Results from 284,618 people about animals they spot in their gardens over the year also saw sitings of other wildlife including badgers, slow worms and grass snakes fall on at least a monthly basis this year, compared to 2015.
The RSPB wants gardeners to create habitats such as small ponds, bug hotels and pollen-rich plants in window boxes.
The survey revealed that the number of people seeing hedgehogs at least once a month has fallen from 28 per cent last year to 25 per cent this year.
Grey squirrels and badgers were seen most often.
Daniel Hayhow, RSPB conservation scientist, said: "With the right care and attention your garden could become a home to all kinds of different species, and you could have front row seats to some amazing wildlife shows.
"By providing shelter and a safe place to make a home, gardens provide an invaluable resource and are a key element in helping to save nature, perhaps even playing a pivotal role in reversing some declines."