This column is normally in favour of keeping birds alive, but just for a change, let’s celebrate killing them. The house crow has just been eradicated from the Socotra archipelago in Yemen — hurrah! No more crows; all gone, defunct, wiped out. Hurray for all those dead birds!

It’s all the fault of an officer of the Bombay Infantry who, for reasons best known to himself, decided to release a few house crows in Aden. Perhaps he liked them. Perhaps he just fancied being God. These crows are naturally found in southern Asia, but they have been spread by the hand of man. The Aden birds became hardened ship travellers, have hitched lifts all over the place, and thrived once they got there.

They reached Socotra in 1996, and started eating their way though the extraordinary creatures that have developed on the archipelago, and which are found nowhere else in the world. There are 18 species of gecko found here, of which 15 are found nowhere else. There is a tiny species of shrew, reckoned by some to to be the world’s smallest mammal. There are 192 species of birds, and six of these are endemics: the Socotra sparrow, sunbird, warbler, starling, cisticola and bunting.

These hotspots of biodiversity, these cauldrons of evolution, are among the world’s treasures. The creatures evolved for a place that has since been violently tweaked by human clumsiness. As a result, the strength of their precise adaptation becomes a source of fragility.

The house crow population reached ten pairs; enough to constitute a significant threat to the Socotra specials. Attempts to trap them consistently failed; crows are smart. So the Socotra Archipelago Conservation and Development Programme, backed by Birdlife International, came up with a brainwave: get the children to do it. They offered a reward to any child bringing in a crow’s nest full of young. It worked and the last few birds have just been shot.

The Socotra specials can carry on living their unique and isolated lives. A small bit of damage has been undone. A small reverse for a crow: a great leap forward for the Socotra cisticola.

Illegal aliens

Invasive species: one of the great conservation problems, one that frequently poses difficult questions. A conservationist must sometimes take the hard-nosed view that a damaging invader must be eradicated. Some are more gung-ho about this than others. Sometimes it can become a righteous crusade; at other times a form of xenophobia.

Some invaders do great damage, others rather less. The introduction of grey squirrels into this country is a classic disaster: the squirrel-pox virus they carry but don’t die from kills the reds. As a result, the reds have been pushed back to the edges of their former range.

All the mammals in New Zealand, apart from bats, are invaders. Some, such as rats, were carried in accidentally on ships, others, such as foxes, were introduced for the fun of it. Before people arrived, New Zealand was a nation of birds; unique, bizarre, many flightless, some enormous. Most of them are now gone.

Across the world, domestic cats are an introduced and frequently well-fed predator. Cats will kill for food or for sport, and have affected populations of small mammals and birds across the world. The hedgehogs introduced to the island of Uist munched their way through the tern’s eggs.

Invasive plants also cause havoc: African grass across South America, or for that matter (since I am writing these words in Wales) rhododendrons on Snowdon: a moment’s carelessness and an entire ecosystem is changed. But some invaders do little apparent harm: I have never heard a single voice raised against the little owl, a charming creature introduced into this country in the 19th century.

Accidents will happen, but we are too civilised, too careful these days to introduce alien creatures for purely frivolous reasons. And in this country, where we are highly conservation-aware, surely the time for deliberate introduction of alien species is long past.

Not so. There is an Asian bird that we bring to this country every year, and do so in vast numbers. Some put the annual invasion as high as 30 million. They can be seen all over the countryside, and they will eat practically anything. They have a particular relish for reptiles, which is poor news for lizards and slowworms. These birds are introduced purely for fun. They are called pheasants.

Golden duck?

I am writing these words in the press-box at the Swalec Stadium in Cardiff, where I am covering the Test match for this newspaper. I can reveal that the first bird of the Ashes was a cormorant. Gulls are always about here, mainly lesser-black-backed and herring. It’s a nice walk from the station to the ground, too, along the River Taff. You can hear the sweet chirrup of grey wagtails as you go. I saw a just-fledged family on the far bank, leaping and dancing — Italians call them ballerinas — in a blaze of yellow. They’re not actually all that grey — and they’re a much more cheering sight than a Ricky Ponting century.

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