Extinction theory flipped: humans can save even tiny populations
Scientists had all but given up on species with populations below 50 – but a new study says a little human help can pull Earth’s creatures great and small back from the brink of extinction
READING LEVEL: ORANGE
What do you think is an alarming number when it comes to measuring the population decline in endangered* species?
Scientists previously believed that once the numbers dropped to or below 50, extinction was inevitable*, because the population would be too small for healthy reproduction and successful recovery.
But an international study has flipped that theory, delivering some good news: Australian scientists say a little human help can still save these tiny populations from extinction.
UK and Australian researchers at the Zoological Society of London and Monash University studied 141 bird and mammal species that were on the brink of extinction. These animals had a population of less than 50 in the wild since 1950 and their conservation* history was sufficiently tracked.
The team found that “even in critically small populations,” there was a big chance of recovery with targeted conservation efforts. Their findings were published in the Proceedings of The Royal Society B.
Monash School of Biological Sciences and study co-author Professor Rohan Clarke said the results made a strong case against losing hope for species with a really low surviving population.
“Abandoning critically endangered species because their numbers look too low is a mistake,”
Prof Clarke said.
“While genetic* risks are real, our history shows that human intervention works. Investing in active, science-backed management isn’t futile*; rather, it’s the very thing that saves a species from disappearing forever.”
Researchers believe that a combination of reducing threats and directly managing a species’ population would have the highest rate of success in rescuing them from extinction.
The Australian Lord Howe woodhen was one example. The population of the previously endangered bird grew from a mere 23 birds in the late 1970s to more than 1600 today.
RESEARCH SCOPE
This was an observational study*, meaning researchers tracked and studied the history of conservation efforts made to rescue these animals.
Of the 141 species studied, they found that 51 had received direct conservation actions including control of invasive predators* and restoration of habitats*.
This group had also been brought into safe sanctuaries and released into safe wilderness areas after successful captive breeding*.
Thanks to all this human support, 61 per cent of them had recovered to at least 100 individual animals.
About 51 other species that had not received any direct support and human help sadly went extinct. Only two per cent of them survived to grow to at least 100 individuals unaided.
Monash University School of Biological Sciences researcher and study lead author Dr Donal Smith said their findings renewed hope for global biodiversity*, a sense of hope backed by scientific evidence.
“For decades, conservation decisions have been influenced by the idea that once a
population drops below a certain threshold*, recovery is severely inhibited* by smallness itself, due to genetic or demographic* factors,” Dr Smith said.
“Our work shows that population size alone shouldn’t determine whether we give up on a
species. When we actively tackle the external pressures driving their decline and directly
support their numbers, small populations show a striking capability* to recover.”
The findings come as a timely ray of hope after the latest World Wildlife Fund report on Australia’s native animal population was released last month.
70 PER CENT DOWN: NATIVE ANIMALS POPULATION
Numbers of some of Australia’s rarest animals have fallen by more than 70 per cent in the past five years, the critical global report card has found, while beloved African and Asian animals such as tigers and southern African elephants have begun to bounce back.
The WWF’s Living Planet Report 2026, which surveyed population trends among 5790 species, found steep falls in the number of gentoo penguins on Australia’s Macquarie Island, as well as the lemuroid and green ringtail possums in the nation’s north.
James Cook University ecologist Dr Alejandro de la Fuente said populations of lemuroid and green ringtail possums had declined by as much as 70 per cent across Australia’s tropical regions since the ‘90s.
“At the warmer, lower edges of the mountains, populations haven’t just declined, they’ve vanished,” Dr de la Fuente said.
“The surprise was that two very similar possums, living in the same forests, are declining due to different processes, both driven by climate change.
“When heat stress lasts more than about five hours without access to water, green ringtail possums overheat and dehydrate, and survival drops. When nights are too hot, lemuroid ringtail possums can’t forage safely.”
Dr de la Fuente said “the window is narrow” to help protect the possums “still hanging on”, including by providing water in the late-dry season.
“We can buy these species time, but we can’t buy them a new climate,” he said.
“These are ancient, irreplaceable animals, found nowhere else on Earth, and we’re the last generation with a chance to keep them.”
TIME TO CHOOSE HOPE
WWF warned the species, many of which are close to becoming threatened, faced habitat loss, over-exploitation*, climate change, and population decline, factors advocates said were driven by “broader systemic failures across the food, energy, and finance systems”.
However, the WWF report also found half of the populations surveyed worldwide were stable or increasing in size, with the size of the downward trends dragging down the average.
Those on the up included the widely overfished bluefin tuna – the Pacific population of which fell to as low as two per cent of unfished levels. Species of tiger and southern African elephants, while remaining endangered, had increased in population in some locations.
Humpback whales, once subject to extensive whaling, had skyrocketed since the 1960s from 200-500 animals to as many as 60,000, including in Hervey Bay in southern Queensland.
WWF Australia chief executive Dermot O’Gorman said while nature was “under pressure … the lesson for our generation is clear”.
“We cannot solve today’s challenges with the same scarcity* mindset that helped create them,” he said.
Mr O’Gorman said success found in the report should “give us confidence”.
“At a time when many people are anxious about the future, the answer is not to retreat into fear. Now is the time to choose hope, ambition and action,” he said.
“We know what is driving nature loss, we know much of what works, and we have today all the solutions at hand to build regenerative* food, energy and finance systems that work for both people and nature.”
POLL
GLOSSARY
- endangered: a plant or animal that is at risk of extinction/disappearing from earth forever
- inevitable: certain to happen, cannot be avoided or prevented
- conservation: the act of protecting and preserving wildlife, plants, and natural resources
- genetic: relating to genes or the traits passed down from parents to their offspring
- futile: having no useful result or point, completely pointless/useless
- observational study: research where scientists watch and monitor subjects in their natural surroundings without interfering
- invasive predators: non-native animals that hunt and threaten local wildlife in an area
- restoration of habitats: rebuilding and repairing damaged natural environments for wild plants and animals
- captive breeding: wild animals reproducing in controlled settings like zoos to help save their species
- biodiversity: the variety of all living plants, animals, and organisms in an environment
- threshold: the limit or point at which something starts to happen or change
- inhibited: held back or prevented from growing, moving, or expressing freely
- demographic: relating to specific characteristics of a population like age or group size
- capability: the power, skill, or ability to do something
- over-exploitation: using up natural resources or species too quickly before they can recover
- scarcity: having a shortage or not enough of something
- regenerative food: crops grown using farming methods that restore the soil and help the environment
EXTRA READING
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Tiny Fijian bee faces extinction
Bilby breeding a stunning success
QUICK QUIZ
- What did the researchers find after studying 141 species?
- What happened to Lord Howe woodhen in the 1970s?
- What can save animals on the brink of extinction?
- How did the Humpback whale population change since 1960s?
- What did the WWF report find?
LISTEN TO THIS STORY
CLASSROOM ACTIVITIES
1. How to Choose Hope?
‘Time to Choose Hope.’ Create a list of activities that you and your class or school could do to follow and be inspired by this idea.
Time: Spend at least 30 minutes on this activity.
Curriculum Links: English, Health and Physical Education, Personal and Social Capability
2. Extension
Write a new list of Guidelines, or rules, about how best to manage critically endangered species. Use the information from the story to help you. Next to each rule, write sentences explaining why this rule is important and how it will help.
Time: Spend at least 25 minutes on this activity
Curriculum Links: English, Science
VCOP ACTIVITY
I spy nouns
Nouns are places, names (of people and objects), and time (months or days of the week).
How many nouns can you find in the article?
Can you sort them into places, names and time?
Pick three nouns and add an adjective (describing word) to the nouns.