Missing numbers

No credible census

The ambiguity over the peafowl's status is symptomatic of a serious problem there is no formal nationwide survey to count birds like the Common Bird Census in the uk and the Breeding Bird Census in the us. Accounts of decline in bird numbers are mostly impressionistic. Of course, there are population estimates of some flagship species. But these are based on individual research studies which are usually region-specific. Some organisations like bnhs do conduct bird census in collaboration with international groups. Some of them, like the Asian Waterfowl Census (awc), enjoy a fair degree of credibility among professional and amateur birdwatchers. But similar programmes for terrestrial birds have not taken off.

In February this year, the forest department in Coimbatore did embark on a census along these lines.The two-day exercise involved amateur birdwatchers, botanists and wildlife photographers along with department personnel. But their objective was to prepare a checklist of birds rather than count the numbers of individuals of a species. Counts such as these end up being an inventory and do not detail how many individuals of a species survive. This is critical to know how many birds are threatened and the extent of the threat.

A review article by A J Urfi and his colleagues from the University of Delhi (Current Science, Vol 89, No 12, December 2005) notes that though there is general awareness of counting techniques, population estimates provided by most surveys are not reliable. "Population estimation exercises have been undertaken for a variety of endangered birds such as the Siberian crane (Grus leucogeranus), sarus crane, great Indian bustard, lesser florican (Sypheotides indica), Bengal florican (Houbaropsis bengalensis), narcondam hornbills and vultures. But some of these studies have not employed rigorous field methods," the paper says. There is more than a grain of truth in this contention. Surveys have rarely gone beyond impressionistic methods. For example, a 1998 survey to count water fowl in Keoladeo Ghana National Park claimed to use the 'total count' method. Actually what happened was that the surveyors went about counting birds around certain vantage points such as untarred roads and dykes. Similarly, another survey in Nanda Devi National Park, Uttaranchal, used the 'encounter rate and call index'--birds were counted when they were sighted.

The pioneers
The first large-scale bird census in the country was undertaken in 1987, initiated by the Asian Wetland Bureau (now known as Wetland International) and bnhs. A large number of amateur birdwatchers were involved in the census--known as awc. The idea, says Ashok Varma of the Wildlife Institute of India, Dehradun, was to contribute to knowledge about the ecology of bird species and populations, document the human impact on bird populationsand identify critical and important areas for conservation.However, some experts say that awc has not developed a rigorous methodology, and bird counts in most cases have ignored standard protocol. Verma disputes this. "awc, at least, gives a sense of where we are heading to in terms of wetland status and water bird population", he says. But there seem to be identifiable problems. The number of sites covered has come down 529 in 2003, through 423 in 2004 to 139 in 2005.

Going amiss

The lack of a nationwide census means that we do not have data on the national bird, or even common birds like the house sparrow (see box Where have all the sparrows gone?).
The disappearance of the house sparrow especially from urban areas is not something new, but so far there has been no response in India unlike the uk," says Ashish Pittie, editor of the journal Indian Birds.

Quite a few alarm bells rang in Europe when the population of sparrows declined drastically--by up to 85 per cent-- in London. The disappearance of sparrows in India has also been widely reported in the media, though reliable information on the sparrow population is still scarce. There is similar confusion over the status of another bird, the Indian shag (Phalacrocorax fuscicollis). It's usually deemed as a common bird. But only 627 individuals were counted during the 2005 awc from nine states.

"A dominant trend of bird-count exercises undertaken in India has been a focus on endangered birds, wetland birds, heronries and birds found in terrestrial habitats significant for conservation," claims the article by Urfi and his colleagues. "While the emphasis on endangered birds and high-value habitats is understandable, and also justified on account of their conservation significance, census of common birds has generally been ignored," the paper notes.

Ecological loss
The failure to come up with credible bird counts has ecological ramifications. The loss of birds doesn't merely mean that our gardens are less redolent. Beyond aesthetics, birds perform crucial environmental services. Ecologists say that a region with a rich diversity of birds will also have a relatively high diversity of trees, shrubs, mammals, reptiles, frogs and invertebrates. This is why birds are recognised as 'indicator species' their presence indicates environmental health of an area. All the bustard species (great Indian bustard, lesser florican and Bengal florican) are indicators of the health of grassland ecosystems of Indian plains. The three species forage, shelter, display and breed in grasslands and their absence is the first warning signal that the grasslands are in peril.

"Birds also perform critical environmental services," says Ravi Shankaran of sacon. They are voracious eaters of weeds and farm rodents, they help keep insect populations under control, and pollinate and disseminate seeds. "So, extinction of bird species or their declining numbers disrupt ecosystem processes," says Shankaran.

For example, in many parts of the country, the decline of vultures has been accompanied by a rise in the numbers of carrion-eaters such as rats and feral dogs--animals that are reservoirs for diseases.

Another good example is the Keoladeo Ghana National Park. Rodents have, of late, become a scourge for residents of villages around the park, damaging crops. Experts such as Varma attribute the scourge to the decline in the numbers of birds of prey like the harrier.