A desert ant species constructs mounds to use as navigational landmarks, which help them find their way home in their otherwise flat Saharan habitat.

Desert ants are famous for their wayfinding skills, and many travel long distances to collect food to bring back to their colony. But these foraging trips are an especially daunting task for ants like Cataglyphis fortis, which live in salt flats in Tunisia and so must find the thumbnail-sized entrances to their underground nests without the aid of landmarks like plants, hills and water features.

at the Max Planck Institute for Chemical Ecology in Germany and colleagues decided to investigate the purpose of mounds built by C. fortis after noticing their varying heights. Mounds near nests at the shrub-covered edges of the salt pan were barely noticeable, while those in the centre could reach taller than 25 centimetres, suggesting that they were important for navigation.

The researchers began by following the insects’ locations with GPS and found that they face high mortality rates. On the longest journeys, which were more than 2 kilometres, around 20 per cent of the ants failed to make it home and died in the baking heat.

The researchers then followed ants at 16 nests. At some of them, they removed nearby mounds and at others, the researchers left the area completely alone. They found that removing the mounds increased the chances of ants failing to find their way home by between 250 and 400 per cent. In nearly all cases, the foragers’ nest mates quickly began rebuilding the missing structures.

When Knaden and his team replaced the mounds with artificial landmarks – black cylinders the size of large fire extinguishers – they found that the ants didn’t rebuild. “It’s an enormous effort to build such a nest hill. There are hundreds of ants building the whole night,” says Knaden. “So they don’t do it if they don’t have to.” With the artificial landmarks, ants took more direct paths home like they did before their mounds were levelled.

“We are used to discovering myriad ways that insect foragers use clever tricks to help with their efficient navigation, but I was a little taken aback when this stretched to nest architecture,” says at the University of Sussex in the UK.

The remaining mystery is how the colony keeps track of when it needs new landmarks. C. fortis colonies have divisions of labour, so older foraging ants could be communicating to the young ants responsible for construction that they need landmarks. Or it could be an initiative younger ants take when they see their older colony mates struggling to return.

They’re back. Scimitar-horned oryx have been reintroduced to the wild after a two-decade absence and are flourishing in their old stomping grounds.

The desert antelopes were once widespread across northern Africa, but were hunted to extinction in their natural habitat in the 1990s.

Since then, the species has been kept alive in captivity in the United Arab Emirates, the US, Europe and Australia. Several hundred have also been reintroduced to fenced areas in northern Africa.

To test whether scimitar-horned oryx could survive in the wild once again, 23 individuals were released into a remote part of Chad last August. Based on early signs of success, another 23 will be released this week.

The animals have been fitted with GPS collars to monitor their movements. “So far, the animals look exceptionally healthy,” says from the Smithsonian’s National Zoo and Conservation Biology Institute in Washington DC, who is involved in the project. “They seem to be adapting to the environment really well.”

First baby in the wild

Some of the released oryx were pregnant and, in September, the first calf was born in the wild since the species went extinct. “He seems very lively and healthy, so that’s encouraging,” says Stabach.

The next test will be whether females that became pregnant after release will produce healthy offspring, he says. “We’re expecting some births in the next month or two.”

The oryx were reintroduced in the Ouadi Rimé-Ouadi Achim reserve, an expansive of unfenced wilderness in central Chad, which used to be the species’ stronghold.

A group of about 40 to 50 of the antelopes were taken from this area in the 1960s. Most oryx alive today are thought to be descended from these animals.

Fewer threats

Although the newly released oryx all come from this small population, their genetic diversity has risen because separate captive populations were kept around the world. This has allowed them to genetically drift apart from one another.

Reintroducing oryx to the wild is less challenging than doing so with many other animals, says at the University of Sydney, Australia. One reason is that they eat grass, so they don’t need to be taught how to hunt for food. Another reason is that their natural predators – lions and cheetahs – have gone extinct in the area.

Hunting by humans is also not a problem so far, says Stabach. “There’s a lot of excitement in the local community about this animal being returned. They want to protect it.”

“Conservation scientists are all giving big thumbs up and cheering over this,” says Hogg. “Animals are often bred in captivity in zoos with the view of releasing them back into the wild, but then there are always lots of challenges. It’s pretty amazing to know that you can put them back.”

Read more: Reviving Europe’s long-lost beasts through mass rewilding; Rewilding: Bring in the big beasts to fix ecosystems

Here’s a bright idea for flat-packing. A German start-up has figured out how to cram an entire solar power plant into a shipping container. It has sent its first kits to off-grid villages in Africa, where they provide a new source of clean, affordable electricity after just 2 hours of assembly.

More than 620 million people in sub-Saharan Africa have no access to electricity, a situation that can keep people in poverty. And population growth means this . Those with access tend to rely on inefficient diesel generators, chugging along with crippling financial and environmental costs.

Despite that, diesel is standard for off-grid energy. “If there’s no diesel, there’s no electricity,” says Rolf Kersten of the start-up, in Hainburg, Germany, which shipped its first solar generator to Mali in December last year.

Kersten’s team is using crowdfunding to build its containerised power plants. Solar panels and batteries are packed up and folded into a standard shipping container. On arrival, the equipment unfurls around the container with minimal assembly, and starts generating electricity. “For remote places away from a grid, these kinds of solution are very promising,” says at the University of York, UK.

Air pollution is a pervasive, silent killer in Africa, says Evans. Diesel generators pump out smoke particles, fostering a host of respiratory and cardiac diseases. Generator emissions also contribute to acid rain, which impacts crop yields and biodiversity, as well as carbon dioxide that contributes to global warming. Solar power has none of these problems.

Lighting up Mourdiah

GreenTec sent its first container to Mourdiah, a village in south-west Mali a few hours’ drive from the capital Bamako, last September. Before then, only a few villagers had access to patchy electricity. Now, 120 houses are connected to a local grid.

To power Mourdiah’s nightlife, the container stores electricity in batteries, as well as producing it from solar panels. Enough energy is stored to light up the village for several hours each evening. “Most life starts at night there”, says Kersten. Education, for instance, takes place in the cooler evenings.

Studies of rural electrification have not always painted a rosy picture. In 1994, the World Bank found that the high costs of providing electricity to rural areas often meant the people it was intended to help could not afford it. Energy from GreenTec’s containers is cheaper than that produced by the diesel generators it replaced, though.

“This technology is generally sound and can be great for supporting communities off the grid,” says Mark Borchers, director of . “The social aspects are often the trickiest. Who pays? How much? Who’s in charge? Who gets the power?”

The next version of GreenTec’s generator is bigger, with more panels and double the battery capacity. It should store enough juice to last a village like Mourdiah through the night, powering everything from lighting to built-in water pumps. One container set to arrive in the village of Nafadji in Mali this December has a built-in water-purification system that uses solar power.

The containers will be useful anywhere with a lot of sunlight that isn’t connected to a national grid, and everywhere from hotels to hospitals, says Kersten. Across the African continent today, that’s hundreds of millions of people who could really use some power.