Fergus Gill / Tree sparrows (Passer montanus) perching on a branch in the rain. Perthshire, Scotland, December.

Niall Benvie,Niall Benvie / Tree Sparrow (Passer montanus) on barbed wire, against white background (field studio). Scotland, January.

Loic Poidevin / Eurasian tree sparrow (Passer montanus) perched on branch. Finland. May.

Markus Johannsen/ BIA / Eurasian Tree Sparrow (Passer montanus) juvenile calling, Lower Saxony, Germany

Ann & Steve Toon / House sparrows (Passer domesticus) and tree sparrow (Passer montanus) (right), Caerlaverock WWT, Dumfries & Galloway, Scotland, UK, October

Konrad Wothe / Tree sparrows (Passer montanus) in snow, Bavaria, Germany, March.

Konrad Wothe / Blue tit (Cyanistes caeruleus) and Tree sparrow (Passer montanus) at feeder in winter, Bavaria, Germany, February.

Andy Trowbridge / Eurasian Tree Sparrow (Passer montanus) perched on branch in snow. Southern Norway. January.

Fabrice Cahez / Eurasian tree sparrow (Passer montanus) Vosges, France, January.

Fabrice Cahez / Eurasian tree sparrow (Passer montanus) Vosges, France, January.

Hermann Brehm / Tree Sparrow (Passer montanus), Bayern, Germany. December

Hermann Brehm / Tree Sparrow (Passer montanus) pair mating, Bayern, Germany. July