Populations across the UK fell from around 12 million pairs in the 1970s to current levels of between six and seven million pairs, with greater reductions in rural and urban areas than in suburban Britain.
But the latest data from the British Trust for Ornithology (BTO) Garden BirdWatch, which monitors gardens across the country weekly, suggests declines recorded since the 1990s have levelled off.
The wildlife experts said there were a number of reasons for the decline - and for why it might have been stemmed.
Populations across Britain have been hit by a loss of nesting sites and food sources. In rural areas, changes in farming practices are thought to have affected house sparrows.
But in urban and suburban areas the causes have been more complex, possibly including greater competition with other birds.