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Archives for May 2011

Like moths to a flame

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Matt Walker Matt Walker | 10:01 UK time, Thursday, 26 May 2011

Moths around an electric light blub (image: Dr John Brackenbury / Science Photo Library)

A burning conservation issue? (image: Dr John Brackenbury / Science Photo Library)

Like a literal moth to a flame, insects of all kinds are attracted to light bulbs.

Desperate it seems to fly into the light, they repeatedly thwack themselves on a bulb until, finally, they perish.

Such kamikaze-like death flights occur again and again, in almost every household kitchen, on every porch, around every camp light.

In fact it is such a common behaviour it seems wholly unremarkable.

But remark on it I will due to a report just published by Buglife, a conservation trust that seeks to protect invertebrates.

According to Buglife, the use of artificial light by people is significantly affecting the ecology of a range of invertebrates, including moths, beetles, caddisflies, mayflies, lacewings, aphids, hoverflies, true flies, dragonflies and damselflies, among others.

Artificial light is becoming such a problem that Buglife is imploring us to change our habits, and to be careful about where we place bright lights, think about when we switch them on, and even consider changing the way we install solar panels.

It is an issue I’d like to hear your thoughts on. First to see whether you agree it is a problem. And if so, how you would recommend society goes about addressing it.

Read the rest of this entry

Evolution, sex and dinosaur necks

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Matt Walker Matt Walker | 09:55 UK time, Tuesday, 24 May 2011

Diplodocus (image:Mark Hallet, PaleoArt/SPL)

Diplodocus, perhaps the most famous sauropod (image:Mark Hallet, PaleoArt/SPL)

They are among the largest and most fascinating creatures ever to have walked the Earth.

I’m talking about sauropods, the group of four legged dinosaurs that are almost instantly recognisable due to their long necks, each of which reaches out to a small head, and long tails.

Among the sauropods is the famous Diplodocus, and less well known, but even more remarkable species such as Argentinosaurus, which holds the record for being both the heaviest land animal ever, and the longest.

But what have these giants got to do with sex?

Well scientists are debating what exactly caused these huge reptiles to evolve their huge necks.

A recent theory proposed is that sex, or more accurately sexual selection, was the main driver.

The idea is that down the generations, male sauropods evolved ever longer necks to dominate rivals for the affections of females.

Dinosaurs are long dead, making it harder to test ideas about why certain traits evolved, and what they were adapted for. But evidence can still be brought to bear to analyse the different hypotheses.

For example, for much of the 20th century, sauropods were imagined to be water-loving beasts, which lived or spent much of their time in water, using their long necks as snorkels.

In the 1970s that idea fell into disrepute as multiple lines of evidence, since validated, showed sauropods to be mainly land-going animals.

That then led palaeontologists to imagine that sauropods used their long necks to reach huge amounts of vegetation – enough to yield the energy needed by their huge bodies.

A long neck, the reasoning goes, enabled Argentinosaurus and its ilk to graze plant material from a large “envelope”, from ground grasses to leaves in trees many metres high.

But then along came the sexual selection hypothesis, first proposed in 2006.

It argues that male sauropods that inherited a longer neck, caused by a chance mutation, would be more attractive to females.

The length of their neck would signal their virility and suitability as a sire.

Giraffe (image: Arup Shah / NPL)

Neck thumpers (image: Arup Shah / NPL)

A long neck could also have been used to wrestle competitor males, dominating them, just as male giraffes often joust by “necking" and "head clubbing" one another, with males with the longest necks and heaviest heads tending to win. Galapagos tortoises may also use the length of their necks to establish dominance.

Long necked males should therefore sire more offspring, on average, and pass down the long-necked genes, driving the trait through the population.

Just as palaeontologists argued over whether sauropods were terrestrial or aquatic beasts, they are now debating the merits of whether sexual selection or eating vegetation explains the long neck of the Diplodocus and others.

And the sexual selection idea has just been examined in detail, and dismissed.

Dr Mike Taylor of the University of Bristol and colleagues tested the arguments put forward to support the idea, and found them wanting.

Firstly, they say there is no evidence in the fossil record of a sauropod species that has males with relatively longer necks than females, or visa versa, which would be expected if it was a "sexy" trait.

While is impossible to witness whether extinct dinosaurs “necked” as giraffes do, their fossilised bones suggest they did not – they do not become any thicker to resist the blows, which would be expected, or show any signs of trauma associated with such behaviour.

There are a host of other more technical reasons for why a long neck wasn’t a sexy neck, Taylor and colleagues describe in the Journal of Zoology.

Their arguments are pretty convincing.

Such debates occur more often than you might expect, at least when it comes to sexually selected traits.

Indian peafowl (image: Phillipe Clement / NPL)

An eye for the females? (image: Phillipe Clement / NPL)

For example, there is still no firm agreement as to whether female peacocks find the elaborate trains of male peacocks attractive (length and eyespot number play a role, though precisely what is unclear).

There have also been similar debates about why giraffes have such long necks.

Indeed the proposal that the giraffe evolved its long neck as a sexual signal led to the proposal that sauropods do similar.

But in 2009, that hypothesis finally bit the dust after Professor Graham Mitchell of the University of Wyoming, in Laramie, US, and colleagues put the sexual selection hypothesis to the test by examining 17 male and 21 female giraffes.

They found if long necks were a sexually selected trait, they expected to find a number of things:

Long necks should be more exaggerated in males than females.

They should evolve to be bigger in size more than other parts of a giraffe's body.

They should confer no immediate benefit to survival, and may come at a cost.

Their results didn't support any of these propositions.

This refutation is similar to that by Dr Taylor and his colleagues. Sauropod necks aren’t more exaggerated in males than females, and they aren’t particularly costly.

Dr Taylor’s team make one final point.

There is no example, anywhere, of a type of four-legged animal, of which there are many species, that has evolved a single trait to be sexy. Crabs evolve big claws to show off, some flies evolve giant eye stalks, birds of paradise shake their sexy tail feathers.

But dinosaurs? Not likely it seems.

A sexy neck just didn’t get the reptilian juices flowing. 

Is the giant squid the new giant panda?

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Matt Walker Matt Walker | 09:20 UK time, Friday, 13 May 2011

Illustration from the original edition of Twenty Thousand Leagues Under the Sea depicting a giant squid

Illustration from the original edition of Twenty Thousand Leagues Under the Sea depicting a giant squid

Can a 13-metre long beastie, all tentacles and suckers, be a conservation icon for our time?

Scientists are proposing that the giant squid Architeuthis be emblemised and celebrated to help promote the conservation of marine diversity.

The giant squid would become the giant panda of the seas; a single species that captures the imagination, and stands for the world in which it lives.

It would become a rallying point for those seeking to protect life under the waves, the fish and the whales, the corals and crustaceans, an abundance of marine invertebrates and creatures we perhaps have yet to discover.

It could even become a marketing tool, a brand, a philosophy.

Rather than have to make complex arguments about marine food webs, carrying capacities, life histories and bycatch, people could support the saving of the seas by wearing a giant squid badge, while giant inflatable squids could be blown up at events designed to raise marine conservation funds. Anyone fancy running a marathon in a squid costume trailing eight arms and two 10-metre long tentacles?

It’s a far less ridiculous idea than it sounds.

Many people are already attuned to the fate of marine mammals, galvanised by the whaling debate, whale song soundtracks and the actions of organisations such as Greenpeace. The overfishing crisis gets good air time, and the epic journeys made by sea turtles prick something in the public consciousness.

However, most people aren’t aware that about 92% of marine species are invertebrates – animals that lack backbones. And though estimates vary a lot, there may be anywhere between 178,000 and 10 million such species living beneath the waves.

Even if people are aware these species exist, animals with exoskeletons or shells, such as corals, crabs and clams, tend not to tug at the heart strings.

Not like the giant panda, which has become the conservation icon for land animals.  

The emblem of conservation charity WWF, by the charity’s own admission the panda is recognised worldwide as a symbol of conservation and sustainable development, and is perhaps better known than the work of the organisation itself.

Natural history author Henry Nicholls, who has written extensively about the giant panda’s allure, has recently published a comment piece in the journal Nature highlighting how different conservation organisations have embraced animal emblems.

His piece talks of how the marketing of these emblems has evolved over time, but it’s instructive to read how.

To quote:

Logos began to portray species that did have a clear conservation message. The dodo, the icon of extinction, was a perfect image for the Durrell Wildlife Conservation Trust, founded in 1963 to support Gerald Durrell's pioneering conservation-focused captive work at Jersey Zoo in the Channel Islands. There were also more upbeat emblems. The moving tale of Elsa the lioness (star of Joy Adamson's novel Born Free and its 1966 Hollywood adaptation and memorable soundtrack) made her an exemplary face of the Born Free Foundation, established in 1984 to campaign against zoos and promote conservation in the wild. The RSPB's success in recreating the habitat suitable for breeding avocets in Britain during the 1940s made this species an obvious choice as an emblem.

Hence why marine biologist Angel Guerra of the Institute for Marine Investigation in Vigo, Spain and colleagues now argue that the marine world needs its own emblem.

In the journal Biological Conservation, they lay their reasoning for why it should be the giant squid.

At first glance, this huge invertebrate seems an odd choice.

Adult Architeuthis dux in the wild (image: Dr Tsunemi Kubodera)

A rare glimpse of an adult Architeuthis dux in the wild (image: Dr Tsunemi Kubodera)

We know virtually nothing about it; the first pictures of a live, adult giant squid were only caught on camera in the wild in 2005.

The 30 or so specimens landed to date reveal a huge animal up to 13 metres long with ten arms, two of which are massively elongated. The squid has a large beak which is uses to crush its prey. But we still know little about how it lives.

However, it does fit the requirements of an emblematic species, say Guerra’s team.

The animal that likely inspired the ancient mariners’ myth of the Kraken that appeared out of the deep ocean, the giant squid has long attracted the public’s attention.

It still has the power to awe: people flock to see the few specimens held in museums around the world, and giant squid get a significant amount of press coverage.

Architeuthis may also act as a bellwether for human impacts on the ocean.

As carbon dioxide levels increase in the atmosphere, more dissolves into the oceans, resulting in a fall in pH.

This increase in ocean acidity could make it harder for squid to produce small structures called statoliths which they need for movement and balance. That means more giant squid could float the surface, where they would die. More acidic oceans could also affect squid respiration and embryo development.

Giant squid, Architeuthis sp., modified from an illustration by A.E. Verrill, 1880

Giant squid modified from an illustration by A.E. Verrill, 1880

Although Architeuthis has been found worldwide (677 specimens recorded to date from the southwest Pacific to the northwest Atlantic), it mainly appears in areas with submarine channels or canyons that cut across the continental shelf.

These deep canyons are biodiversity hotpsots, and are vulnerable to deep sea fishing and dredging. Giant squid are also vulnerable to both, as well as pollution and potentially even seismic surveys or sonar.

The logic suggests therefore that if we learn to love, celebrate and protect the giant squid, we could also protect an entire unique marine ecosystem, and all the other more recognisable animals living within.

So is it a reasonable proposition?

Just a small population of reclusive giant pandas have enthralled us for decades now. Yet the species became the emblem of the conservation movement, not because it best represented the issues at stake, but because it was black and white.

As Henry Nicholls recounts in his Nature article:

“In 1961, as the WWF's founders mulled over the choice of their symbol in a plush town house in London's Belgravia, the most important consideration was that it should reproduce well on the organization's letterhead. With colour printing then out of the question for a fledgling charity, this narrowed the options to a shortlist of black-and-white species, and the popular panda emerged.”

So why not too the giant squid?

It isn’t as cuddly-looking as a giant panda.

But this outsized, almost monstrous sea creature of lore is perhaps the more enigmatic, secretive, bizarre and fascinating animal. It may also better represent the ecosystem in which it lives, and the threats to it.

Does it have what it takes for you to fall in love with it, and grant it emblematic status? Would you help save the giant squid, in a bid to save the seas?

Tiddle's law: should we restrict cat ownership to preserve wildlife?

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Matt Walker Matt Walker | 08:30 UK time, Monday, 9 May 2011

Silver Persian cat (image: Andrey)

Cute cat or cuddly menace? (image: Andrey)

Here’s a question for all you cat lovers.

Should there be a limit on the number of cats you are allowed to keep? Say, maybe, just the one per household – a Cat Cap if you like, or a Single Puss Policy?

And should this single cat be registered with the authorities, sterilised, and confined to home, or only let out under curfew? Tiddles must have the right papers, lack testicles, and avoid hanging around the block out of hours - otherwise Tiddles must go.

Oh, and on the few occasions Tiddles is allowed out, he must wear a special collar that will alert mice and birds to his presence, to ensure they don’t become his lunch.

Legislating cat ownership this way sounds pretty heavy handed, draconian even. Would we even need a pet police to enforce the rules?

But I mention them to raise an important issue – to what extent do our domestic pets impact other animals living wild? Is our pet predilection causing a conservation problem, one that we need to address?

The suggestion that it could be, and we should think about restricting or controlling the animals we bring into our homes, appears in a new research paper published by Australian scientists in the journal Biological Conservation.

Michael Calver and colleagues at Murdoch University in Western Australia, and the University of Sydney, argue for why we might consider using the precautionary principle when it comes to cat ownership.

They start by laying out the context.

There is now abundant evidence that feral cats can cause the decline or even elimination of local wildlife. A yet to be published review by ecologist Elsa Bonnaud at the Mediterranean Institute for Ecology and Palaeoecology in France and colleagues suggests they are responsible, at least in part, for 8% of global bird, mammal and reptile extinctions and pose a significant threat to almost 10% of critically endangered birds, mammals and reptiles.

But feral cats are pets no more – and you can’t compare a ranging hungry street cat with a well fed pet that spends most of its time indoors or in its owner’s back garden.

Cat eating a bird (image: Mark Marek Photography ©2007)

Cats may eat millions of wild birds (image: Mark Marek Photography ©2007)

So Calver and colleagues detail what we know about the impact that domestic cats have.

In some urban areas, cats are kept at such artificially high densities that more than 100 can live in any square kilometre.

A number of studies have tried to evaluate how many wild animals these cats kill.

A 2003 study in the journal Mammal Review (view it as a PDF) suggested that cats predate 5 million reptiles and amphibians, 27 million birds and 57 million mammals in the UK each year.

In the US, some estimates say 100 million birds are killed by cats each year (a Forest Service report by Erickson et al in 2005) and “more than a billion small mammals”, according to a study published this year by the American Bird Conservancy (view it as a PDF).

These figures are controversial, and as Calver and colleagues point out, some of them may be exaggerated.

Focusing on the impact pets have on wildlife can also significantly deflect attention from other far more significant causes of wildlife loss, such as habitat destruction.

However, until the debate is resolved, say Calver and colleagues, we should consider adopting the precautionary principle.

That means taking steps to limit the impact pet cats may have on wildlife - in case it turns out that their impact is indeed large.

These steps could include the previously mentioned cat cap that limits owners to two or fewer cats per household, neutering, the use of cat licenses, confining pets and cat curfews, or even complete bans on cat ownership within a kilometre or two of environmentally sensitive areas, particularly those that provide habitat to rare prey species. 

Although they sound draconian, many or all of these measures are already in place (though not at the same time) in different municipalities around the world, often enforced by local councils.

It’s a tricky and controversial topic.

For example, predation-prevention collars, such as the straightforward bell on a cat collar, or a collar that sounds an electronic alarm, can reduce predation of wild animals by more than 50%.

But while statutory neutering of cats may prevent unwanted litters, there is little or no evidence that neutered cats are less accomplished hunters or stray less far when out hunting.

Ultimately, the scientists say, the first step should be to survey citizens and cat owners to see whether they think their cats cause a problem for wildlife, and what if anything should be done about it.

So, what do you think?

Are pet cats a threat to wild animals? And if so, how should their numbers or hunting urges be curbed?

Shooting swans - a modern tale

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Matt Walker Matt Walker | 08:50 UK time, Friday, 6 May 2011

Mute swan (Image: Laurent Geslin / NPL)

Mute swans are entering cygnet season (image: Laurent Geslin / NPL)

According to mythology, a swan will sing beautifully and mournfully just before it dies.

It’s the origin of the phrase “a swan song” – the final gesture before retirement or death.

It’s not true: swans don’t call out this way. But the romantics among us might wish they did, if only to warn us of the nature of the birds' passing.

For newly published research has revealed that swans are still frequently being shot, and in some number.

And they are being shot illegally, it’s important to point out, as swans have been protected by national and international legislation throughout their ranges since the mid 20th Century.

Data has been collected showing how many Bewick’s and whooper swans, two migratory species that overwinter in the UK and the Irish Republic, have been peppered with shotgun pellets.

Let’s talk numbers.

First up, the Bewick’s swan, a large migratory bird that flies into the UK and the Irish Republic each winter from Scandinavia and arctic Russia.

Between the winters of 1970/71 and 2008/09 when the sampling of this species was done, 31.2% of live surveyed birds were found to be carrying shotgun pellets.

For the larger whooper swans which fly in from northwest Europe and Iceland, the sampling was done between 1988/89 and 2007/08.

Of live whooper swans surveyed, 13.6% had been shot at least once in the past and survived.

X ray of gun pellets embedded in a swan (image: Julia Newth/WWT)

X ray of gun pellets embedded in a swan (image: Julia Newth/WWT)

So almost one in three Bewick’s swans, and more than one in eight whooper swans had been fired upon, and hit, at some point in their lives.

These figures were obtained by Julia Newth, Martin Brown and Eileen Rees of the Wildfowl and Wetlands Trust (WWT) at Slimbridge, Gloucestershire, and have just been published in the journal Biological Conservation.

The research team trapped live swans at different sites in the UK and x-rayed their bodies, to reveal the presence of gun shot (in their tissues, not gizzards, confirming they weren’t eaten by the birds).

The data reveals what proportion of sampled swans survived a shooting – it doesn’t say anything about the number of swans that didn’t make it.

“With such high levels of wounding, it follows that many birds are probably killed by shooting,” says the WWT.

Also, swans that survive a shooting aren’t out of the proverbial woods. Research shows swans, geese and ducks that have survived a shooting still tend to die younger, on average, perhaps due to the injury or trauma.

Now let’s talk history.

Swans in the UK once faced a significant threat from another type of lead shot.

When foraging for grit, which the birds use to break down food, they used to inadvertently ingest lead weights favoured by anglers. Strong circumstantial evidence suggested these weights poisoned large numbers of swans.

Since the use of these weights was restricted in 1987, populations of mute swans (which tend to live in the UK year round) have increased significantly.

Whooper swans migrate shorter distances (Image: Mark Payne-Gill / NPL)

Whooper swans migrate shorter distances (Image: Mark Payne-Gill / NPL)

That threat is now receding, as to a degree is the threat from hunters with guns, perhaps due to the influence of legislation. Bewick’s and whooper swans have long been protected from hunting throughout their migratory ranges (since 1885 in Iceland, 1954 in the UK, 1964 in Russia and 1976 in the Irish Republic).

For example, the WWT’s data shows that, over time, the proportion of sampled Bewick’s swans found with shot in their bodies has declined, from a peak of 39% in the 1980s to almost 23% in the 2000s.

But that suggests that, even today, around one in four living Bewick’s swans arriving on our shores has been shot and survived.

Also, there is no such decline in the proportion of whooper swans suffering the same: 14% of those x-rayed in the late 1980s contained shot compared to 13% in the past decade.   

It is not clear where the swans were shot. There is evidence they are shot throughout their ranges: Bewick’s swans have been found shot dead in Estonia and Russia while shot whooper swans have been recovered in Iceland, France and the Irish Republic.

A higher proportion of Bewick’s swans are thought to be shot due to the fact they migrate longer distances, with more of it occurring over land, whereas the whooper swans’ shorter migration is mainly over open ocean.

Map of Bewick's swan migration (Image: Robinson et al 2004)

Map of Bewick's swan migration (Image: Robinson et al 2004)

But they are clearly being shot in the UK too.

A number of adult swans had a greater number of pellets in their bodies when sampled a second time in the same winter in the UK, showing they had been shot in this country. News organisations have also reported swans being shot in Somerset, Nottinghamshire
and North Tyneside.

Swans have always been poached. They also become entangled in fishing gear, can hit power lines and be affected by freshwater pollution.

But perhaps these pressures are reasons to take more notice of the fact that swans are still being shot, illegally, in relatively large numbers.

Worldwide, mute swan populations are healthy, and are growing in the UK. Cygnet season is upon us, as over the next six weeks baby mute swans begin hatching in wetlands around the UK. The arrival of these cygnets should ensure another generation of one of Britain’s largest and most impressive birds.

Globally, whooper swan numbers appear stable. However, Bewick’s swan numbers have fallen steadily since the mid-1990s. Doing more to enforce the hunting bans is one way to help arrest their decline.

A swan song may be a mythical act. But shooting swans is a very real gesture, one that the WWT feels compelled to make a noise about.

Trampling the great outdoors

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Matt Walker Matt Walker | 12:48 UK time, Wednesday, 4 May 2011

Man climbing on mountain

Does a pioneering spirit come at a cost? (Image: Leon Brooks)

What better way to embrace nature than to explore the great outdoors?

Better still, make a hobby out of it: go mountain biking, hiking, skiing or climbing – anything to keep fit, breathe fresh air and wonder at the world around you.

It sounds idyllic, but for the natural world, it could be anything but.

By exploring the great outdoors, we may be trashing the great outdoors.

How you might ask, given that cyclists, ramblers, alpine skiers and climbers tend to be among the most conservation-minded of people, given how much time they spend embracing the wilderness?

Well it turns out that even the most innocuous activity can, if done often enough, have a significant impact on wildlife.

Today researchers have published a study into the effects that climbing has on mountain plants, particularly the yellow whitlowgrass (Draba aizoides) that lives on limestone cliffs where it forms cushion-like rosettes.

The whitlowgrass is already rare, with its last strongholds in the northern Franconian Jura and the Swabian Alb – which also happen to be two of Germany’s most important climbing areas.

Yellow whitlowgrass (Draba aizoides)

Draba aizoides © 2005 Dr. Amadej Trnkoczy

Fewer whitlowgrasses grow on cliffs that have been regularly climbed for the past 50 years, than on cliffs unclimbed, Frank Vogler and Christoph Reisch report in the Journal of Applied Ecology.

Climbers also knock enough of the plants off the cliffs to change the structure of the plant’s population – on climbed cliffs, the plants were smaller as well as fewer in number.

The yellow whitlowgrass could be a unique case, you might argue.

That’s true, but the researchers studied D. aizoides because it is representative of many other typical central European cliff plants.

Other studies show similar effects.

Climbing has been found to significantly reduce species richness and diversity, with pristine cliffs being home to twice the number of plants than climbed cliffs. While endangering rare species, rock climbing has also been found to lead to an increase in more alien, invasive plants.

These studies potentially give rock climbers a bad press. Fewer in number than ramblers, cyclists or skiers, they also, by definition, tend to roam less far, meaning their overall impact is probably less.

But if climbers can impact the ecology of their chosen arena then what of these other pursuits?

In the past few years, researchers have found that outdoor winter sports (skiing, snowboarding, and snowshoeing) can stress out the surrounding wildlife.

Black grouse  © Markus Varesvuo)

Black grouse (image: Markus Varesvuo / NPL)

One in particular found that numbers of black grouse fell by a third in areas populated by ski lifts and skiers. Alpine black grouse are an indicator species of the health of the timberline ecosystem, the favoured habitat for outdoor winter sports in the European Alps. Yet wintersportsmen and women deterred grouse to a greater extent than hunters, the study found.

Other studies show that people visiting the countryside can have an impact on birds of prey, and people visiting coastal areas can impact seabirds.

Of course, this focuses the attention on the negative impacts of outdoor pursuits.

They have positive impacts too – rambler and mountain bike trails are often sensitively laid and the demand for recreational activities can lead to a better stewardship of the surrounding environment.

The same studies that show an impact on seabirds suggest that birdwatching can be compatible with healthy seabird colonies if properly managed.

The truth is that overall, little is known about whether outdoor pursuits have a positive or negative impact on the great outdoors – the science hasn’t been done, and there are complex factors involved (not least understanding the more subtle effects on animal behaviour of people enjoying outdoor pursuits nearby).

In one sense the solution is simple, follow the precautionary principle and ensure that enough areas are left pristine and out of bounds to outdoor explorers. Create properly managed reserves, trails, ski runs and watching posts, and make the rest off limits.

But as populations increase in size, and recreational outdoor leisure activities continue to grow in popularity (as they have since the 1960s), then this will become a harder balance to strike.

Do we deny people access to great swathes of wilderness, risking that they may also care less about it, and leave it vulnerable to more destructive forces such as commercial development? Do we blunt the adventurous pioneer spirit?

Or do we sharpen it? Do we go out and explore the great outdoors, absorb its majesty, potentially trampling it underfoot as we do so?

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