THEY were once among the most common birds to visit Scotland's gardens and hedgerows until their numbers began to fall dramatically in recent years.
And now birdwatchers and members of the public are being called on to held solve the mystery of the disappearing sparrow with a new project starting in Glasgow to find out where they nesting and how many are left.
Sparrow populations across the UK have been cut in half since the end of the 1970s from 12 million pairs to around seven million pairs today, with much of the decline taking place inside towns and cities.
Recent estimates show the number of the little brown birds in Glasgow may have fallen by as much as 90% since their heyday, and the race is now on to save the flocks that remain.
Volunteers are needed to count the sparrows in their area and to feed back information to researchers to help identify areas where the birds are thriving.
The project is being run by a team at Glasgow University in conjunction with RSPB Scotland, and will begin with a public meeting on April 1.
Toby Wilson, of RSPB Scotland said: "House sparrow numbers have been nose-diving across the UK in recent years, and Glasgow is following the trend.
"But parts of the city are still strongholds for these boisterous little birds, and we need help from the public to find them.
"Once we've got that information, we'll be able to use it to put up specialised nest boxes, and help people to give house sparrows a home near where they live."
The reason for the sparrows' decline is yet to be established, although it is thought that it could be linked to disappearing habitat, especially in urban areas.
In rural areas, changes in farming practices are thought to have affected the birds, but in towns and cities causes such as cats, air pollution and pesticides have been said to be behind the decline.
However, it is more likely that sparrows, which need large, unkempt green spaces to thrive, are affected by modern tastes for manicured gardens and landscaping and the destruction of overgrown verges and embankments.
Dr Ross McLeod of Glasgow University, who was involved in the research said: "House sparrows are one of those birds that most people will recognise, and they're easy to identify.
"They have relatively short wings compared to their weight and so like to stay close to cover so that they can escape quickly if threatened.
"They seem to be flourishing in areas with bushy vegetation and plentiful food, but we're in need of more sightings from the public to be able to confirm our current findings."
Volunteer surveyors will be asked to set aside a morning every couple of months to look for and record house sparrows near where they live.
No specialist knowledge is needed, and volunteers can take on as large or as small an area as they wish. They are urged to sign up for the project at the April meeting at the RSPB Scotland office near Charing Cross.
The project is expected to run for two years and counts will be taken in winter and during the breeding season.