Habitat is the key

A bird thought extinct for a century gets sighted and goes elusive again

In April 2005, biologists around the world were thrilled to learn that the Ivory Billed Woodpecker (Campephilus principalis) was sighted in the US. However, the excitement at the sighting of a bird once thought extinct was short-lived as some thought it was mistaken for the similar looking Pileated Woodpecker (Dryocopus pileatus). Every now and then there are reports of discovery and rediscovery of a species, right from a small plant to a huge mammal. What do these findings imply? One, there is much in this natural world waiting to be discovered. And two, there is always hope for species thought to be extinct.

But then, when do we conclude a species has gone extinct in the wild? It might be relatively easier to conclude a species has gone extinct in the wild or that it is locally extinct if the species is large bodied or conspicuous such as tiger or vulture, or if the species is unique to a region. But if the species is rare, nocturnal or if it is a small orchid which blooms once in several years in a rainforest, or a small deep sea fish, it will be difficult to pronounce it extinct even after several years of search.

If a species whose ecology, distribution, habitat or micro-habitat is well studied cannot be sighted after intensive search and its potentially suitable habitat has been completely wiped off, we could say it has gone extinct. But for how many species do we have such scientific information?

In this age of habitat destruction it’s natural to assume that certain species might have been wiped out. However, we must exercise caution in predictions about rare species. For example, the Jerdon’s Courser (Rhinoptilus bitorquatus) was thought to be extinct for more than 100 years until it was rediscovered in 1986 in Andhra Pradesh’s Cuddapah district; the place where the bird was rediscovered was immediately declared Sri Lankamaleswara Wildlife Sanctuary. Intensive research after 2000 resulted in locating the bird at three new places in the sanctuary, identifying and recording it’s call and mapping its broad habitat requirements.

The bird prefers scrub jungle with open areas with a particular density of bushes. It does not prefer a completely open area or a scrub with thickly-packed bushes. A study of the Jerdon’s Courser’s habitat requirement revealed most of its potentially suitable habitat was outside the sanctuary’s boundaries. Although the area in question is a protected one, cattle grazing and woodcutting are common. Overgrazing and rampant woodcutting will affect the bird’s habitat. But a moderate amount of these activities are likely to benefit the species since they will keep the habitat’s architecture intact.

Illustration: Karno GuhathakurtaSoon after the Jerdon’s Courser was rediscovered, the Andhra government planned an irrigation canal at the place it was found. Intervention of the forest department and several conservationists led to a change in the canal’s course. But another change in the canal’s course 20 years later destroyed one of the prime sites where the Jerdon’s Courser was discovered after 2000. Intervention by several conservation organisations and cooperation of the Andhra government again led to the canal’s realignment. But all is not well for the Jerdon’s Courser. The bird was sighted regularly till 2005 at the site of its discovery. However, check dams, percolation ponds and alien species in the open areas have disturbed its habitat. Use of sophisticated camera traps has not led to any sightings at this site.

Can we conclude the bird has disappeared from the area? American scientist Carl Sagan’s remark, “Absence of evidence is not evidence of absence”, is apt for the Jerdon’s Courser, at least in the Lankamaleswara Sanctuary. The area searched for the bird has been quite small. Vast tracts of scrub jungle in the region as well as in Andhra Pradesh remain to be surveyed.

As long as the bird’s habitat is intact, there is hope for it.