Looks to be a hawthorn.

J.M., the Latin genus is Crataegus; which may help you look up the species. It's a pretty plant.

Fruits pictured are under 1cm, or less than 10mm.

Haws, as in 'Hips and Haws' ie the fruit of the Hawthorn, Crataegus sp. as others have said. In Germany it is probably C monogyna. The size is normal.

A grate food source for birds in winter.

Thank you for the replies. I made a quick check and indeed it is the C. monogyna. Seems like it has some medicinal uses, but not too much used as food source even in old times. Has anyone tasted it? What is the flavour? Is it good?

It is mostly seed with just a little tasteless mushy flesh around it. It can be used alone or with other wild fruit in hedgerow jelly. If you Google 'Hawthorn berry recipes' you'll get lots of hits from British sites.

Mayhaw jelly, made from the fruit of several Crataegus species native to the Southeastern US is a 'delicacy'... those C.monogyna fruits look like they'd be a good candidate for jelly - with or without other berries in the mix.