6 December 1996 'Messenger of the morn' a bio-indicator for science

The "happy skylark springing up to the broad, blue sky" is making a major contribution to a benchmarking agricultural sustainability study in New Zealand at Leeston, near the South Island's largest city, Christchurch.

"Birdlife levels are always a potent indicator of environmental health," says researcher Professor Steve Wratten of Lincoln University's Department of Entomology and Animal Ecology.

"For example, in Britain in recent years an estimated 10 million pairs of skylarks have disappeared as a result of environmentally damaging agricultural practices.

"Here in New Zealand we're including skylarks among the bio-indicators in our work with the Selwyn Stewardship Monitoring Scheme and already interesting patterns have shown up in the 12-paddock, three farm types study.

"It's too early to attach precise meaning to what we have observed but a greater concentration of the birds has shown up on some of the sheep and beef paddocks in contrast to the arable farm land."

Professor Wratten and the Lincoln scientists will be monitoring the skylarks of Selwyn over a period of four years and they will be looking at areas such as population densities on the various types of paddocks, food availability, diet (through an analysis of faecal material analysed for invertebrate fragments) and the presence of chemical residues (through blood analysis).

The birds' use of paddocks will be related to current and past cropping type and agricultural chemical use and compared within and between farms.

Lincoln University's Plant Protection Research Unit is providing baseline data on pesticide levels in the study paddocks.

It is the first time a bird species has been used as a bio-indicator in this scale of study in New Zealand.

Ian Collins, Journalist, Lincoln University, Canterbury, New Zealand.