Co-ordinator Richard Bashford told BBC Radio 4's Today programme "a lack of food for the chicks" was causing the fall in the number of housesparrow sightings.
The Royal Society for the Protection of Birds (RSPB) said that as well as the housesparrow, the starling was another familiar garden bird to feature on the BAP list of 59 bird species.
WHEN, a few years ago, word came that British bird lovers anxious about the decline of the housesparrow had appointed a sparrow tsar, it seemed that the tsar vogue must have reached its zenith.
Dr Garamszegi's work, published in Global Change Biology, found that the housesparrow (Passer domesticus) showed a malaria prevalence that was less than 10% before 1990 when worldwide temperatures were cooler, but in recent years nearly 30% were infected.