Duncan Murrell / Bornean keeled pit viper (Tropidolaemus subannulatus) in the Sabangau (peat-swamp) Forest, Central Kalimantan, Indonesia.

Duncan Murrell / Bornean keeled pit viper (Tropidolaemus subannulatus) in the Sabangau (peat-swamp) Forest, Central Kalimantan, Indonesia.

Duncan Murrell / Bornean keeled pit viper (Tropidolaemus subannulatus) juvenile in the Sabangau (peat-swamp) Forest, Central Kalimantan, Indonesia.

Chien Lee / Borneo Keeled Pit Viper (Tropidolaemus subannulatus) smelling, Tibu, Batang Ai National Park, Malaysia

Chien Lee / Borneo Keeled Pit Viper (Tropidolaemus subannulatus) with extended tongue, Kubah National Park, Borneo, Malaysia

Neil Aldridge / Bornean keeled green pit viper (Tropidolaemus subannulatus) climbing along branch in rainforest, Lower Kinabatangan Segama Wetlands, Sabah, Borneo, Malaysia.

Neil Aldridge / Bornean keeled green pit viper (Tropidolaemus subannulatus) flicking its tongue, Lower Kinabatangan Segama Wetlands, Sabah, Borneo, Malaysia.

Neil Aldridge / Tracking shot of Bornean keeled green pit viper (Tropidolaemus subannulatus) head as it flicks its tongue while climbing up a branch in rainforest, Lower Kinabatangan Segama Wetlands, Sabah, Borneo, M...

Neil Aldridge / Close up of Bornean keeled green pit viper (Tropidolaemus subannulatus) head as it looks around, Lower Kinabatangan Segama Wetlands, Sabah, Borneo, Malaysia.

Neil Aldridge / Close up of Bornean keeled green pit viper (Tropidolaemus subannulatus) head as it flicks its tongue out, Lower Kinabatangan Segama Wetlands, Sabah, Borneo, Malaysia.

Neil Aldridge / Close up of Bornean keeled green pit viper (Tropidolaemus subannulatus) head as it flicks its tongue while climing up a branch and leaving frame, Lower Kinabatangan Segama Wetlands, Sabah, Borneo, Mal...

Lucas Bustamante / Bornean keeled green pit viper (Tropidolaemus subannulatus) portrait, Danum Valley, Sabah, Malaysia.

Solvin Zankl / Moor frog (Rana arvalis) mating pair in pond, Germany

Solvin Zankl / Moor frog (Rana arvalis) group of males in water, Germany

Dietmar Nill / Moor frogs (Rana arvalis) mating in a pond, Germany (the male is blue)

Artur Tabor / Moor frogs and frogspawn (Rana arvalis) Poland

Silvia Reiche / Moor Frog (Rana arvalis) male, Netherlands

Konrad Wothe / Moor Frog (Rana arvalis) pair in amplexus, Bavaria, Germany

Konrad Wothe / Moor Frog (Rana arvalis), Bavaria, Germany

Jussi Murtosaari / Moor frog (Rana arvalis) adult on grass, Joutsa (formerly Leivonmaki), Finland, February, May.

Sandra Bartocha / Moor Frog (Rana arvalis) Mecklenburg-Vorpommern, Germany, April

Sandra Bartocha / Moor Frogs (Rana arvalis) gathered in pond to breed, with males in blue breeding colours. Crack Willow (Salix fragilis) trees grwoing along the waters edge, Germany, April

Sandra Bartocha / Moor Frog (Rana arvalis) group with males in breeding colouration with Crack Willow (Salix fragilis) trees at the waters edge, Germany, April

Sandra Bartocha / Moor Frog (Rana arvalis) males, in breeding coloration, Germany, April