London, March 1 : Prey species may be a better overall indictor of the ecosystem's health, according to an analysis.
Tobias Roth and Darius Weber at the Swiss Biodiversity Monitoring Programme in Basel, analysed data on plant, bird and butterfly species richness from across Switzerland.
They compared the richness of sites where birds of prey had been spotted and that of areas where such birds were absent.
The researchers observed that areas where raptors were absent had lower species richness.
Thereafter, the researchers extended their analysis to a common prey species-tits.
Tit and raptor species were equally good indicators of bird and plant richness, they said.
However, tit species were twice as likely to function as good indicators of butterfly richness, probably because butterflies and tits live in similar habitats-above the densely populated valleys and below the cooler peaks, so one indicates the presence of the other.
"It is our strong feeling that biologists have underestimated ecosystem health by relying on top predators alone," New Scientist quoted Roth as saying.
The researcher, however, clarified that he did not want ecologists to abandon monitoring predator populations, and start studying prey species alone.
"Raptors, birds, butterflies, and snails, all show a different part of the ecological picture, we need to look at all of them to really understand what we are seeing," says Roth.
A paper describing the analysis has been reported in the Journal of Applied Ecology.