Friday, September 5, 2025

Polaris of Enlightenment

Study: Butterflies can cross the Atlantic Ocean

Biodiversity

Published 30 June 2024
– By Editorial Staff
The painted lady butterfly (Vanessa cardui)
3 minute read

The painted lady butterfly (vanessa cardui) can fly over 4200 kilometers and has a route that spans the Atlantic Ocean, research shows. This is the longest distance ever recorded for an insect, and the first time scientists have observed a butterfly flying across the ocean.

It was in October 2013 that Gerard Talavera, a CSIC researcher at the Botanical Institute of Barcelona, identified several painted lady butterflies on the Atlantic beaches of French Guiana. These observations were quite unusual, as this species is not found in South America.

They decided to try to trace the flight paths of the butterflies, which they did by analyzing wind trajectories, and also to study the genetic diversity of the butterflies, which they did by collecting painted lady butterflies from populations on all continents. They found that the specimens observed in South America were related to populations in Europe and Africa. In addition, the researchers analyzed the pollen DNA that the butterflies carried on their bodies and identified two plant species found only in tropical Africa, proving that the butterflies visited flowers in that region.

Finally, the researchers analyzed the stable isotopes of hydrogen and strontium from the butterflies’ wings. The wings retain isotopic signatures unique to the place where they grew up as caterpillars, making it possible to trace their origins. It was found that the butterflies likely originated in Western European countries such as France, Ireland, the United Kingdom or Portugal.

– The painted lady butterflies reached South America from West Africa, flying at least 4200 km over the Atlantic. But their journey could have been even longer, starting in Europe and passing through three continents, implying a migration of 7000 km or more. This is an extraordinary feat for such a small insect, said Clément Bataille, a professor at the University of Ottawa in Canada, in a press release.

With the help of the wind

Scientists have calculated that a flight can take between five and eight days for the butterfly, and without stopping. With the help of the wind, it makes the flight possible.

– The butterflies could only have completed this flight using a strategy alternating between minimal effort to avoid falling into the sea, facilitated by ascending winds, and active flight, which requires more energy consumption. We estimate that without wind, the butterflies could have flown a maximum of 780 km before exhausting all their fat and thus their energy, says Eric Toro-Delgado, one of the authors of the paper.

The researchers highlight the Saharan air layer as a potential ‘highway’ for air dispersion. These wind currents transport large amounts of dust from the Sahara to the Americas and participate in important biogeochemical cycles. They emphasize that the biological components, including living organisms, transported by these winds need further study.

However, this discovery suggests that there may be natural air corridors that connect continents and facilitate the spread of species on a much larger scale than scientists previously thought.

– This discovery opens new perspectives on the capabilities of insects to disperse over long distances, even across seas and oceans. It is possible that we are underestimating the frequency and impact of these movements on our ecosystems, said Gerard Talavera, leader of the study.

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Swedish moose population rises after years of decline

Biodiversity

Published 3 September 2025
– By Editorial Staff
This year, 72,328 moose may be hunted in Sweden, which is an increase of just over 9,000 moose compared to last year.
2 minute read

After ten years of decline, Sweden’s moose population is increasing, according to the Swedish University of Agricultural Sciences (SLU). This means that more moose can be shot during this year’s moose hunting season, but despite the increase, the moose may still be red-listed as a threatened species.

In 2012, Sweden introduced new moose management policies aimed at finding compromises between different interests and setting population targets. The moose is often seen as a national symbol of Sweden and is one of the most important animals for hunting. At the same time, they cause wildlife accidents, often with fatal outcomes, and damage forests – according to SLU.

Every five years, the Species Information Centre at SLU compiles a red list of species considered threatened. SLU has also been calculating changes in the moose population since 2021. As recently as last year, researchers believed that the species had declined so significantly that it would risk being red-listed in the next compilation, scheduled for this year. This was due to the moose population decreasing in large parts of the country over the past ten years.

More hunters abstain

Now the population has increased, according to the latest report from SLU. Before last autumn’s hunt, Sweden had approximately 300,000 moose, representing an increase of about ten percent compared to the previous year.

One reason, according to the report, is that more and more hunters have refrained from shooting some of the moose they encounter. In particular, they have avoided shooting cows that are expected to give birth to next year’s calves.

– It’s naturally expected that the moose population increases if we shoot fewer moose. But it’s important to find out by how much, and to try to understand why hunters no longer seem to comply with shooting targets, says Fredrik Widemo, university lecturer at SLU and coordinator of the moose research project, in a press release.

May still be red-listed

This means that for this year’s hunt, which began this week, more moose can be shot than last year. This year, 72,328 moose may be shot in the country, an increase of just over 9,000 moose compared to last year.

Despite the increase, the moose may still be red-listed, but the preliminary proposal is to place it in the red list’s lowest category as “near threatened”.

New study of national park: Wolves helped nature recover

Biodiversity

Published 17 August 2025
– By Editorial Staff
A wolf in Yellowstone National Park during 2016.
2 minute read

The return of wolves to Yellowstone National Park has contributed to an ecological recovery after decades of damage to plant and animal life. Now a new study shows that the park’s aspen populations are finally beginning to reestablish themselves – apparently thanks to the predator’s impact on the ecosystem.

During the 1930s, wolves were completely eradicated from Yellowstone National Park in the Rocky Mountains of the United States. This had major consequences for the ecosystem – as the deer population increased dramatically and began grazing intensively in the park. This led to a sharp decline in trees like aspens. Aspen is considered a keystone species in the park, and its decline affected other species that depend on the deciduous trees, including beavers, insects and birds.

In the 1990s, wolves were reintroduced to the park, which immediately changed the deer’s behavior – not only by taking some as prey, but primarily by causing the deer to stop grazing for long periods in the same places. The result was that vegetation recovered, which has had a major effect on biodiversity.

Remarkable change

Now researchers have documented the first new generation of aspens in the park. In the study, which was published in Forest Ecology and Management, researchers argue that the wolf’s return has contributed to the species’ recovery.

The reintroduction of large carnivores has initiated a recovery process that had been shut down for decades, says the study’s lead author Luke Painter, who teaches ecology and conservation at OSU College of Agricultural Sciences, in a press release. About a third of the 87 aspen stands we examined had large numbers of tall saplings throughout, a remarkable change from the 1990s when surveys found none at all.

Another third of the examined stands had areas with tall saplings that were growing up to become new trees in the canopy layer, while the rest were still being held back by grazing. Researchers believe this may be due to bison increasing in certain parts of the park. The fact that stands with many tall saplings have low levels of grazing, while others continue to be held back, suggests that aspen recovery depends on an ecological chain reaction where predators affect plant life by reducing the number of grazing animals – rather than on factors like climate or soil fertility.

This is a remarkable case of ecological restoration, says Painter. Wolf reintroduction is yielding long-term ecological changes contributing to increased biodiversity and habitat diversity.

Radioactive method ready for use against poaching

Biodiversity

Published 11 August 2025
– By Editorial Staff
Rhinos are being injected with radioactive material.
2 minute read

After an extended testing period, the Rhisotope project in South Africa is now in full operation. The technology, which makes rhino horns both traceable and unattractive to poachers, can now be used on a large scale.

It was in June last year that researchers injected radioactive material into the horns of 20 rhinos in South Africa. The project, called the Rhisotope Project and led by the University of the Witwatersrand (Wits University) in South Africa, began six years ago with the idea of stopping poaching of the endangered rhinos. The concept was that the radioactive material should be detectable at border controls, but also becomes toxic to consume. Furthermore, the radioactive material should be harmless to the rhinos.

Now the project has been thoroughly tested and reached full operational status, writes Wits University in a press release.

We have demonstrated, beyond scientific doubt, that the process is completely safe for the animal and effective in making the horn detectable through international customs nuclear security systems, says James Larkin, professor at Wits University and scientific director of the Rhisotope Project.

Sold as “medicine”

Rhino poaching is a recurring problem, particularly in South Africa. Last year, 420 rhinos were killed illegally in the country, where the horns often end up on the black market. They are often sold as medicine and can be worth more than gold. The treatment is carried out by sedating the rhino and then drilling a small hole in its horn. Two small isotopes with radioactive material are then inserted.

This means in practice that private and public rhino owners, non-governmental organizations and conservation authorities can contact the Rhisotope Project to treat their rhinos with the radioactive material.

Our goal is to deploy the Rhisotope technology at scale to help protect one of Africa’s most iconic and threatened species. By doing so, we safeguard not just rhinos but a vital part of our natural heritage, says Jessica Babich, CEO of the Rhisotope Project.

Swedish crayfish threatened with extinction

Biodiversity

Published 10 August 2025
– By Editorial Staff
From 30,000 population to under 600 – the noble crayfish is critically endangered.
2 minute read

Crayfish plague continues to devastate Sweden’s native noble crayfish. In just a few decades, populations have plummeted from around 30,000 to fewer than 600 – and the trend continues downward.

The biggest culprit is illegal releases of non-native signal crayfish, which are themselves heavily fished and can also be affected by the disease.

The signal crayfish, which spreads the disease, has increased dramatically and today exists in between 10,000 and 15,000 populations. In Värmland, a province in western Sweden, illegal releases have been documented in as many as 239 bodies of water between 2000 and 2024.

— Noble crayfish populations in Värmland and Dalsland were 430 in the early 2000s; today only 60 remain, says Lennart Edsman, crayfish expert and researcher at the Freshwater Laboratory at the Swedish University of Agricultural Sciences (SLU), to Swedish news agency TT.

When August and crayfish season arrives, the question arises of which species the environmentally conscious consumer should choose for their crayfish party.

— You should eat noble crayfish if you can afford it. That gives them value that makes them worth protecting. And you should eat signal crayfish too, but absolutely not spread them, Edsman believes.

Imports worth hundreds of millions

Swedes eat far more crayfish than the country can produce. Between 70 and 80 percent of the crayfish on tables are imported. In 2023, imports amounted to a value of €40 million, while Swedish crayfish were sold for €27 million.

Previously, the largest portion of imports came from China, but today Spain, Turkey and also Egypt dominate the Swedish market.

Most Swedish-caught crayfish are signal crayfish, with a large share coming from lakes Vättern and Hjälmaren in central Sweden. Recently, however, many consumers have complained that the crayfish have become smaller.

— This is partly because fishing has been too intensive. There is great demand for crayfish in this country. Sweden is quite extreme when it comes to crayfish consumption, Edsman explains.

The signal crayfish originates from western North America, as does crayfish plague – a parasitic algae fungus. Although the species is more resistant than the noble crayfish, it is not immune to the disease.

How the signal crayfish took over

The signal crayfish originally comes from western North America and was introduced to Sweden in the 1960s as a way to replace the noble crayfish, which had been severely affected by crayfish plague at the time. The idea was to preserve crayfish fishing and its economic benefits, since the signal crayfish is more resistant to the disease than the noble crayfish.

The problem is that the signal crayfish carries the very crayfish plague – a parasitic water mold – that is deadly to the noble crayfish. Although the invasive species itself can be affected, it is significantly more resilient, which means it functions as a disease carrier and accelerates the decline of the noble crayfish.

Since its introduction, the signal crayfish has spread rapidly and is now found in between 10,000 and 15,000 populations across Sweden. Many of these have resulted from illegal releases. The consequence is that the noble crayfish has declined from around 30,000 populations to fewer than 600 throughout the country.

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