Berried shrubs are often planted for birds but I don’t feel a great need to do that here since the birds eat every fruit I grow, from raspberries to rose hips. The orange sorbus ripen early (which I am not that keen on because it seems to bring autumn into the garden prematurely) and the birds strip them by autumn. The yellow-berried rowans such as the famous ‘Joseph Rock’ are supposed to last better before the birds decide to strip the berries from the branches but, in my experience, they don’t last much longer.
So I am very keen on Sorbus cashmeriana, a small tree that has a lot of good features. It is not difficult to guess where it comes from and like other Asian sorbus has oddly coloured berries. In this case they are pure white, and larger than average, like bright marbles festooning the bare branches well into winter. The leaves are blue/green in summer, finely divided like the other rowans or mountain ash. They have good autumn colour too, before they drop. Apart from the unusual colour and size of the berries the flowers are nice too. Most sorbus have flat or domed heads of small, white blooms in late spring but in this case the blooms are a bit larger and tinged with pink.
It is not too fussy about soil, as long as it is not wet, and will grow in most gardens as long as the soil is not thin chalky soils. They are not truly calcifuge but very alkaline soils are best avoided. In time this tree will reach about 8m high and almost as much across, making it a good tree for a small garden with a long season of interest. Planted in grass it will make a nice specimen (why not plant three!) and the berries may well still be hanging there when the snowdrops, which you generously planted in the grass underneath, are starting to bloom.