Alan Williams / Dunlin (Calidris alpina) probing for food on the shore, Yell, Shetland, UK, May

Jussi Murtosaari / Garden warbler (Sylvia borin), catching flies in willow tree, Korpoo, Uto, Finland, May.

Andres M. Dominguez / Bacteria (Lepthotryx discophora) causing iridescent patterns and White willow tree leaf (Salix alba) in river, Sierra de Grazalema Natural Park, southern Spain, November.

Sven Zacek / Misty lake, with trees reflected in the water, and Willow (Salix) trees silhouetted on the shore, Suur Emajogi river, Tartumaa, Estonia, May 2014.

Ernie Janes / Blue tit (Cyanistes caeruleus) hanging on Pussy willow branch, Norfolk, England, UK, April.

Alex Hyde / Peacock butterfly (Inachis io) feeding on Goat Willow catkins (Salix caprea), an important food source for pollinators in early spring. Peak District National Park, UK. April.

Nick Upton / Eurasian beaver (Castor fiber) gnawing the trunk of a Willow tree (Salix sp.) in woodland enclosure at night. Devon Beaver Project, run by Devon Wildlife Trust, Devon, UK, April. Taken by a remote cam...

Markus Varesvuo / Willow grouse (Lagopus lagopus) Kiilopaa, Inari, Finland, January.

Markus Varesvuo / Willow Grouse (Lagopus lagopus) in flight over snowy landscape, Utsjoki, Finland April

Markus Varesvuo,Markus Varesvuo / Willow grouse (Lagopus lagopus) in winter plumage, Utsjoki, Finland, April.

Chris Gomersall / 2020VISION / Willow warbler (Phylloscopus trochilus) singing in birch tree at Frensham Common nature reserve, Surrey, England, UK, April

Guy Edwardes / 2020VISION / Pussy willow catkins (Salix caprea), Somerset Levels, Somerset, England, UK, April

Guy Edwardes / 2020VISION / Pussy willow catkin (Salix caprea) bursting out from bud, Somerset Levels, Somerset, England, UK, April