The news that almost one in eight of the world's bird species are now threatened with extinction may not have come as a surprise. After all, since BirdLife International first published their magnum opus Threatened Birds of the World, back at the turn of the millennium, we have known that almost 1,200 species are at risk.

Now this number has increased to 1,227 species, with 192 classified as "critically endangered", a net rise of two species on last year and up from 182 in 2000. Once a species falls into this category the game is generally up – apart from a few well publicised success stories such as the Mauritius kestrel, once the world population of a species is numbered in dozens or hundreds, rather than thousands, it is usually doomed to a rapid extinction.

One bird added to the critical list has only just been discovered. The gorgeted puffleg joins the world's 350 or so species of hummingbirds, at least temporarily, before its Colombian montane habitat is destroyed so celebrities can sniff cocaine up their noses.

Other species are hanging on by such a slender threat that they are, to all intents and purposes, extinct. The list contains birds such as Bachman's warbler, ivory-billed woodpecker and Eskimo curlew, despite the fact that none of these North American species has been seen alive for many years. Things aren't much better on this side of the Atlantic: the slender-billed curlew hasn't been reliably sighted for a decade now, and appears to have gone the way of the great auk and dodo.

But it's the species in the "near threatened" category – which adds another few hundred to the list – which worry me most. Birds like the chimney swift of North America and the bateleur and martial eagles of Africa (both of which I saw on a recent visit there), have suffered such rapid falls in numbers that these once common and widespread species are suddenly under threat. Don't be surprised if familiar names like the cuckoo join them soon, if recent declines are anything to go by.

Of the 192 "critical" species I have seen just a handful: several species of vulture in India, the northern bald ibis in Morocco, the Balearic shearwater in Mallorca (and once, off Cornwall) and the sociable lapwing in Israel and, most memorably, Norfolk. Given the status of the others, I'm not likely to add to this total very soon.

BirdLife International's latest evaluation of the world's birds has revealed that more species than ever are threatened with extinction. A staggering 1,227 species (12%) are now classified as Globally Threatened but the good news is that when conservation action is put in place, species can be saved.

"In global terms, things continue to get worse – but there are some real conservation success stories this year to give us hope and point the way forward", said Dr Leon Bennun, BirdLife's Director of Science and Policy.

The rarest of the rare are growing in number

BirdLife International's annual Red List update, on behalf of the IUCN, now lists 192 species of bird as Critically Endangered, the highest threat category, a total of two more than in the 2008 update.

A recently discovered species from Colombia - Gorgeted Puffleg Eriocnemis isabellae - appears for the first time on the BirdLife/IUCN Red List, being listed as Critically Endangered. The puffleg, a flamboyantly coloured hummingbird, only has 1,200 hectares of habitat remaining in the cloud forests of the Pinche mountain range in south-west Colombia and 8% of this is being damaged every year to grow coca.

Sidamo Lark Heteromirafra sidamoensis from the Liben Plain of Ethiopia has also been uplisted to this category due to changes in land use, and is in danger of becoming mainland Africa’s first bird extinction. And coinciding with the 200th anniversary of Charles Darwin's birth, one of the Galapagos finches, Medium Tree-finch Camarhynchus pauper also becomes Critically Endangered, partly as a result of an introduced parasitic fly.

Common bird declines

But it's not only rare birds that are becoming rarer, common birds are becoming less common. In eastern North America, Chimney Swift Chaetura pelagica is fast disappearing from the skies. Following continent-wide declines of nearly 30% in the last decade alone, this common species has been uplisted to Near Threatened.

"Across Africa, widespread birds of prey are also disappearing at an alarming rate, and emblematic species such as Bateleur (Terathopius ecaudatus) and Martial Eagle (Polemaetus bellicosus) have been uplisted as a result. These declines are mirrored in many species, in every continent", said Jez Bird, BirdLife's Global Species Programme Officer.