re male or female, and finally the condition of their energy reserves and vital organs. We then take out the stomach to look for plastic at a later stage. Not only is it a useful opportunity to carry out the research in a sociable way, but it is a great chance for everyone to improve dissection skills and check that our methods are all comparable: vital when comparing the resulting data!

The group leader and fulmar-plastic-ingestion-monitor since 1980 (!), Jan Van Franeker, first dissected a fulmar from the Shetland Islands as an example. It was a chick that had been hit by a car (in the Shetland Islands, fulmars have to cross roads on their way from breeding colonies on cliffs to the sea). His parents had prepared him well for his first winter at sea: nearly 2 centimetres of fat covered his entire body and he weighed nearly 1.4kg! This is in comparison to most birds we see that have starved to death, which have little or no fat, and an adult male weighs roughly 800g. Even by healthy standards 2 cm of fat is a lot! So it was sad to see that this chick had died before even reaching the ocean, after his parents had invested so much in raising him to this stage, but I guess that’s life for a fulmar chick, and surviving the first winter is the hardest part. Worse was still to come: he had plastic in his stomach, arguably not part of natural life for a fulmar chick. Most likely his parents will have picked it up at sea and then fed it to him, thinking that it was food to help in his preparation for winter.

Enthusiasm over a dissection demonstration. Photo: Stephan Weiel

Of course no tale of a fulmar starving at sea or being hit by a car is a good one, particularly if he was a newly born chick, or if she was about to lay an egg (as my first fulmar at this workshop was). However we can at least be grateful that each individual dissected in our workshop has provided a vital piece of information about the state of plastic pollution in our oceans. This in turn can be passed on to our governments, which are committed through international legislation to reduce the amount of plastic that is found in stomachs of northern fulmars.

On an aside, on the last day of our workshop we went to a seal rehabilitation centre followed by some bird watching (ok I admit: not all work for the long-weekend, we did get a chance to enjoy the island!). The seal rehabilitation centre, ecomare, aims to reintroduce seals to the wild following illnesses or injuries or whatever. If the seals are blind, though, then they keep them in captivity – after all it wouldn’t be very kind to do anything else! They also keep seals that haven’t been taught properly by their mother to feed, and therefore cant fend for themselves in the wild, sometimes repeatedly washing up on beaches. These seals get old in captivity, much older than they would in the wild, and get cataracts, just like pet dogs do. Because of this, they have a whole tank at the rehabilitation centre just for blind seals! They are so cute!!

One of the blind seals at ecomare. Image: Alice Trevail

Anyway, that’s all for this post.

For more information about work on plastics and marine life by the Dutch group, IMARES, led by Jan Van Franeker, click here

For a great BBC Shared Planet podcast about plastics and fulmars featuring Jan Van Franeker as well as workshop attendees Lucy Quinn and Ewan Edwards, click here