Monday, 28 May 2012

Counting in a minefield

This weekend I have mostly been counting gulls' eggs. 

My daughter and I joined a team of volunteers who go out to the Isle of May each year to find and count the thousands of herring and lesser black-backed gulls' nests on the island. The process was strangely reminiscent of a military minesweeping operation. The eight of us lined up across a mapped and marked section of the island, clip boards and spray cans poised expectantly, while our leader briefed us on our tactics - cane in hand, pointing forwards, for all the world like a battle commander urging his troops into battle.

The tactics are as follows: walk forward, keeping in line, about 10ft from your neighbour, looking for gulls' nests. If you spot one mark it with the spray can and write down the number of eggs it contains. Move on. Simple. Simple, but complicated by a couple of details. While you are walking forward you are subjected to a continual bombardment by screeching, angry gulls. The gulls rarely actually strike people, but they fight a dirty war, and some of us came back decorated with very smelly battle scars. To add to the tension, the gulls nest in the same areas as the puffins, and the ground is riddled with their burrows. Put your foot through one and you risk blocking the tunnel to the nest chamber, meaning an egg or chick can be trapped inside - a death sentence. We walked as if through a minefield, trying to keep to the tussocks of vegetation and rocky outcrops. Inevitably there were a few implosions, but these were immediately rebuilt with turf and slates brought along for the purpose, and luckily there were no casualties. 

Thankfully the gulls' nests are relatively easy to spot. Perfect, round bowls of pale, dried grasses, with between one and four coffee-coloured, dark-speckled eggs huddled inside. They are surprisingly small for such impressive birds, and are hidden completely when a parent is incubating, so that the adults look like fat ladies perching on tiny stools.

But despite the risks the count has to go on. It's important to know how many gulls are on the island, and whether their numbers are stable or increasing. All the gulls are protected species, one of the reasons the island is part of the Forth Islands Special Protection Area, and it's important that we know how well they are doing here. The herring gull is the classic ‘seagull’ that we all imagine when we think of the seaside, with its silvery-grey back and keen, yellow eyes. Its close cousin, the lesser black-backed gull, stands out with its sooty-black wings and yellow legs. They breed on the island in mixed, loose, raucous colonies.

These closely-related gulls are relative newcomers to the island. They only began to breed here in the first half of the 20thcentury. But by 1970 their numbers had swelled to 17,000 – possibly as a result of the easy pickings to be had at rubbish tips on the Fife mainland, and the discards from fishing vessels. There was concern that this population explosion would damage the fragile ecological balance on the Isle of May, as the gulls can prey on other protected seabird species such as puffins and terns. And so conservationists made the difficult decision to cull their numbers to protect the other, more sensitive seabird populations on the island. During the 1970s and early 1980s over 40,000 gulls were removed. Happily this seemed to restore the balance, and in 1986 the cull was ended. Now gull numbers seem to remain stable at around 3000 pairs each year, and they are an intergral part of the island's ecology.

Managing species can be a minefield too - look at the furore inspired by removing hedgehogs from the Hebrides, or by culling red deer. Some suggest we should just 'let nature take its course'. What I think they forget is that it is almost always human intervention or influence that got things out of balance in the first place - top predators removed, wildlife introduced inappropriately, or, as in the case of the gulls, opportunistic species' populations becoming artificially high and threatening more specialist species. 

But however unpalateable it may be, there's really no going back, no reneging on our responsibilities now things are getting awkward. We got the natural world into this mess, and its up to us to try to get us out of it.

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