Male black grouse (Lyrurus tetrix) fighting on snow covered field, Finland

Striated caracara (Phalcoboenus australis) feather detail, on Carcass Island in the Falkland Islands, South Atlantic Ocean, South America

Adult imperial shag (Phalacrocorax (atriceps) atriceps) in flight in the Falkland Islands, South Atlantic Ocean, South America

Black-browed albatross (Thalassarche melanophrys) close-up at breeding colony on Carcass Island in the Falkland Islands

Adult black guillemot (Cepphus grylle) in summer plumage near Vigur Island in Isafjardardjup Bay, Iceland

Adult dovekies (Little Auk) (Alle alle) at their breeding site amongst scree slopes at Rubini Rock, Tikhaya Bay, Hooker Island, Franz Josef Land, Russia, Arctic Ocean, Eurasia

Adult black-legged kittiwake (Rissa tridactyla) in combat with a second kittiwake near Alexander Island, Franz Josef Land, Russia, Arctic Ocean, Eurasia

Adult Galapagos Petrel (Pterodroma phaeopygia) (Patapegada) nesting on the upslope grasslands of Santa Cruz Island in the Galapagos Island Archipelago, UNESCO World Heritage Site, Ecuador, South America

Researcher catching Rufous-tailed Hummingbird (Amazilia Tzacatl) in a net set up for pollination study, rainforest at "La Selva" research station in Puerto Viejo de Sarapiqui, Costa Rica

Researcher measuring a 2.6 gram Stripe-throated Hermit hummingbird wing as part of a pollination study, rainforest at the "La Selva" research station in Puerto Viejo de Sarapiqui, Costa Rica

Researcher photographing a 2.6 gram Stripe-throated Hermit hummingbird as part of a pollination study, rainforest at the "La Selva" research station in Puerto Viejo de Sarapiqui, Costa Rica

Researchers picking up pollen with a brush from the beak of a Rufous-tailed hummingbird as part of a pollination study, rainforest at the "La Selva" research station in Puerto Viejo de Sarapiqui , Costa Rica

Researcher setting up a net to capture hummingbirds as part of a pollination study, rainforest at the "La Selva" research station in Puerto Viejo de Sarapiqui, Costa Rica

Rufous-tailed Hummingbird (Amazilia tzacatl) in a net set up by a researcher as part of a pollination study, rainforest at the "La Selva" research station in Puerto Viejo de Sarapiqui, Costa Rica

Researchers picking up pollen with a brush from the beak of a hummingbird Stripe-throated Hermit as part of a pollination study, rainforest at the "La Selva" research station in Puerto Viejo de Sarapiqui, Costa Rica

Researcher measuring the beak of a Rufous-tailed hummingbird as part of a pollination study, rainforest at the "La Selva" research station in Puerto Viejo de Sarapiqui, Costa Rica

Researchers picking up pollen using tape on the beak of a Rufous-tailed hummingbird as part of a pollination study, rainforest at the "La Selva" research station in Puerto Viejo de Sarapiqui, Costa Rica