SEVERAL BIRD SPECIES THAT MAKE ANNUAL MIGRATIONS BETWEEN AFRICA AND EUROPE HAVE EXPERIENCED DRASTIC POPULATION DECLINES AND SCIENTISTS ARE NOT EXACTLY SURE WHY, CONSERVATIONISTS SAID ON FRIDAY, ACCORDING TO REUTERS. THE FINDINGS WERE REVEALED IN A STUDY BY THE BRITAIN-BASED ROYAL SOCIETY FOR THE PROTECTION OF BIRDS (RSPB) AND BIRDLIFE INTERNATIONAL. "SCIENTISTS FEAR THAT THEIR DWINDLING NUMBERS -- WELL OVER 50 PER CENT DOWN IN SOME CASES -- MAY BE A WARNING OF WIDESPREAD ENVIRONMENTAL DAMAGE, WHICH COULD SOON AFFECT MAN AS WELL," THE RSPB SAID IN A STATEMENT. "CLIMATE CHANGE, DROUGHT AND DESERTIFICATION IN AFRICA, AND MASSIVE PESTICIDE USE ON AFRICAN FARMLAND MAY ALL BE TO BLAME FOR THE DECLINES OF ONCE COMMON UK BIRDS SUCH AS THE SPOTTED FLYCATCHER, WHEATEAR, WOOD WARBLER AND TURTLE DOVE," IT SAID. RESEARCHERS WERE LOOKING AT FACTORS SUCH AS DROUGHT AND HEAVY PESTICIDE USE IN THE SAHEL REGION OF AFRICA, WHICH BORDERS THE SAHARA DESERT AND IS A MAJOR STOPOVER POINT FOR BIRDS THAT HAVE MADE THE EXHAUSTING JOURNEY ACROSS THE UNFORGIVING SANDS. THE RSPB SAID THE RESEARCH, TO BE PUBLISHED IN THE JOURNAL "BIOLOGICAL CONSERVATION", SHOWED THAT 54 PERCENT OF THE 121 LONG-DISTANCE MIGRANTS STUDIED HAVE DECLINED OR BECOME EXTINCT IN MANY PARTS OF EUROPE SINCE 1970. THE RSPB SAID SPECIES SUCH AS THE RED-BACKED SHRIKE NO LONGER BREED IN BRITAIN, WHILE THE SPOTTED FLYCATCHER'S NUMBERS WERE DOWN 86 PERCENT IN THE UNITED KINGDOM. "THESE MIGRANTS ARE HIGHLY EVOLVED AND SOME RANGE OVER A QUARTER OF THE PLANET'S LAND SURFACE. FOR SPECIES LIKE THIS TO BE AFFECTED SO SEVERELY SUGGESTS THAT SOMETHING PRETTY SERIOUS IS GOING WRONG SOMEWHERE," SAID THE RSPB'S DR PAUL DONALD, A CO-AUTHOR OF THE STUDY.