Richard Du Toit / Cattle Egret (Bubulcus ibis) on Burchell's Zebra (Equus burchellii), Rietvlei Nature Reserve, Gauteng, South Africa

Richard Du Toit / Burchell's Zebra (Equus burchellii) pair, Rietvlei Nature Reserve, Gauteng, South Africa

Piotr Naskrecki / Mantid (Mantidae), Woburn, Massachusetts

Piotr Naskrecki / Turnip-tailed Gecko (Thecadactylus rapicauda), Suriname

Piotr Naskrecki / Three-striped Poison Dart Frog (Ameerega trivittata) male carrying tadpoles, Suriname

David Pattyn / Black necked grebe (Podiceps nigricollis) frontal view of pair mating, La Dombes lake area, France, April

Tim Fitzharris / Siberian Tiger (Panthera tigris altaica) running, native to Russia

Suzi Eszterhas / Mountain Gorilla (Gorilla gorilla beringei) mother holding five month old twin babies, Parc National des Volcans, Rwanda

Suzi Eszterhas / Mountain Gorilla (Gorilla gorilla beringei) mother holding five month old twin babies, Parc National des Volcans, Rwanda

Kevin Schafer / Galapagos Sea Lion (Zalophus wollebaeki) pups playing, Espanola Island, Galapagos Islands, Ecuador

Ingo Arndt / Grizzly Bear (Ursus arctos horribilis) chasing salmon, Lake Clark National Park, Alaska

Ingo Arndt / Grizzly Bear (Ursus arctos horribilis) cub running through shallow water, Lake Clark National Park, Alaska

Ingo Arndt / Shoebill (Balaeniceps rex), Uganda

Suzi Eszterhas / Bengal Tiger (Panthera tigris tigris) six week old cub on sleeping mother at den, Bandhavgarh National Park, India

Suzi Eszterhas / Bengal Tiger (Panthera tigris tigris) mother and four week old cubs at den, Bandhavgarh National Park, India

Donald M. Jones / Mountain Bluebird (Sialia currucoides) male in nest cavity, Troy, Montana

Donald M. Jones / Elk (Cervus elaphus) bull bugling, Jasper National Park, Alberta, Canada

Tui De Roy / Emperor Penguin (Aptenodytes forsteri), Prydz Bay, eastern Antarctica

Theo Allofs / African Elephant (Loxodonta africana), Skeleton Coast, Namib Desert, Namibia

Pete Oxford / African Lion (Panthera leo) male portrait, Moremi Game Reserve, Okavango Delta, Botswana

Andrew Parkinson / Mute swan (Cygnus olor) portrait on water at dawn, Derbyshire, UK, February.

Piotr Naskrecki / Cross Frog (Oreophryne sp) male protecting his clutch of eggs, Papua New Guinea

Piotr Naskrecki / Eastern Fairy Shrimp (Eubranchipus vernalis) in vernal pond, Estabrook Woods, Massachusetts

Christian Ziegler / Bumblebee Orchid (Ophrys bombyliflora) flower and its male Longhorn Bee (Eucera sp) pollinator, Sardinia, Italy

Ingo Arndt / King Penguin (Aptenodytes patagonicus) group returning from the sea, Volunteer Point, Falkland Islands

Donald M. Jones / White-tailed Deer (Odocoileus virginianus) buck in velvet, western Montana

Donald M. Jones / Mountain Pygmy-Owl (Glaucidium gnoma), northwestern Montana

Donald M. Jones / Mountain Pygmy-Owl (Glaucidium gnoma), northwestern Montana. Sequence 1 of 2

Tui De Roy / Baglafecht Weaver (Ploceus baglafecht) male, Borana Ranch, Kenya

Yva Momatiuk & John Eastcott / Alaska Moose (Alces alces gigas) sub-adult bull with antlers shedding velvet feeding in tundra pond, Denali National Park, Alaska

Chien Lee / Spectral Tarsier (Tarsius tarsier), Tangkoko Nature Reserve, Sulawesi, Indonesia

Konrad Wothe / European Bee-eater (Merops apiaster) presents prey item to potential mate, Bulgaria

Matthias Breiter / Kermode Bear (Ursus americanus kermodei), white morph called spirit bear, northern British Columbia, Canada

Matthias Breiter / Ruffed Grouse (Bonasa umbellus) male drumming, Kenora, Ontario, Canada

Chien Lee / Spotted-winged Fruit Bat (Balionycteris maculata) roosting, Bukit Sarang Conservation Area, Bintulu, Borneo, Malaysia

Chien Lee / Lilac-cheeked Kingfisher (Cittura cyanotis), Tangkoko Nature Reserve, Sulawesi, Indonesia

Thomas Marent / Dusky Leaf Monkey (Trachypithecus obscurus) young, Khao Sam Roi Yot National Park, Thailand

Thomas Marent / Bornean White-bearded Gibbon (Hylobates albibarbis), Tanjung Puting National Park, Borneo, Indonesia

Thomas Marent / Alpine Newt (Ichthyosaura alpestris) male, Switzerland

Thomas Marent / Alpine Newt (Ichthyosaura alpestris) female, Switzerland

Thomas Marent / European Tree Frog (Hyla arborea) calling, Switzerland

Konrad Wothe / Rainbow Lorikeet (Trichoglossus haematodus) trio in Umbrella Tree (Schefflera actinophylla), Atherton Tableland, Queensland, Australia

Pete Oxford / Chachi Tree Frog (Hypsiboas picturatus), northwest Ecuador

Mark Raycroft / Chocolate Labrador Retriever (Canis familiaris)

Mark Raycroft / Black Labrador Retriever (Canis familiaris)

Mark Raycroft / Golden Retriever (Canis familiaris)

Mark Raycroft / Golden Retriever (Canis familiaris) puppies

Mark Raycroft / French Bulldog (Canis familiaris) adult and puppy

Mark Raycroft / Basset Hound (Canis familiaris) puppy

Heike Odermatt / Black-browed Albatross (Thalassarche melanophrys) chick begging for food, Falkland Islands

Vincent Grafhorst / African Lion (Panthera leo) male, Khutse Game Reserve, Botswana

Mitsuaki Iwago / Japanese Macaque (Macaca fuscata) mother grooming young, Jigokudani, Japan

Steve Gettle / Black-capped Chickadee (Poecile atricapillus), Kellogg Bird Sanctuary, Michigan

Steve Gettle / Eastern Bluebird (Sialia sialis) male feeding on insect prey, Huron Meadows Metropark, Michigan

Tim Fitzharris / California Sea Lion (Zalophus californianus) looking around on surface, Baja California, Mexico

Sergey Gorshkov / Leopard (Panthera pardus) snarling, Botswana

Steve Gettle / Dark-eyed Junco (Junco hyemalis) on branch with frozen berries, North America

Luciano Candisani / Antillean Manatee (Trichechus manatus manatus) in coastal shallow waters, Brazil

Donald M. Jones / Canada Goose (Branta canadensis) flying, central Montana

Donald M. Jones / Black Bear (Ursus americanus) yearling cub up in a Lodgepole Pine (Larix laricina), Alberta, Canada

Donald M. Jones / American Badger (Taxidea taxus) cub at den, western Montana

Pete Oxford / Black-chested Buzzard-Eagle (Geranoaetus melanoleucus) juvenile, Podocarpus National Park, Ecuador

Sergey Gorshkov / Leopard (Panthera pardus) snarling, Botswana

Sergey Gorshkov / Leopard (Panthera pardus) resting, Botswana

Jasper Doest / Ring-tailed Lemur (Lemur catta) mother with young, Netherlands

Vincent Grafhorst / Koringkriek Armored Bush Cricket (Acanthoplus armativentris), Gaborone Game Reserve, southeast Botswana

Suzi Eszterhas / Sumatran Orangutan (Pongo abelii) two and a half year old baby calling, Gunung Leuser National Park, north Sumatra, Indonesia

Suzi Eszterhas / Black-browed Albatross (Thalassarche melanophrys) flying, Steeple Jason Island, Falkland Islands

ZSSD / African Lion (Panthera leo) male, native to Africa

ZSSD / African Lion (Panthera leo) male, native to Africa

ZSSD / Giant Panda (Ailuropoda melanoleuca) cub, native to China

Michael Quinton / Crab Spider (Diaea dorsata) camouflaged on yellow flower, Alaska

Tui De Roy / Galapagos Sea Lion (Zalophus wollebaeki) female and pup nuzzling, Galapagos Islands, Ecuador

Murray Cooper / Plate-billed Mountain-Toucan (Andigena laminirostris) with orchids, Ecuador

Murray Cooper / Sparkling Violet-ear (Colibri coruscans) hummingbird males fighting, Ecuador, digitally manipulated

Sebastian Kennerknecht / Common Goldeneye (Bucephala clangula) male in breeding plumage on pond, Santa Cruz, Monterey Bay, California

Suzi Eszterhas / Digger Bee (Melissodes sp) pollinating Engelmann Prickly Pear (Opuntia engelmannii) flower, Red Corral Ranch, Texas

Konrad Wothe / Bengal Tiger (Panthera tigris tigris), native to India

Michael Durham / Red-legged Frog (Rana aurora) near Circle Creek along coast, Oregon

Michael Durham / Pallid Bat (Antrozous pallidus) flying at night, Washington

Michael Durham / Pallid Bat (Antrozous pallidus) flying at night, Washington

Michael Durham / Eastern Big-eared Bat (Corynorhinus rafinesquii) flying at night, Big Thicket National Preserve, Texas

Michael Durham / Red Imported Fire Ant (Solenopsis invicta), also known as RIFA, worker portrait, highly invasive introduced species, Texas

Ingo Arndt / Blue Crab (Discoplax hirtipes) in defensive posture, Christmas Island, Indian Ocean, Territory of Australia

Konrad Wothe / Fennec Fox (Vulpes zerda) looking out of den, Libya

Donald M. Jones / Rufous Hummingbird (Selasphorus rufus) male sitting on willow branch, Troy, Montana

Donald M. Jones / American Pika (Ochotona princeps) calling from atop a boulder, Glacier National Park, Montana

Donald M. Jones / Common Starling (Sturnus vulgaris) chick peeking out of nest cavity, western Montana

Donald M. Jones / Blue Grouse (Dendragapus obscurus) male displaying, western Montana

Donald M. Jones / Dall's Sheep (Ovis dalli) bedded ram, central Alaska

Donald M. Jones / Coyote (Canis latrans) six week old pups, western Montana

Donald M. Jones / American Beaver (Castor canadensis) carrying branch over dam, western Montana

Matthias Breiter / Polar Bear (Ursus maritimus) cooling off on a frozen lake, Churchill, Manitoba, Canada

Albert Lleal / Red-footed Tortoise (Geochelone carbonaria), native to South America

Theo Allofs / Celebes Black Macaque (Macaca nigra) pair delousing, Sulawesi, Indonesia

Theo Allofs / Celebes Black Macaque (Macaca nigra) dominant male, Sulawesi, Indonesia