Danny Green / Hazel Dormouse (Muscardinus avellanarius) hibernating amongst leaves and acorns. Captive. Leicestershire, UK, October.

Alex Hyde / Group of Tissue moths (Triphosa dubitata) hibernating in a limestone cave. Peak District National Park, Derbyshire, UK. November.

Ingo Arndt / Hedgehog (Erinaceus europaeus) hibernating hidden in leaves, Germany, captive.

Ingo Arndt / Mass of Ladybirds (Hippodamia convergens) hibernating on pine tree bark, California, USA

Floris van Breugel / Monarch butterflies (Danaus plexippus) over winter on Eucalyptus and Monterey Cypress trees near Pismo Beach, San Luis, California, USA December.. When temperatures warm up enough, they will embark on...

Ann & Steve Toon / Hedgehog (Erinaceus europaeus) curled up sleeping in autumn leaves, UK, June, captive.

Inaki Relanzon / Lesser Horseshoe Bat (Rinolophus hipposideros) hibernating in Forat de l'Or cave in Terradets Canyon, Pyrenees, Lleida, Catalonia, Spain, December

Paul Harcourt Davies,Paul Harcourt Davies / Lesser Horseshoe Bat (Rhinolophus hipposideros) hibernating in an Etruscan tomb, Podere Montecucco, near Orvieto, Umbria, Italy, November

Claudio Contreras / Monarch butterfly (Danaus plexippus) hibernating, Mariposa Monarca Special Biosphere Reserve, central Mexico, January.

Claudio Contreras / Monarch butterfly (Danaus plexippus) hibernating, Mariposa Monarca Special Biosphere Reserve, central Mexico, January.

Ross Hoddinott / 2020VISION / Large blue butterfly (Maculinea arion) on a Common Centaury (Centaurium erythraea) flower, Collard Hill, Somerset, England, UK, June 2011. Did you know? The large blue's life cycle is dependent on the...

Terry Whittaker / 2020VISION / Hazel dormouse (Muscardinus avellanarius), Kent, UK. Members of Kent Mammal Group conduct monthly dormouse survey, torpid dormouse hibernating in nest box in coppiced woodland, November 2011. Did you...