The Eurasian tree sparrow (Passer montanus) is recognizable by his chestnut brown crown and nape plus his pure white cheeks with a black patch.
Their untidy nest is built in a natural cavity, a hole in a building or the disused nest of a European magpie or white stork.
They are listed as endangered.
Their numbers have rapidly declined since 1990. There are 50% less of these birds now (in the Netherlands), compared to 1990.
You can help them by planting hedges and keep messy wood walls in your garden. And support your local bird conservation programmes.