Ingo Arndt / Brown / Grizzly Bear (Ursus arctos horribilis) tracks on tidal flats, Alaska, USA

Axel Gomille / Wolf (Canis lupus) footprints, Saxony-Anhalt, Germany, August.

Axel Gomille / Wolf (Canis lupus) footprints in tire tracks, Saxony-Anhalt, Germany, August.

Axel Gomille / Wolf (Canis lupus) footprints, Saxony, Germany, July.

Axel Gomille / Wolf (Canis lupus) footprints, Saxony, Germany, August.

Sergey Gorshkov / Wolf (Canis lupus) paw print, Putoransky State Nature Reserve, Putorana Plateau, Siberia, Russia

Franco Banfi / Polar bear (Ursus maritimus) footprints compared to print from human shoe, Spitsbergen, Svalbard, Norway, Arctic Ocean.

Franco Banfi / Polar bear (Ursus maritimus) footprints, Spitsbergen, Svalbard, Norway, Arctic Ocean.

Bruno D'Amicis / Marsican / Abruzzo brown bear (Ursus arctos marsicanus) footprint next to human hand print. Critically endangered subspecies. Central Apennines, Abruzzo, Italy.

Dong Lei / Snow leopard (Panthera uncia) footprint on riverbank, Sanjiangyuan National Nature Reserve, Qinghai Hoh Xil UNESCO World Heritage Site, Qinghai-Tibet Plateau, Qinghai Province, China.

Bruno D'Amicis / Wild Apennine wolf (Canis lupus italicus) track in mud on a forest trail. Central Apennines, Abruzzo, Italy. September. Italian endemic subspecies.

Bruno D'Amicis / Wild Apennine wolf (Canis lupus italicus) tracks in snow. Central Apennines, Abruzzo, Italy. February.