Nature Studies by Michael McCarthy: Rarity has a value all of its own

Why is rarity so prized? What deep psychological roots in us does it tap? It clearly has nothing to do with the inherent properties of a given object, as a tatty and overprinted postage stamp will have immense allure for stamp collectors, if very rare, whereas a clean and exceptionally beautiful stamp which has just been issued in its millions will carry no cachet.

Rarity seems to bestow its own glamour and value. Perhaps its resonance comes from our tribal past and is linked with exclusivity – rare objects were exclusively the property of the most powerful individuals. It certainly conveys its own fascination, and experiments have shown that people will look upon commonplace objects or creatures quite differently if they are told that they are exceptionally scarce. Which is why stories about rare fauna and flora are good stories – I know, having written scores of them myself – and why accounts of the rarest are the best stories of all. The story of the last Spix's macaw, for instance, the pale blue parrot from northern Brazil which for 10 years was represented in the wild by one lone remaining individual, went round the world. But the story of the ivory bill is in a class of itself.

Maybe you have to be an American to feel the force of the legend of the ivory-billed woodpecker, sometimes known as the Lord God bird from the awed exclamations of people who caught sight of it in the dense forests of the southern states where it lived: a whacking great vision of black, white and scarlet, bigger than a crow. As its forests were chopped down in the late 19th and early 20th centuries the ivory bill got scarcer and scarcer, until in the 1940s it disappeared altogether: the last accepted record was in 1948. Since then it has been presumed extinct. But not by everybody.

Over the past half century numerous enigmatic and furtive glimpses have been reported, never backed up by incontrovertible evidence, but enough to persuade a substantial body of American birders and ornithologists that the Lord God bird is Out There. This came to a head in 2004 and 2005 when the most dynamic bird study centre in the world, the Cornell Laboratory of Ornithology (at Cornell University in Ithaca, New York State) mounted an ambitious expedition to find the ivory bill in a remote part of Arkansas, and eventually announced it had succeeded.

Cue natural history sensation. It made front pages around the globe. The Cornell Lab director, John Fitzpatrick, and his team claimed to have made several sightings of a male ivory bill and produced a blurred video of what looked like a large black and white woodpecker flying away. Wonderful! But doubts set in, especially after America's leading bird artist, David Sibley, reanalysed the video with several academic colleagues and said it could perfectly well have been of the not dissimilar pileated woodpecker. Since then, ivory bill controversy has gripped the ornithological world in the US, with people taking sides and passions running high. I've met one of the ornithologists on the Arkansas expedition, who told me of her own sighting (I was riveted). She said: "I've been treated as a fantasist, and I've been treated like a rock star, but I know what I saw."

The ivory bill now represents the Holy Grail of American ornithology, perhaps of ornithology anywhere, such is our fascination with rarity. But even if it does still exist, it may not be the rarest bird in the world. That distinction may belong to the po'ouli, a Hawaian honeycreeper not seen since 2004, or the slender-billed curlew, not definitely seen since 2001, or perhaps the eskimo curlew, not seen since 1981, or Australia's night parrot, refound in 2006. The stories of these species. and of a few dozen more which are teetering on the brink of extinction, or may indeed have toppled over, are told at length in two books which have just appeared virtually simultaneously: Facing Extinction: The World's Rarest Birds And The Race To Save Them by Paul Donald, Nigel Collar, Stuart Marsden and Deborah Pain, and the Atlas Of Rare Birds by Dominic Couzens.

They're quite different in approach: the first is virtually an academic treatise by four ornithological scientists, although immensely accessible to the general reader and beautifully illustrated; the second is squarely aimed at a popular audience but authoritatively written by one of our best writers on birds, with fascinating maps. The two complement each other beautifully (although that can hardly have been the intention of either publisher), and you would do well to buy them both – if you've just been paid, or had a small lottery win, as the pair will set you back a penny short of seventy quid.

But open either one and you'll enter into that enigma, rarity, which casts its inescapable spell over the human mind when reverberating around stamps, or coins, or wines, or books, but to some of us is even more effective when enveloping our fellow creatures, especially ones so singular they prompt the naming of the Lord.

Happier news for the red-backed shrike

To speak of a rare British bird: last week in The Independent I reported on the happy return of the red-backed shrike after a long absence. I mentioned it had been away from England for 18 years, but also said it had been absent from Britain as a whole during that time. Not so: it has bred several times in Scotland and Wales since 1992. I am happy to put the record straight.

For further reading

'Facing Extinction: The World's Rarest Birds And The Race To Save Them', by Paul Donald, Nigel Collar, Stuart Marsden and Deborah Pain, (T & AD Poyser, 2010); 'Atlas Of Rare Birds', by Dominic Couzens (New Holland, 2010)