Worries take wing

Based on the analysis of the conservation status, distribution and life histories of 9,787 extant and 129 extinct bird species, the researchers predict that 6-14 per cent of all bird species will soon be extinct, 13-52 per cent will be functionally deficient and 7-25 per cent will be functionally extinct. The latter figure would be as high as 28-56 per cent on oceanic islands. The global number of birds is already believed to have plummeted by 20-25 per cent.

While the ecological roles of birds often perish with distinct ecosystems such as forests or wetlands, experts say that half of the threatened species are imperilled by factors besides habitat loss like exploitation, introduced species, pathogens, fragmentation. This is particularly pronounced in the case of scavengers (100 per cent), piscivores (80 per cent), herbivores (78 per cent), omnivores (76 per cent), granivores (56 per cent), frugivores (53 per cent) and birds weighing less than 100 grams (73 per cent).

Frugivores, herbivores (both disperse seeds), nectarivores (pollinate plants), piscivores (predate on fishes and invertebrates and produce guano) and scavengers (consume carrion and check diseases) would disappear at greater-than-average rates, some by as much as 46 per cent. Forest, marine and wetland habitat and regions with large numbers of island birds will suffer the worst. And since specialised (such as tropical insectivores that rein in pests) and evolutionarily unique species run greater risk of extinction, nature may not be able to compensate for their loss.

In South Asia, say the experts, the rapid dip in vulture population, virulent diseases and high human population density would unleash more instances of bubonic plague, anthrax and rabies. ‘‘In 1997, over 30,000 of the world’s 35,000-50,000 rabies deaths took place in India, where feral dog and rat populations have exploded after the decline of vultures,’’ they say. Investments in arresting the drop in plumed populations will pay off only while there is time to act. Sadly, we are fast running out of that too.