SCIENTISTS trying to find the cause for the massive decline in the population of the humble house sparrow - millions of the birds have simply disappeared - have narrowed their research to three possible danger areas:
The loss of nest sites through new forms of roof insulation and the use of PVC barge-boards? The Increasing numbers of cats and sparrow hawks? Or high levels of traffic?
The sudden decline in sparrow numbers took naturalists by surprise when it was first logged in the late 1990s. The bird had always been considered one of the hardiest species in the UK, a cheeky, chirpy character able to scratch a living even in the most run-down urban areas.
Then, suddenly, some 10 million and perhaps more were missing and scientists from the Royal Society for the Protection of Birds and the British Trust for Ornithology launched a joint investigation to find the cause.
First results show that food shortage may be one reason: sparrows thrive better when they are fed by humans. The three other alternatives are now under intense study.