David Perpinan / Common rock sparrow (Petronia petronia) feeding chicks in nest, filmed using an infra-red camera, Cuenca, Castile-La Mancha, Spain, June.

David Perpinan / Common rock sparrow (Petronia petronia) chick exploring outside nest, Cuenca, Castile-La Mancha, Spain, June.

David Perpinan / Adult Common rock sparrow (Petronia petronia) feeding chicks, Cuenca, Castile-La Mancha, Spain, June.

David Perpinan / Female Rock sparrow (Petronia petronia) feeding chick inside nest, filmed with an infrared camera, Spain, June.

David Perpinan / Rock sparrow (Petronia petronia) feeding chick outside nest, Spain, June.

Dong Lei / Rufous-necked snowfinch (Pyrgilauda ruficollis) with insects in beak, feeding chicks at nest in rock hollow. Sanjiangyuan National Nature Reserve, Qinghai Province, Qinghai-Tibet Plateau, China. Augus...

Dong Lei / Rufous-necked snowfinch (Pyrgilauda ruficollis) adult with begging chicks at nest in rock hollow. Sanjiangyuan National Nature Reserve, Qinghai Province, Qinghai-Tibet Plateau. August.

Loic Poidevin / Rock bunting (Emberiza cia) Leon, Spain, February.

Loic Poidevin / Rock bunting (Emberiza cia) in the snow, Leon, Spain, February.

Loic Poidevin / Rock bunting (Emberiza cia) In the snow with Rowan (Sorbus acuparia) berries Leon, Spain, February

David Tipling / Rock sparrow (Petronia petronia) Extremadura, Spain. December

David Perpinan / Three Common rock sparrows (Petronia petronia) on a window ledge near nest, Cuenca, Castile-La Mancha, Spain, June.