Syllabus Edition
First teaching 2015
Last exams 2025
Extinct, Critically Endangered & Improving Species (DP IB Environmental Systems & Societies (ESS))
Revision Note
Written by: Alistair Marjot
Reviewed by: Bridgette Barrett
Extinct, Critically Endangered & Improving Species
Extinct Species
James St. John, CC BY 2.5, via Wikimedia Commons
The passenger pigeon is now only seen in museums
Passenger Pigeon (Ectopistes migratorius):
The Passenger pigeon was once one of the most abundant bird species in North America, with flocks numbering in the billions
However, due to overhunting and habitat destruction, the passenger pigeon went extinct in the early 20th century
The hunting of these birds for meat, as well as the destruction of their forest habitats, led to a sharp decline in their numbers
By the late 1800s, the species was in serious decline, and despite some attempts at conservation, it went extinct in 1914
Tasmanian Tiger (Thylacinus cynocephalus):
The Tasmanian tiger, also known as the thylacine, was a carnivorous marsupial that once inhabited the Australian island of Tasmania
Human activity such as hunting, habitat loss, and disease transmission by introduced species caused their population to decline, and the last known Tasmanian tiger died in captivity in 1936, marking the extinction of the species
Critically Endangered Species
The sumatran orangutan is critically endangered
Sumatran Orangutan (Pongo abelii):
The Sumatran orangutan is one of three species of orangutan and is found only on the Indonesian island of Sumatra
Habitat destruction and fragmentation due to logging, conversion of forests to agriculture, and infrastructure development have been the primary causes of its decline
In addition, illegal hunting and capture of orangutans for the pet trade have also contributed to their decline
The Sumatran orangutan is now critically endangered, with only around 14,000 individuals remaining in the wild
Black rhinoceros (Diceros bicornis):
The black rhinoceros is a large mammal native to Africa and is critically endangered due to poaching for their horns, habitat loss, and civil unrest in the countries of their range
Their population has declined by over 90% since the 1960s, and there are currently only around 5,500 individuals remaining in the wild
Conservation efforts such as anti-poaching patrols, habitat restoration, and captive breeding programs are underway to try to save this species from extinction
An Improving Species
Becker1999 from Grove City, OH, CC BY 2.0 by/2.0 via Wikimedia Commons
The southern white rhino is a success story in conversation having been brought back from the brink of extinction
Southern white rhinoceros (Ceratotherium simum):
The Southern white rhinoceros was once on the brink of extinction due to poaching for their horns, with only a handful of individuals surviving in the wild in South Africa in the early 20th century
However, conservation efforts including increased law enforcement, habitat protection, and captive breeding programs have helped their population recover to over 18,000 individuals today
While they are still threatened by poaching and habitat loss, the Southern white rhinoceros' conservation status has greatly improved thanks to human intervention
Bald eagle (Haliaeetus leucocephalus):
The bald eagle is a bird of prey native to North America and was once on the brink of extinction due to habitat destruction, hunting, and pesticide use, which caused eggshell thinning and reproductive failure
Conservation efforts such as habitat protection, captive breeding programs, and the banning of harmful pesticides like DDT have helped their population recover from less than 500 pairs in the 1960s to over 10,000 pairs today
The bald eagle's conservation status has greatly improved thanks to human intervention
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