The annals of conservationWhy is animal conservation important? Animal conservation is important, because animals are the only mechanism to create biodiversity, which is the mechanism that creates a habitable planet for humans. Without animals, the energy from today’s plants (algae, trees, flowers etc) will eventually reach the atmosphere and ocean, much of it as carbon. The quantity of this plant-based waste is so More science are filled with graphs of species decline but how long does it take for successful wildlife recovery? It’s easy to measure the negative impact we’ve had on wildlife because it has been swift, short and heavily observed. It’s harder to fathom recovery potential as there are fewer documented success stories. The other question is, why does it matter? What is wildlife for? If we knew the answer to this, maybe we would set more ambitious targets.

Arabian Oryx. Drawing, Simon Mustoe. — Hunting of the Arabian Oryx doomed this majestic animal to extinction in the wild by 1972. It’s taken 40 years of sustained conservation action to bring the wild population back to over 1,200 individuals. War, modern weapons and hunting present significant barriers to the species’ recovery into former ranges. Drawing, Simon Mustoe.

Table of Contents

How long does it take to double a population?

Here are a dozen examples of successful wildlife recovery for a range of animals that I found online. There are many more but these are enough to illustrate a point. The results broadly show that a doubling of overall animal populations takes on average, about ten years – though this varies enormously based on the animal and its situation. The trend we see in the graphs below is called an ‘exponential’ curve and living in a pandemic has taught us a bit about how these function(Of an ecosystem). A subset of ecosystem processes and structures, where the ecosystem does something that provides an ecosystem service of value to people. More What we’re seeing here is the foot of the curve, before the rates of increase accelerates.

Successful wildlife recovery. Average population increase for 12 species. — Average recovery rate per year, based on the real population data. The vertical lines are a measure of the variation. They don’t overlap between year 1 and 12, which indicates that the difference is statistically significant.

Successful wildlife recovery. Trendlines fitted to species population increases for 12 animals. — I’ve fitted a trendline to each of the species and you can see the variation increases in year 12 as the lines spread apart. For example, Green Turtles (bottom line) recover quite slowly whereas Californian Condor (top line) can recover faster. The red line is the average.

Lessons from a pandemic

If one thing, the pandemic has taught us a lesson in the influence of exponential growth on animal populations. Before COVID-19 few of us had lived the math. The virus grows at an exponential rate and like all lifeforms, starts slow and then accelerates before eventually flattening off. It takes a lot of effort to get from one state to another.

We can kill off wildlife populations fast by hunting or disturbing critical habitat, especially when their numbers are very small. In an exponential setting, the further you are along the long-tail of the curve, the harder it is to get back and wild animals breed a lot more slowly than a virus.

This is the infections graph from New York, from the Worldometers site. The first wave follows a classic exponential growth, starting slowly at the foot of the curve, then accelerating to peak at around 10,000 cases within about 30 days. With lockdowns, it took about 90 days for the virus effect to decline to about 700 a day.

Successful wildlife recovery may take 30 years. Short-tailed Shearwater. — If we apply the ‘average’ recovery rates for other species, it could take over 30 years for Short-tailed Shearwaters to recover. That assumes they are reintroduced and existing threats are removed. That may seem hard to believe, except even today, there are populations of over a million birds on small conservation headlands in Victoria.

Short-tailed Shearwaters have declined from about 26 million in 1970 to 13 million today. In 1798, Captain Flinders counted a flock which he estimated to be 150 million and European hunters wiped out 80% of nesting birds on islands in Bass Strait by the 1930s. The original population might have been 280 million birds at the start of the 19th century. If all barriers to successful wildlife recovery are removed, Short-tailed Shearwater could take 30 or more years to get back to pre-hunting levels. However, I have not flattened the curve and in reality, much of its past habitat may not be available any more due to housing developments, golf courses or other species taking over the empty habitat.

Barriers to successful wildlife recovery

Australia’s east coast Humpback Whales are an example of what animals can do when you remove threats. In this case, whaling ended in 1978 allowing them to recover naturally and over forty years, the population has risen ten-fold, approaching pre-whaling levels.

Species on land aren’t as fortunate and often need a helping hand. Increase in wild populations of Californian Condor and Arabian Oryx are both the result of captive-bred animals being released back into the wild. For many animals, their populations are fragmented and natural dispersal is slow. Animals don’t just randomly move to a new location, as they lack the cultural knowledge to survive. Mostly, they return to the same places to raise their own young.

The reality is, to ensure speedy outcomes, we are going to need to intervene to redistribute and protect wildlife across whole continents. For this, the world needs to buy into the idea of conserving and valuing wildlife but there are challenges to overcome, not least impacts on our existing food systems. To date, the challenges of reintroduction have been insurmountable, especially for the megafaunaThe largest animals that represent the top of the trophic pyramid. These are the final building blocks in ecosystem structures for maximum entropy production. Megafauna can be measured at any spatial scale. The largest animal that ever lived on Earth is the Blue Whale. In a grassland, spiders could be considered megafauna The term is generally reserved for animals larger More that we need the most.

The recovery of Red Kites in Scotland has been far slower than expected due to illegal killing and Californian Condors are being seriously impacted by poisoning from lead-based ammunition. A fifth of the European Beavers in Scotland are already being killed by law and they’ve only just been introduced! The Red Wolf population in the US (left) has declined by 50% since 2012, due to political pressure to stop reintroductions and abandon conservation of the species [2].

The Living Planet Index and ‘bending the curve’

The Living Planet Index measures trends in over 14,700 species of mammals, birds, reptiles, amphibians and fish across the world. By 2020 and at current rates of decline, the per cent change is expected to be almost three-quarters. Again, you can see the exponential decline in the curves in the figure from Leclère et al. (2020) below. Getting out of this and back to a historical abundance is going to take the rest of the century and a commitment to altering our land use and making it nature-positive.

The Living Planet indices between 1970 and 2012 — Trends in the Living Planet indices between 1970 and 2012, with 95 per cent confidence limits Positive number means increase, negative means decline (WWF, ZSL, 2016). *Percentage change is from 1970 to 2009 **Percentage change is from 1970 to 2020.

Successful wildlife recovery — A downward sloping line showing wildlife declines splits into three alternative trajectories, where biodiversityWhat is the definition of biodiversity? When we ask, what is the definition of biodiversity? It depends on what we want to do with it. The term is widely and commonly misused, leading to significant misinterpretation of the importance of how animals function on Earth and why they matter a great deal, to human survival. Here I will try to More increases, plateaus and crashes by 2050. Leclère et al. (2020)

It’s not just about the number of animals though. No animal (including human) exists in isolation and the cascading effects of extinction amplify ecosystem damage and economic by loss ten times. In fact, only half of the world’s animals are declining and that’s most extreme in only one in twenty of those species. But decline in their abundance creates a domino-effect. The good news is, the capacity to bounce back is there if we can give animals the room to reconnect ecosystemsHow ecosystems function An ecosystem is a community of lifeforms that interact in such an optimal way that how ecosystems function best, is when all components (including humans and other animals) can persist and live alongside each other for the longest time possible. Ecosystems are fuelled by the energy created by plants (primary producers) that convert the Sun's heat energy More. But for that, we need to learn to be more hands-off and accepting of wildlife.

How to beat nature’s yielding force

EcosystemsHow ecosystems function An ecosystem is a community of lifeforms that interact in such an optimal way that how ecosystems function best, is when all components (including humans and other…

Changing human values key to successful wildlife recovery

Predicting recovery potential is difficult. It’s even harder to implement as we are dealing with different populations, declines and threats to half of all wildlife. Every species has its own peculiar life history and local conditions affect recovery, often differing wildly across populations. For the worst affected species, where declines might be 90% or more, we may be looking at thirty years . For animals that are verge of extinction, it may take longer.

If we can alter our global farming systems and learn to value wildlife as part of ecosystems and human life support, then it will take the rest of the century to rebuild ‘nature’ That’s assuming we get climate change under control first.

Not to forget though, that it’s not just a case of rebuilding populations. It is likely to take hundreds, if not thousands more years, to recreate cultural connections with the landscape, sufficient to stabilise our climate and food security once more. Once we’ve rebuilt wildlife populations we are going to have to look after them.

In this recent article, I identified three recovery mechanisms: biological, cultural and genetic, with time-scales of 100 years, 10,000 years and 10 million years – the point being that we might only have about 30 years left to avoid the 10,000 year penalty and perhaps as few as a hundred or so years to avoid the 10 million year penalty. Restoring wildlife populations is the only one we can influence on a reasonable time scale.

How many years to restore the planet’s ecosystems?

Summary How many years will it take to restore the planet’s ecosystemsHow ecosystems function An ecosystem is a community of lifeforms that interact in such an optimal way that how…

Instead of looking at animals as commodities, we need to start thinking more holistically, about animals as ecosystem drivers. The value we place on stable functioning systems is what we call biodiversity and it is essential everywhere animals (including humans) live. Rather than tying ourselves to specific targets, we need to accept the need to restore wildlife populations and embrace uncertainty, in the effort to create a more habitable Earth. The good news is that we still have time, as other wildlife is abundant-enough to just keep things under control if we start rebuilding today. We’re also seeing an encouraging uptick in the involvement of local communities in restoration of nature. Getting involved and supporting work in your local area is among the best thing you can do to assist global action.

Thank you to Reddit user u/7LeagueBoots for suggested amendments.

Spotlight

Saiga Antelope conservation

Saiga Antelope Population — Image from Frankfurt Zoological Society.

Saiga Antelopes populations in Betpak Dala, Kazhakstan. Thanks to conservation efforts, the species is beginning to recover. Due to hunting, it took just 10 years for the population to collapse by 95% in the 1990s and a second collapse happened in 2000, possibly due to disease. At that time, the Kazhakstan numbers fell to 15,000 animals. Today, that population is thought to have bounced back to 842,000 and has even doubled in as few as two years. The Saiga Antelope is a species whose population is sensitive to large fluctuations in numbers both naturally and due to human impact. Its survival is testament to the hard work and commitment of countries throughout its range.

Approach and references for species population data

I chose to look at recovery of a dozen populations beginning with at least 50 individuals, though starting populations for some species were much higher (Whooping Crane = 200; Piping Plover = 540; Humpback Whale (Australian East Coast) = 3,200; Red Kite (Wales) = 760; Green Turtle (US coasts) = 500). It’s difficult to find examples with these data consistently beyond about a dozen years. That said, I could investigate this a lot more deeply but this is sufficient to illustrate the point. The results help answer the question, how long will it take to rebuild wildlife populations?

Successful wildlife recovery takes time. But it’s our quickest hope