Rolf Nussbaumer / RF- Wild turkey males displaying (Meleagris gallopavo). Texas, USA. (This image may be licensed either as rights managed or royalty free.)

Rolf Nussbaumer / RF- Western Diamondback Rattlesnake (Crotalus atrox), adult in striking pose with rattle raised, in wildflowers. Laredo, Webb County, South Texas, USA. April. (This image may be licensed either as rig...

Rolf Nussbaumer / RF- Northern Raccoon (Procyon lotor) drinking from wetland lake. Fennessey Ranch, Refugio, Coastal Bend, Texas Coast, USA. (This image may be licensed either as rights managed or royalty free.)

Doug Perrine / RF- Green sea turtle (Chelonia mydas) being cleaned by herbivorous cleaner fish species Yellow tangs (Zebrasoma flavescens) and Gold-ring surgeonfish (Ctenochaetus strigosus) that graze algae on turtl...

Rolf Nussbaumer / RF- Vermilion Flycatcher (Pyrocephalus rubinus) male giving insect to female for young in nest. Lake Corpus Christi, Texas, USA. May. (This image may be licensed either as rights managed or royalty fr...

Rolf Nussbaumer / RF- Bullfrog (Rana catesbeiana) adult on American lotus lilypad. Welder Wildlife Refuge, Sinton, Texas, USA. (This image may be licensed either as rights managed or royalty free.)

Rolf Nussbaumer / RF- Green treefrog (Hyla cinerea) on yellow waterlily. Welder Wildlife Refuge, Sinton, Texas, USA. (This image may be licensed either as rights managed or royalty free.)

Nick Garbutt / RF - Herd of American Bison (Bison bison) around geo-thermal features. Firehole River Valley. Yellowstone National Park, Wyoming, USA. January 2008. (This image may be licensed either as rights manage...

Nick Garbutt / RF - Rocky Mountain bighorn sheep (Ovis canadensis canadensis) searching for grazing beneath deep snow. Lamar Valley, Yellowstone National Park, Wyoming, USA. January. (This image may be licensed eith...

Nick Garbutt / RF - Moon beam created by reflections from ice crystals in air, at full moon over Grand Canyon, Yelllowstone National Park, Wyoming, USA. January 2016. (This image may be licensed either as rights ma...

Nick Garbutt / RF - Sun beam created by reflections from ice crystals in air at sun rise over Grand Canyon, Yelllowstone National Park, Wyoming, USA. January 2016. (This image may be licensed either as rights manage...

Nick Garbutt / RF - North American bobcat (Lynx rufus). Madison River Valley, Yellowstone National Park, Wyoming, USA. January. (This image may be licensed either as rights managed or royalty free.)