London, September 22 : A global assessment has warned that the populations of the world's common birds are declining as a result of continued habitat loss.
According to a BBC News report, the survey by BirdLife International found that 45 percent of Europe's common birds had seen numbers fall, as had more than 80 percent of Australia's wading species.
The study's authors said that governments were failing to fund their promises to halt biodiversity loss by 2010.
The State of the World's Birds 2008 report, the first update since 2004, found that common species - ones considered to be familiar in people's everyday lives - were declining in all parts of the world.
In Europe, an analysis of 124 species over a 26-year period revealed that 56 species had declined in 20 countries.
Farmland birds were worst affected, with the number of European turtle-doves (Streptopelia turtur) falling by 79 percent.
In Africa, birds of prey were experiencing "widespread decline" outside of protected areas. While in Asia, 62 percent of the continent's migratory water bird species were "declining or already extinct".
"For decades, people have been focusing their efforts on threatened birds," explained lead editor Ali Stattersfield, BirdLife International's head of science.
By consolidating data from various surveys, the team of researchers were able to identify trends affecting species around the world.
While well-known reasons, such as land-use changes and the intensive farming, were causes, Stattersfield said that it was difficult to point the finger of blame at just one activity.
"The reasons are very complex. For example, there have been reported declines of migratory species - particularly those on long-distance migrations between Europe and Africa," she said.
"It is not just about understanding what is happening at breeding grounds, but also what is happening at the birds' wintering sites," she added.
She said that the findings highlighted the need to tackle conservation in a number of different ways.
"It is not enough to be looking at individual species or individual sites; we need to be looking at some of the policies and practices that affect our wider landscapes," said Stattersfield.
One-in-eight of the world's birds - 1,226 species - was listed as being threatened. Of these, 190 faced an imminent risk of extinction.
The white-rumped vulture, a once common sight in India, has seen its population crash by 99.9 percent in recent years.
An anti-inflammatory drug for cattle, called diclofenac, has been blamed for poisoning the birds, which eat the carcasses of the dead livestock.
According to Stattersfield, the basis for the decline is well understood and measures are being taken to remove diclofenac from veterinary use in India.