The population of house sparrows in Britain has fallen by 68% in the past three decades, according to the RSPB.
A report by the charity said the paving over of front gardens and removal of trees had caused a big decline in insects which the birds eat.
It suggests that sparrows are now disappearing altogether from cities such as London, Bristol and Edinburgh, the BBC News website reports.
Dr Will Peach, from the RSPB, said many gardens had become “no-go areas for once-common British birds”.
They studied numbers in Leicester over a three-year period and found that they fell by nearly a third.
Dr Peach said every pair of house sparrows must raise at least five chicks a year to maintain the population, but many were starving to death in their nests or were too weak to live long after fledging.
The study did find that chick survival was higher in areas where insects, such as aphids, were more abundant.
Dr Peach said: “Peanuts and seeds are great for birds for most of the year, but sparrows need insects in summer – and lots of them – to feed their hungry young.
“Honeysuckle, wild roses, hawthorn or fruit trees are perfect for insects and therefore house sparrows.
“The trend towards paving of front gardens and laying decking in the back, and the popularity of ornamental plants from other parts of the world, has made many gardens no-go areas for once common British birds.”
He said gardeners could help sparrows by “being lazy, doing nothing and allowing the garden to be a little bit scruffy”.
The study, published in the journal Animal Conservation, concluded that the decline in house sparrows in Britain began in the mid-1980s.
In London, numbers fell by 60% between 1994 and 2004.
The house sparrow has been added to the list of species identified by the UK Biodiversity Action Plan as in need of greater protection.
Source: BBC News website