Half a million birds from 60 species were spotted across Wales during this year's Big Garden Birdwatch, organised by the RSPB.
The house sparrow may be short of places to nest
And more than 25,000 people in Wales - almost 10,000 more than last year - took part in the annual survey.
But while numbers taking part were up, the results show a marked decline in some garden birds.
Although the house sparrow retained top spot, its numbers were significantly down from the first birdwatch in 1979.
Birdwatchers across Wales flocked to their gardens and local parks for the Big Garden Birdwatch held on the last weekend of January and spent one hour counting the birdlife.
Wendy Johnson, RSPB Cymru's Big Garden Birdwatch co-ordinator, said they do not know why the numbers of the house sparrow are falling.
TOP SPECIES IN WALES
Average per garden
Blue tit: 3.8
Great tit: 1.9
Collared dove: 1.3
"It has been declining ever since we started the survey in 1979," she said.
"Numbers are almost 50% down in Wales although it is doing substantially better here than in the rest of the UK.
An average of just 5.2 sparrows were seen in each Welsh garden this year, compared to an average of 10 in 1979.
"It's difficult to know why - it could be down to habitat.
"There are not always the roostings for the birds to nest. That's because modern houses do not have the nooks and crannies the older buildings used to.
"There has to be places for them [sparrows] to find comfort."
She said climate change could also be a factor and part of the purpose of the RSPB annual birdwatch was to monitor the decline.
Numbers of starlings have also continued to drop during the period of the birdwatch - its numbers are down more than 70% since 1979.
It shares its place as the third most common visitor to Welsh gardens with the chaffinch.
But many people who took part noted higher numbers of blackbirds and song thrushes in their gardens. Ms Johnson said this was probably because of the colder winter this year.
The blackbird was also the most widespread species spotted in Wales, recorded in 94% of all gardens.