Bence Mate / Orange chinned parakeets (Brotogeris jugularis) two looking at each other, Santa Rita, Costa Rica.

Juergen Freund / Flock of Budgerigars (Melopsittacus undulatus ) drinking in an outback dam, Northern Territory, Australia.

Gabriel Rojo / Monk parakeet (Myiopsitta monachus) Calden Forest , La Pampa , Argentina

Pete Oxford / Caribbean Parakeet or Brown-throated Parakeet (Aratinga pertinax xanthogenia) Bonaire, Netherlands Antilles, Caribbean

Mark Carwardine / Mauritius / Mascarene / Echo parakeet (Psittacula eques) flying, threatened / endangered species, Black River Gorges, Mauritius, Indian Ocean, wild

Mark Carwardine / Mauritius / Mascarene / Echo parakeet (Psittacula eques) threatened / endangered species, Black River Gorges, Mauritius, Indian Ocean, wild

Mark Carwardine / Mauritius / Mascarene / Echo parakeet (Psittacula eques) Threatened / endangered species, Mauritian Wildlife Foundation breeding centre, Mauritius, captive

Mark Carwardine / Mauritius / Mascarene / Echo parakeet (Psittacula eques) Threatened / endangered species, Mauritian Wildlife Foundation breeding centre, Mauritius, captive

Wild Wonders of Europe / Geslin / Monk parakeet (Myiopsitta monachus) pair perched in tree in the Vatican garden, Rome, Italy, March 2010

Wild Wonders of Europe / Geslin / Monk parakeet (Myiopsitta monachus) pair perched in tree in the Vatican garden, Rome, Italy, March 2010

Rolf Nussbaumer / Flock of Green parakeets flying {Aratinga holochlora} Texas, USA

Rolf Nussbaumer / Green parakeet pair {Aratinga holochlora} Texas, USA.

Andy Rouse / Rose-ringed parakeet (Psittacula krameri) taking off. Ranthambhore National Park, India.

Andy Rouse / Rose-ringed parakeet (Psittacula krameri) taking off. Ranthambhore National Park, India.

Staffan Widstrand / Rose-ringed parakeet (Psittacula krameri) Keoladeo Ghana National Park, Bharatpur, Rajasthan, India

Lucas Bustamante / Rose-ringed parakeet (Psittacula krameri) Yala National Park, Southern Province, Sri Lanka

Bernard Castelein / Rose-ringed parakeet (Psittacula krameri), eating wild fruit, Keoladeo NP, Bharatpur, India

Karine Aigner / Cuban parakeet (Psittacara euops) Bermejas, Cuba.

Axel Gomille / Rose-ringed parakeet (Psittacula krameri), female feeding, Rajasthan, India

Lucas Bustamante / Five Cobalt-winged parakeets (Brotogeris cyanoptera) perched on leaves, Yasuni National Park, Orellana, Ecuador.

Phil Savoie / Crimson fronted parrot (Aratinga finschi) La Selva Field Station, Costa Rica.

Phil Savoie / Crimson fronted parrot (Aratinga finschi) La Selva Field Station, Costa Rica.

Jiri Lochman / Mallee ringneck parakeet (Barnardius barnardi) Willandra Lakes UNESCO Natural World Heritage Site, New South Wales, Australia.

Claudio Contreras / Socorro Parakeet (Aratinga holochlora brevipes), Socorro Island, Revillagigedo Archipelago Biosphere Reserve / Archipielago de Revillagigedo UNESCO Natural World Heritage Site (Socorro Islands), Pacif...

Claudio Contreras / Socorro Parakeet (Aratinga holochlora brevipes) pair, Socorro Island, Revillagigedo Archipelago Biosphere Reserve / Archipielago de Revillagigedo UNESCO Natural World Heritage Site (Socorro Islands),...

Claudio Contreras / Socorro Parakeet (Aratinga holochlora brevipes) preening, Socorro Island, Revillagigedo Archipelago Biosphere Reserve / Archipielago de Revillagigedo UNESCO Natural World Heritage Site (Socorro Island...

Claudio Contreras / Socorro Parakeet (Aratinga holochlora brevipes), Socorro Island, Revillagigedo Archipelago Biosphere Reserve / Archipielago de Revillagigedo UNESCO Natural World Heritage Site (Socorro Islands), Pacif...

Claudio Contreras / Socorro Parakeet (Aratinga holochlora brevipes) pair, Socorro Island, Revillagigedo Archipelago Biosphere Reserve / Archipielago de Revillagigedo UNESCO Natural World Heritage Site (Socorro Islands),...

Claudio Contreras / Socorro Parakeet (Aratinga holochlora brevipes) in nest, Socorro Island, Revillagigedo Archipelago Biosphere Reserve / Archipielago de Revillagigedo UNESCO Natural World Heritage Site (Socorro Islands...

Claudio Contreras / Socorro Parakeet (Aratinga holochlora brevipes) in nest, Socorro Island, Revillagigedo Archipelago Biosphere Reserve / Archipielago de Revillagigedo UNESCO Natural World Heritage Site (Socorro Islands...

Claudio Contreras / Socorro Parakeet (Aratinga holochlora brevipes), Socorro Island, Revillagigedo Archipelago Biosphere Reserve / Archipielago de Revillagigedo UNESCO Natural World Heritage Site (Socorro Islands), Pacif...

Melvin Grey / Orange-chinned parakeet (Brotogeris jugularis) adult. Costa Rica

Georgette Douwma / Rose-ringed parakeet (Psittacula krameri) with fledgling Starling (Sturnus vulgaris) on bird feeder. London, UK.

Georgette Douwma / Rose-ringed / Ring-necked parakeets (Psittacula krameri) on bird feeders. London, UK.

Georgette Douwma / Rose-ringed / Ring-necked parakeets (Psittacula krameri) on bird feeder. London, UK.

Georgette Douwma / Rose-ringed / Ring-necked parakeets (Psittacula krameri) on bird feeder. London, UK.

Georgette Douwma / Rose-ringed / Ring-necked parakeets (Psittacula krameri) squabbling on bird feeder. London, UK.

Cyril Ruoso / Rose-ringed Parakeet (Psittacula krameri) introduced species feeding in tree, Paris region, France, September

Cyril Ruoso / Rose-ringed Parakeet (Psittacula krameri) introduced species feeding in tree, Paris region, France, September

Cyril Ruoso / Rose-ringed Parakeet (Psittacula krameri) introduced species perching in tree, Paris region, France, September

Cyril Ruoso / Rose-ringed Parakeet (Psittacula krameri) introduced species, at nest in tree, Paris region, France, August

Cyril Ruoso / Rose-ringed Parakeet (Psittacula krameri) introduced species, at nest in tree, Paris region, France, August

Cyril Ruoso / Rose-ringed Parakeet (Psittacula krameri) introduced species, at nest in tree, Paris region, France, August

Cyril Ruoso / Rose-ringed Parakeet (Psittacula krameri) introduced species, at nest in tree, Paris region, France, August

Cyril Ruoso / Rose-ringed Parakeet (Psittacula krameri) introduced species, feeding in tree, Paris region, France, August

Cyril Ruoso / Rose-ringed Parakeet (Psittacula krameri) introduced species, feeding in tree, Paris region, France, August

Cyril Ruoso / Rose-ringed Parakeet (Psittacula krameri) introduced species, blurred motion of flying in front of tree, Paris region, France, August

Pete Oxford / Rose-ringed parakeets (Psittacula krameri manillensis) perched, National Chambal Gharial Wildlife Sanctuary, Madhya Pradesh, India.

Agustin Esmoris / Blue-crowned Parakeet (Aratinga acuticaudata), Buenos Aires, Argentina

Loic Poidevin / Rose ringed parakeet (Psittacula krameri) female at nest in tree hole. Kaziranga National Park, Assam, India.

Loic Poidevin / Red-breasted parakeet (Psittacula alexandri) pair. Kaziranga National Park, Assam, India.

Markus Varesvuo / Alexandrine parakeet (Psittacula eupatria) in flight, United Arab Emirates, November

Floris van Breugel / Green parakeet (Aratinga holochlora) flock flying together, Sima de las Cotorras, Chiapas, Mexico. March.

Floris van Breugel / Green parakeet (Aratinga holochlora) flock flying together, Sima de las Cotorras, Chiapas, Mexico. March.

Brent Stephenson / Adult Red-crowned parakeet (Cyanoramphus novaezelandiae) foraging on totara (Podocarpus) fruits in the sub-canopy. Ulva Island, Stewart Island, New Zealand, February.

Brent Stephenson / Adult Yellow-crowned parakeet (Cyanoramphus auriceps) perched in a tree, showing the yellowish belly and forehead. Hawdon Valley, Canterbury, New Zealand, January.

Brent Stephenson / Adult female Antipodes Island parakeet (Cyanoramphus unicolor) in fresh plumage, standing on a rock with tussocks in the background. Auckland Zoo, Auckland, New Zealand, February. Captive, Vulnerable...

Brent Stephenson / Adult male Antipodes Island parakeet (Cyanoramphus unicolor) in fresh plumage, feeding. Auckland Zoo, Auckland, New Zealand, February. Captive, Vulnerable species.

Tui De Roy / Red-crowned Parakeet (Cyanoramphus novaezeelandiae hochstetteri) feeding on Anisotome megaherb seeds. Antipodes Island, New Zealand.

Tui De Roy / Red-crowned Parakeet (Cyanoramphus novaeseelandiae) Enderby Island, Auckland Islands Group, New Zealand.

Tui De Roy / Antipodes Parakeet (Cyanoramphus unicolor) foraging in tussock grass (Poa litorosa) Antipodes Island, New Zealand.

Tui De Roy / Antipodes Parakeet (Cyanoramphus unicolor) foraging in tussock grass (Poa litorosa) Antipodes Island, New Zealand.

Tui De Roy / Antipodes Island Parakeet (Cyanoramphus unicolor) foraging in tussock grass (Poa litorosa) Antipodes Island, New Zealand.

Tui De Roy / Antipodes Parakeet (Cyanoramphus unicolor) foraging in tussock grass (Poa litorosa) Antipodes Island, New Zealand.

Steve Gettle / Nanday Parakeet (Nandayus nenday), Fort Desoto Park, Florida

Glenn Bartley / Cliff Parakeet (Myiopsitta luchsi)atop cactus, Bolivia

Glenn Bartley / Cliff Parakeet (Myiopsitta luchsi) atop cactus, Bolivia

Tim Laman / Cobalt-winged Parakeets (Brotogeris cyanoptera) eating clay at clay lick east of Anangu and south of the Napo River, Yasuni National Park, Orellana Province, Ecuador, July.

Albert Lleal / Budgerigar (Melopsittacus undulatus) pair under visible light

Ole Jorgen Liodden / Red-crowned Parakeet (Cyanoramphus novaezelandiae) portrait, vulnerable species, Auckland Island, New zealand. November.

Daniel Heuclin / Bolivian Blue-crowned Parakeet / Conure (Aratinga acuticaudatus neumanni). Captive. Santa Cruz, Bolivia.

Luiz Claudio Marigo / Maroon / Reddish bellied parakeet (Pyrrhura frontalis) two perched on branch, mountainous Atlantic Rainforest of Serra Bonita Natural Private Heritage Reserve (RPPN Serra Bonita) municipality of Camac...

Roland Seitre / Flock of Cobalt-winged Parakeet (Brotogeris cyanoptera) feeding on clay which provides some minerals they require. Madre de Dios, Peru, September.

Roland Seitre / Flock of Cobalt-winged Parakeet (Brotogeris cyanoptera) and Black-capped Parakeet (Pyrrhura rupicola) in shade under tree. Madre de Dios, Peru, September.

Martin Willis / Budgerigar (Melopsittacus undulatus) flock flying, Boulia, Queensland, Australia

Brent Stephenson / Red-crowned Parakeet (Cyanoramphus novaezelandiae) perched on a log on forest floor. Tiritiri Matangi Island, Auckland, New Zealand, September.

Hanne & Jens Eriksen / Rose ringed parakeet (Psittacula krameri) drinking, Oman, January

Konrad Wothe / Red-crowned Parakeet (Cyanoramphus novaezelandiae) perched. Enderby Island, New Zealand.

David Welling / Green Parakeet (Aratinga holochlora) perching. Laredo Webb County, Texas, USA, May.

David Welling / Green Parakeet (Aratinga holochlora) perching. Laredo Webb County, Texas, USA, May.

Luiz Claudio Marigo / Yellow-chevroned Parakeets (Brotogeris chiriri) eating the fruit of Siriguela tree (Spondias purpurea). The Pantanal wetlands of Mato Grosso State, Brazil, October.

Luiz Claudio Marigo / Reddish / Marron-bellied parakeet (Pyrrhura frontalis) perched in Hibiscus tree, Atlantic Rainforest of Serrinha do Alambari Environmental Protection Area, Resende, Rio de Janeiro State, Brazil.

Mark Carwardine / Mauritius / Mascarene / Echo parakeets (Psittacula eques) in habitat, threatened / endangered species, Black River Gorges, Mauritius, Indian Ocean, wild

Mark Carwardine / Mauritius / Mascarene / Echo parakeet (Psittacula eques) threatened / endangered species, Black River Gorges, Mauritius, Indian Ocean, wild

Mark Carwardine / Mauritius / Mascarene / Echo parakeet (Psittacula eques) Threatened / endangered species, Mauritian Wildlife Foundation breeding centre, Mauritius, captive

Mark Carwardine / Mauritius / Mascarene / Echo parakeet (Psittacula eques) Threatened / endangered species, Mauritian Wildlife Foundation breeding centre, Mauritius, captive

Mark Carwardine / Mauritius / Mascarene / Echo parakeet (Psittacula eques) feeding in cage at feeding bowls, Threatened / endangered species, Mauritian Wildlife Foundation breeding centre, Mauritius, captive

Mark Carwardine / Mauritius / Mascarene / Echo parakeet (Psittacula eques) Threatened / endangered species, Mauritian Wildlife Foundation breeding centre, Mauritius, captive

Mark Carwardine / Mauritius / Mascarene / Echo parakeet (Psittacula eques) Threatened / endangered species, Mauritian Wildlife Foundation breeding centre, Mauritius, captive

Mark Carwardine / Mauritius / Mascarene / Echo parakeet (Psittacula eques) Threatened / endangered species, Mauritian Wildlife Foundation breeding centre, Mauritius, captive

Wild Wonders of Europe / Geslin / Monk parakeet (Myiopsitta monachus) pair perched in tree in the Vatican garden, Rome, Italy, March 2010

Murray Cooper / Golden-plumed Parakeet (Leptosittaca branickii), Ecuador

Murray Cooper / Golden-plumed Parakeet (Leptosittaca branickii) pair, Ecuador

Murray Cooper / Golden-plumed Parakeet (Leptosittaca branickii), Ecuador

Dietmar Nill / Rose ringed / Ringnecked parakeet (Psittacula krameri) in flight, Mannheim, Germany, invasive alien species