Up to 100 million UK birds are crashing into windows each year, with a third of them dying, a bird research group says.
Window strike threatens many birds, the BTO thinks
The British Trust for Ornithology (BTO) says that some birds which are important for conservation are at particular risk.
It is going to carry out a survey to study the effects on bird populations and explore ways to reduce fatalities.
One proposal is to put stickers shaped like birds of prey in garden windows to try to prevent the lethal collisions by scaring the birds away from danger.
Mike Toms, who is co-ordinating the BTO survey, says: "This is a staggering number of birds being lost each year and many are of species that we know are already in trouble.
Many vulnerable species
"We are particularly interested in reports of song thrushes flying into windows because this is a declining species and one for which gardens are particularly important."
Eleven thousand ringed birds are reported each year to the BTO, half of which are found dead.
With sparrowhawks, it says, where the cause of death is known, over a third had been killed by window collisions.
Songthrushes are especially vulnerable, (image: Rob Nottage/BTO)
House sparrows, robins, chaffinches, blackbirds, and greenfinches are all reported to die in this way.
The BTO acknowledges these are tentative figures extrapolated from a small number of records.
It wants to test the effect of putting up window stickers, known as sentinels, designed to deter birds from crashing into the glass.
The sentinels look like a bird of prey or a spider-web, and people who use them say they do help to prevent window strikes.
Penalty of human contact
The BTO says: "Gardens are great places for birds, especially ones in which food and nesting are provided.
"However, there are costs associated with living alongside man, one of which is the risk of colliding with glass windows."
Mr Toms told BBC News Online: "Three major causes of bird deaths are cats, collisions with cars, and collisions with garden windows.
"Song thrushes have seen their population drop by about a half since the 1970s.
"This is a species which is primarily based in the gardens, so any factor that operates in the gardens could be the one causing a decline."
The study will run from April until August this year, and the BTO is looking for volunteers.