Longstanding questions about how migratory animals navigate are being answered through the study of eye molecules and the quantum realm.

By Gareth Willmer

Grey-brown bogong moths may not be much to look at, but every year they perform a nocturnal journey worthy of attention. Billions of them fly as many as 1 000 kilometres from plains in eastern Australia to mountain caves to escape the summer heat.

Arriving in late September from their breeding grounds, up to 17 000 moths pack each square metre of cave wall and lie in a dormant state in a southeast mountain range known as the Australian Alps.

Extra sense

‘It usually looks like the scales of a fish if you go into these caves during the summer,’ said Professor Eric Warrant, a biologist at Lund University in Sweden. ‘It’s absolutely amazing.’

In autumn, the moths fly back to mate, lay eggs and die. Their progeny repeat the voyage without any experience of it – a feat that has long puzzled researchers.

While it has been known that insects, birds, turtles and fish can navigate using the Earth’s magnetic field, the specific mechanisms employed to activate this “sixth sense” have remained mysterious. So too has the connection with other potential sensory cues.

Greater knowledge in this area could bolster conservations efforts and help stem widespread losses in biodiversity amid warnings from scientists that the world is facing a sixth mass extinction.

In 2019, the bogong-moth population suffered a 99.5% collapse as a result of drought. Although the numbers have risen since, they’re still well down compared with before.

Crucial species

The moths are crucial for plant life that they pollinate and for wildlife that depends on them for food. One such animal is the critically endangered mountain pygmy possum.

‘The bogong month is a keystone species in the alpine ecosystem, so their survival is critical,’ said Warrant.

He led a project that received EU funding to uncover some of the secrets of the bogong moths’ navigating abilities. Called MagneticMoth, the project ended in August 2023 after six years.

Warrant’s team tethered migrating bogong moths in an outdoor flight simulator. In doing so, the researchers confirmed that the moths did indeed use the Earth’s magnetic field to navigate.

The next task was to find out how the moths do this and where the mechanisms responsible are located.

The team investigated molecules called cryptochromes. In birds, evidence suggests that cryptochrome in the eyes may enable them to “see” magnetic fields.

While the project’s genetic analysis has yet to yield final results, Warrant believes they will prove that cryptochromes are responsible for magnetic sensing in bogong moths.

Starry surprise

The team also made discoveries that took matters in new directions.

‘We found out a few other things that I think are actually even more exciting than this sensing,’ said Warrant.

One is that bogong moths use the stars – in addition to the Earth’s magnetic field – to navigate. In the laboratory, their brain cells responded to the rotation of a projected night sky.

Warrant said the ability to use night-sky cues to navigate in a specific compass direction was previously known only in humans and in some species of nocturnally migrating birds. The moths possess it while having a much smaller head.

‘The moths seem able to travel in their inherited migratory direction under a starry night sky even if we remove Earth’s magnetic field,’ Warrant said. ‘If you have this tiny insect with a brain a tenth the volume of a grain of rice and eyes smaller than a pinhead, that they can do this is surprising.’

The finding suggests bogong moths may also be using a “hierarchy” of cues to navigate, with the ability to rely on different ones when others aren’t available. Pending further research, Warrant suspects the stars may even be the dominant cue.

Quantum ideas

Understanding how migratory birds use Earth’s magnetic field has also been a challenge with implication for conservation efforts.

That’s partly because the magnetic interactions at play have seemed too weak to trigger the required chemical reactions.

But attention is now turning to one possible explanation: atomic and subatomic “quantum” scales, at which behaviour of matter doesn’t follow typical rules.

‘There’s a quantum-mechanical mechanism by which such weak magnetic interactions can affect chemistry,’ said Professor Peter Hore, a chemist at the University of Oxford in the UK.

He’s pursuing this avenue as co-coordinator of an EU-funded project called QuantumBirds. It runs for six years until the end of March 2025.

Blue light

As with bogong moths, the focus is on cryptochromes serving as a compass for birds to navigate during migration.

Derived from the Greek for “hidden colour”, cryptochromes are molecules sensitive to blue light in certain animals and thought to be involved in magnetic-field sensing in a number of species.

‘Migratory birds have at least six different cryptochromes in their eyes,’ said Hore. ‘We needed to work out which was most likely to have a magnetic-sensing function.’

The team settled on a candidate called cryptochrome 4a – Cry4a – for several reasons including changing levels of the protein in night-migratory European robins.

‘Cryptochrome 4a shows a seasonal variation, with higher levels in the spring and autumn,’ said Hore. ‘That would be consistent with migration.’

With Cry4a in lab cultures, the QuantumBirds team found evidence that the molecule was indeed magnetically sensitive – and more so than the same proteins in non-migratory pigeons and chickens.

While testing Cry4a in live robins would be needed to confirm this as the mechanism, the results are promising, according to Hore.

‘This cryptochrome seems to have the right properties to be the basis of the birds’ magnetic compass,’ he said.

Homing instinct

Understanding how migratory birds navigate could be key to future conservation, particularly given that it is difficult to relocate them because of an instinct they have to fly back to their habitat, according to Hore.

‘If we could understand the mechanisms they use to navigate, maybe we could fool them into thinking they want to stay where we’ve put them,’ he said.

For his part, Warrant at Lund University said greater knowledge about how creatures including bogong moths navigate could lead to the development of alternative navigation systems to GPS for people to use.

Understanding the homing instincts of moths – coupled with the pivotal role that they play in the ecosystem – is yet another reason to ensure their protection.

‘Raising awareness that even a humble insect is worth saving is an important step in the right direction,’ Warrant said.

Research in this article was funded by the EU.This article was originally published in Horizon, the EU Research and Innovation Magazine.

A shift in diets is central to tackling obesity and climate change, according to Eric Lambin, a member of the European Commission’s Group of Chief Scientific Advisors.

By HORIZON STAFF

Human health is inextricably linked to food and the environment. The world, including Europe, faces emergencies on all three fronts.

The current food system is damaging people’s health by contributing to obesity and destroying the environment by, among other things, causing greenhouse-gas emissions and biodiversity loss.

Given the high stakes and challenges, Horizon Magazine plans a five-part series of articles over the remainder of 2023 on “sustainable food”. The aim is to highlight the promises of bringing about fundamental improvements in this area including with the help of research and innovation.

Today’s start of the series sets the stage by featuring an interview with Eric Lambin, a professor of geography and sustainability science at the Université catholique de Louvain in Belgium.

Lambin is also a member of the European Commission’s Group of Chief Scientific Advisors (GCSA), which produced a June 2023 Scientific Opinion entitled “Towards Sustainable Food Consumption”. The opinion was requested by European Commissioner for Health and Food Safety Stella Kyriakides.

The ensuing articles in the series will focus on dietary shifts, urban food systems, the microbiome and the role of legislation.

1. Food, health and sustainability have been linked for thousands of years. Why should people today pay any particular attention to this area?

We are now facing a public health crisis – with widespread overweight, obesity and malnutrition issues – and a global environmental crisis.

Today, livestock accounts for more than 14% of human-induced greenhouse-gas emissions, which is more than the emissions from all the world’s cars and trucks. Production of meat – especially beef – drives climate change directly by emitting methane and indirectly by converting tropical forests for pastures and animal-feed production. Forest conversion not only adds to emissions but also causes biodiversity loss. We imagine most of the green fields we drive past are crops for humans to eat, whereas in fact two-thirds of the world’s agricultural lands are grazing lands and 40% of the world’s cropland is for animal feed.

Our Scientific Opinion calls for system-wide changes to correct this.

2. What would a more sustainable food system mean concretely?

For most Europeans, diets should be more plant-based as they are often too high in meat and dairy products, which have much higher environmental footprints than plant-based foods.

To shift towards a healthier and more sustainable diet, it is recommended to consume more legumes, fruits, vegetables, nuts and seeds and less meat – especially red and processed meat – fewer foods rich in saturated fat, salt and sugar, fewer snacks with poor nutritional qualities and fewer ultra-processed foods, sugary drinks and alcoholic drinks.

For animal-based foods, we should prioritise the consumption of sustainably sourced fish and seafood.

We also need to reduce food waste to minimise the unnecessary use of resources for growing, harvesting, transporting and packaging food that ends up in landfills.

3. What role can the EU play to ensure that food is healthier and greener?

The Scientific Opinion recommends that policy measures aiming to change consumer behaviour should focus on the whole “food environment”. That is anywhere where people obtain, eat and discuss their food.

So policy measures should address not only consumers but also food providers, producers, manufacturers, distributors and retailers. The competences needed to accelerate a transition towards more sustainable and healthy diets are distributed at all levels of governance, from the EU to Member States, regions and municipalities.

The EU can provide guidelines, adjust subsidies, develop labels, expand its current carbon-pricing scheme, among other things, and encourage Member States to act at their level.

4. What is the GCSA recommending in terms of EU action in this field?

The EU should adopt a mix of complementary policies based on pricing, information and regulation.

Healthy and sustainable diets should be the easiest and most affordable choice. EU Member States should consider new incentives including lower value-added tax on fruits and vegetables as well as disincentives such as meat and sugar taxes.

The provision of trusted information about the environmental and health impacts of different foods facilitates healthy and sustainable decision-making by consumers. This is about such things as food literacy, national dietary guidelines and front-of-pack labels.

New policy measures should also make healthy and sustainable diets more available and accessible. This means, for example, the prominent placement of healthy products in retail outlets.

5. What role does scientific advice, including from the GCSA, play in policymaking?

Scientific advice supports evidence-based policymaking by analysing scientific findings on a given topic, based on high-quality science.

Scientific advisors are intermediaries between science and policy. They need to demonstrate their trustworthiness by following a transparent and an impartial process to analyse evidence. The GCSA works closely with the Science Advice for Policy by European Academies – or SAPEA – consortium. SAPEA assembles multi-disciplinary groups of the best European experts on the topics for which advice is requested by the College of Commissioners.

On matters such as food systems, for which strong vested interests exert influence on policymaking, it is essential to provide independent, science-based recommendations.

6. How can consumers help drive change? 

Consumers can contribute through well-informed purchasing decisions that are consistent with their values.

But models of behavioural change recognise that motivation alone isn’t sufficient to modify diets. Consumers also need to have the capability and opportunity to adopt new behaviours.

Consumer behaviours are influenced both by personal factors – such as taste preferences, attitudes and knowledge – and by external factors, mainly price, information and social and cultural norms.

All factors must be addressed. Hence the need for a raft of diverse measures targeting the whole food environment that complement each other.

7. What should be the balance between international and local food trade?

Evidence shows that locally produced food isn’t always more sustainable than food imported from abroad. For example, some vegetables grown in Europe in greenhouses may use more energy input than vegetables grown in Africa.

Yet, to promote sustainable consumption, the EU could restrict imports of food commodities from places where food production causes major environmental damage – for example, foods from biodiversity-rich and carbon-dense ecosystems, water-demanding crops produced in water-scarce areas and seafood sourced from unsustainably managed stocks.

Some of these restrictions are already covered by new EU legislation on deforestation-free products.

8. How can the EU help ensure that small farmers get treated fairly?

Small farms may struggle to adapt to new regulations as they may lack the capacity to invest in new practices and production systems.

Yet they play a key role in some European regions for providing food, maintaining cultural landscapes and keeping rural areas socially attractive.

Small farmers aren’t always as well represented in multi-stakeholder policy dialogues as their large counterparts. Therefore, new policy measures should anticipate possible adverse effects on small farms and be monitored and periodically reviewed to ensure they don’t have unintended consequences.

9. What are the main social and political challenges to change?

As in every transformative process, there is resistance from vested interests who benefit from the status quo. It is critical to create an environment that allows all stakeholders to work towards the goal of healthy and sustainable food.

This approach may also help to overcome opposition from those who profit from the current system, including some large private-sector organisations with powerful voices. For example, food-industry representatives have much more resources to defend their case than, say, future generations, thereby creating an imbalance in the debate.

Civil-society organisations have an important role in representing the voiceless.

10. What role does animal well-being have in all this?

Animal welfare is a key ethical dimension of sustainability. It is also central to a “One Health” perspective that integrates the health of people, animals and the environment.

People shift to plant-based diets for health, environmental and/or animal-welfare motives. All three motivations are equally important and they point towards the same direction: decreasing the consumption of animal-sourced products and decreasing intensive animal farming.

This creates an opportunity for companies with a focus on quality products and high animal- welfare standards. For policy, a meat tax framed as an “animal-welfare levy” might be more socially acceptable than an environmental tax.

This article was originally published in Horizon, the EU Research and Innovation Magazine. 

French ski resort closes permanently because there’s not enough snow, CNN informs. Winter is coming. And for yet another ski resort in France, that means facing up to the reality that there isn’t enough snow to carry on.

La Sambuy, a town which runs a family skiing destination near Mont Blanc in the French Alps, has decided to dismantle its ski lifts because global warming has shrunk its ski season to just a few weeks, meaning it’s no longer profitable to keep them open.

“Before, we used to have snow practically from the first of December up until the 30th of March,” La Sambuy’s mayor, Jacques Dalex, told CNN.

Last winter, however, there was only “four weeks of snow, and even then, not much snow,” he added. That meant “very quickly, stones and rocks appeared on the piste.”

Able to open for fewer than five weeks during January and February, Dalex said the resort was looking at an annual operating loss of roughly 500,000 euros ($530,000). Keeping the lifts going alone costs 80,000 euros per year.

La Sambuy isn’t a huge resort, with just three lifts and a handful of pistes reaching up to a top height of 1,850 meters (about 6,070 feet).

But with a range of slopes running from expert “black” to beginner “green” and relatively cheap ski passes, it was popular with families seeking more of a low-key Alps experience than offered by bigger, higher-altitude destinations.

UK snow report website On The Snow calls it “an idyllic place to visit, with exceptional panoramic views and everything you need in a friendly resort.”

La Sambuy is not the only French ski resort facing a meltdown. Last year, Saint-Firmin, another small Alpine ski destination, opted to remove its ski lift after seeing its winter season dwindle from months to weeks, a situation also blamed on climate change.

Mountain Wilderness, a French environmental group, says it has dismantled 22 ski lifts in France since 2001, and estimates that there are still 106 abandoned ski lifts across 59 sites in the country.

According to a report published in August by the scientific journal Nature Climate Change, 53% of 2,234 ski resorts surveyed in Europe are likely to experience “a very high snow supply risk” at 2 degrees Celsius (3.6 Fahrenheit) of global warming above pre-industrial levels, without use of artificial snow.

A report published in January in the Proceedings of the National Academy of Sciences journal found a “substantial possibility” of global temperature rises crossing this 2-degree Celsius threshold by mid-century.

La Sambuy’s Dalex said that “all winter sports resorts in France are impacted by global warming,” particularly those at a medium mountain altitude between 1,000 and 1,500 meters.