How Oil Spills From Wartime Sea Battles Nearly Wiped Out Famous Welsh Guillemots

Andrew Astbury / shutterstock

Danielle Andrew 08 Nov 2016, 11:06

The ConversationThe sight of an oiled seabird is mercifully rare these days. I cannot imagine a more appalling way to die.

The guillemot, a small penguin-like (but flighted) seabird, is especially vulnerable to oil and, over the past century, hundreds of thousands – possibly millions – have perished as a result of ships flushing out their bilges, tankers breaking up, or ships sinking.

In a new study, I have shown that oil pollution caused a 95% reduction in the guillemot population of Skomer Island in Wales – and probably much of the rest of southern and western Britain.

Skomer, a tiny speck of land just off the rugged Pembrokeshire coast, is surrounded by high cliffs which keep foxes and rats away and have turned the island into a world-renowned seabird paradise.

High cliffs and strong currents keep the predators away. Tim Birkhead, Author provided

I have studied the island’s guillemots each year since 1972, and over that time have built up a good understanding of how their population works (how long they live, the age at which they first start to breed, their reproductive output and so on). Colleagues and I collect this data partly for academic research but also because annual documentation of such population measures is an essential part of monitoring – that is, keeping an careful eye on how the population is doing. High quality monitoring is our only ammunition against those forces that are driving much of our wildlife towards extinction.

My study began as a PhD. Guillemot (and other seabird) numbers were in decline, in part because of the 1967 Torrey Canyon oil tanker disaster, followed two years later by a mysterious mass die-off of guillemots thought to have been due to toxic chemicals. When I started in 1972 there were just 3,500 individual guillemots on Skomer. The aim of my PhD was to try to understand their population dynamics. A three-year PhD was too short however, for a bird that can live up to 40 years, so I continued – and have done so ever since.

By the mid 1980s, to my surprise and delight, the population started to increase – and it has continued to do so at a rate of about 5% per annum ever since, and numbers on Skomer now stand at 25,000 birds.

Guillemot counting on Skomer Island. Tim Birkhead, Author provided

One would imagine that this increase would have been viewed very positively, but in 2014 the Welsh government used it as an excuse to terminate the modest (but adequate) funding that it had indirectly provided for the previous 25 years. The argument was that if the population was increasing there was nothing to worry about – that is, they saw no value in long-term high quality monitoring. So far I have managed to keep the study going by crowd funding, but that will run out in two years.

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