For further information about recently extinct species you may wish to consult the following internet resources. Please suggest any relevant links that you think belong here.
IUCN Red List The IUCN's Red List of threatened taxa is widely considered the world's most authoritative. Although predominantly concerned with species which still survive, it nonetheless has a strong representation of species which have become extinct since 1500 AD.
The Sixth Extinction Website (TSEW) The original website about recently extinct species, run by Peter Maas. It contains a wealth of information, including lists of recently extinct species grouped taxonomically.
The Sixth Extinction Forum The biggest and best forum on recently extinct animals, run by Peter Maas. The companion forum to the Vanishing Plants forum, run by Melanie Nayyal. You will need to register an account to view all the threads, but it is well worth the effort.
The Vanishing Plants Forum A forum on recently extinct plants, which are often left out of the discussion on the "sixth mass extinction". You will need to register an account to view all the threads, but it is well worth the effort.
Modern Extinction Modern Extinction attempts to bring species extinct during the 21st century to life for the general public.
Lost Amphibians of India The list of amphibian species endemic to the Indian sub-continent which are currently "missing".
Amphibian Rescue A list of all currently missing amphibians around the world, created by the Panama Amphibian Rescue and Conservation Project. The rest of their site is excellent too!
Endangered Species International A spreadsheet type webpage with the names and other important information, including references, of recently extinct species. A tab allows you to switch between animals and plants.
Extinction Countdown News and research about endangered species from around the world
Mongabay "Mongabay is a non-profit provider of conservation and environmental science news."
The Grey Ghost The South Island Kōkako Charitable Trust (SIKCT) attempts to record possible sightings of the South Island kōkako (Callaeas cinereus) and organise and encourage expeditions and searches for this elusive bird.
Save the Bilby Fund Australia's remaining Bilby species (Macrotis lagotis) is highly endangered and threatened with extinction. The Fund aims to raise awareness of the Bilby's plight, and to proactively preserve it through such means as the construction of predator free enclosures, school visits, and the famous (and very yummy!) chocolate Easter Bilby's.
Friends of the Western Swamp Tortoise "To aid local, national and international awareness of the critically endangered status of Australia’s rarest reptile, the Western Swamp Tortoise, by providing information and educational resources."
The Quagga Project "This project, started in 1987, is an attempt by a group of dedicated people in South Africa to bring back an animal from extinction and reintroduce it into reserves in its former habitat."
IUCN Species Action Plans A list of all of the IUCN's species action plans. Most are downloadable as .pdf files for free. There is tonnes of excellent information for the conservation-minded reader.
The Bulletin of the British Ornithologists' Club Volumes 1 to 127 are available for free from the Biodiversity Heritage Library (BHL).
Julian Pender Hume's website Many of his publications are available on his website, most of which pertain to recently extinct species.
Pleistocene Vertebrates of Southwestern USA and Northwestern Mexico by Dr. Arthur H. Harris
FishBase A database of most species of both freshwater and saltwater fish. It is regularly cited by both popular and scientific authors.
Species Files A database with species files on many insect orders (Mantodea, Orthoptera, Phasmida etc.)
Zoonomen An online resource for current ornithological taxonomy. Includes many side notes and clarifications of the correct year of publication etc.
The Endangered Species Act
'Federal Efforts to Ensure Biodiversity: The Endangered Species Act'. (2017). Retrieved from https://lawshelf.com/videos/entry/federal-efforts-to-ensure-biodiversity-the-endangered-species-act [accessed 21 December 2017]
'From Plastic Pollution to Global Warming: Top Environmental Issues We're Facing Today' (n.d.). Retrieved from: https://www.bottlestore.com/environmentalissues [accessed 21 May 2020]
Anabel Lang kindly provided the LawShelf web page about the Endangered Species Act. Thanks to James (sophomore) from the Fairview School Conservation Association for the web page about environmental issues.