‘We shot a new pigeon’
- Extinct Birds by Errol Fuller
Oxford, 398 pp, £29.50, May 2001, ISBN 0 19 850837 9
In October 2000, the last wild Spix’s macaw, a solitary male, disappeared from its patch of forest in Brazil. The species is not, technically, extinct: a few dozen individual birds survive in zoos and in the aviaries of private collectors, but it is now in the realm of the undead, where it will remain until either the last individual dies or – less likely – the species is resurrected in a successful reintroduction to the wild. In a hundred years’ time, it will almost certainly join the entries in a much larger edition of Extinct Birds. Errol Fuller’s book recounts the story of the eighty or so bird species known to have been extinguished during recorded history, in every case by human beings or their proxies – rats, cats, dogs, pigs and other introduced animals, plants and microbes. At current rates, the 2101 edition will run to 15 volumes – and what has happened to birds provides a good yardstick for estimating the chances of other organisms. Because they are conspicuous, their extinction is better documented than that of most other creatures. We can be reasonably confident that nearly all the bird species that have survived until the 21st century have been described and classified, something that can’t be claimed for any other animal group (except perhaps mammals).
Parrots like Spix’s are peculiarly vulnerable to extinction. At least 12 species have vanished, and another fifty are officially endangered and likely to become extinct in the next few years or decades without – or even despite – the intervention of conservationists. These birds have been let down either by their attractive plumage or their loquacity, condemned to be turned into hat decorations or to life in an aviary. Like orchids (the parrots of the plant world), many parrot species have small, geographically restricted populations and are fussily slow about reproduction – a lethal combination.
Lack of exposure to serious predators over evolutionary time – because they lived on tropical or subtropical oceanic islands – was the downfall of most of Fuller’s birds, and threatens many more. The absence of predators meant that they failed to develop escape behaviours. Some are also flightless, a characteristic which tends to evolve in the absence of ground-dwelling competitors (rodents, for instance, are generally absent from the native fauna of Pacific islands). Other behavioural peculiarities, too, become frailties when population size is reduced, and threaten to tip a species over the brink. The kakapo, a four-kilo ground-dwelling New Zealand parrot whose deep, booming mating call (which can be heard at http://www.bigjude.com/Page8.html) was compared by the late Douglas Adams to the opening bars of a Pink Floyd album, is unique among parrots in having a mating system in which females choose between males gathered together on a common display ground. Now that only fifty wild individuals are left in scattered locations in New Zealand, male displays are often solitary, and females may simply not manage to locate prospective mates. The Mauritius kestrel was probably the rarest bird of prey in the world in the 1970s. This was because of its diet: it lived exclusively on geckos, which were becoming scarce because of the destruction of their island habitat. Parent birds taught their offspring to hunt only geckos, despite the availability of other prey. Conservationists running captive breeding programmes found that baby kestrels were not so fussy, and could be trained to catch a variety of prey. Released from monophagy, the birds have won a reprieve of sorts.