Recently, Tuthill’s team have shown that an extremely frightening trick helps snow flies survive sub-zero conditions. When a leg begins to freeze, the insects can rapidly self-amputate (自行截肢) it, preventing ice from moving up into their bodies, the team reports in a paper posted online May 30 at bioRxiv.org.

Tuthill’s team used a thermal camera (热成像仪) to record 77 snow flies as they walked on cold plates. They found the insects kept walking even when their body temperature fell to an average of -7℃. More than half of the snow flies tested dropped at least one leg during the experiments.

This team also noticed a temperature rise in the flies’ legs just before they fell off. That rise is a sign of ice formation. Liquid water releases heat as it turns into ice. Neurons (神经元) in the leg may sense this temperature shift and make amputation happen, preventing the ice from spreading, the team suggests. The flies “have about half a second to get rid of their leg before that wave of ice crashes into their body and then freezes all of their internal organs,” Tuthill says. Snow flies didn’t lose their legs when the researchers pulled them hard — only in response to freezing.

“Other animals have invented different strategies to protect themselves from frost. Some insects produce antifreeze proteins; certain snails and frogs simply withstand ice forming in their bodies. The cool thing about snow flies is that they don’t actually follow either strategy” says Dr. Marshall, who provided feedback on the team’s manuscript, which has not yet been published. “They let ice form in their legs,” she says, and “self-amputate to get rid of it, which is just completely strange to me.”

Snow flies that amputated their freezing legs survived more than a minute longer than flies that didn’t, the team found. That extra time may not seem like much. But in the wild, when night is falling and the temperature is dropping and the insects are “looking eagerly for a place to settle down.” Tuthill says, it could be the difference between life and death.

Honey from the African forest is not only a kind of natural sugar, it is also delicious. Most people, and many animals, like eating it. However, the only way for them to get that honey is to find a wild bees' nest and take the honey from it. Often, these nests are high up in trees, and it is difficult to find them. In parts of Africa, though, people and animals looking for honey have a strange and unexpected helper—a little bird called a honey guide.

The honey guide does not actually like honey, but it does like the wax in the beehives. The little bird cannot reach this wax, which is deep inside the bees' nest. So, when it finds a suitable nest, it looks for someone to help it. The honey guide gives a loud cry that attracts the attention of both passing animals and people. Once it has their attention, it flies through the forest, waiting from time to time for the curious animal or person as it leads them to the nest. When they finally arrive at the nest, the follower reaches in to get at the delicious honey as the bird patiently waits and watches. Some of the honey, and the wax, always falls to the ground, and this is when the honey guide takes its share.

Scientists do not know why the honey guide likes eating the wax, but it is very distance away. They will quickly arrive whenever a beekeeper is taking honey from his beehives, and will even enter churches when beeswax candles are being lit.

Homing pigeons combine precise internal compasses and memorized landmarks to re-trace a path back to their lofts — even four years after the previous time they made the trip, a new study shows.

Testing nonhuman memory retention (保持) is challenging; in research studies, “it’s rare that there is a gap of several years between when an animal stores the information and when it is next required to retrieve it,” says University of Oxford zoologist Dora Biro. For a recent study in the Proceedings of the Royal Society B, Biro and her colleagues compared domestic homing pigeons’ paths three or four years after the birds established routes back to their loft from a farm 8.6 kilometers away. The study built on data from a 2016 experiment in which pigeons learned routes in different social contexts during several flights — on their own or with peers that did or did not know the way.

Using data from GPS devices temporarily attached to the birds’ backs, the researchers compared the flight paths a pack of pigeons took in 2019 or 2020, without the birds visiting the release site in between. Some birds missed a handful of landmarks along the way, but many others took “strikingly similar” routes to those they used in 2016, says Oxford zoologist and study co-author Julien Collet: “It was...as if the last time they flew there was just the day before, not four years ago.”

The team found that the pigeons remembered a route just as well if they first flew it alone or with others and fared much better than those that had not made the journey in 2016.

The result is not surprising, says Verner Bing-man, who studies animal navigation at Bowling Green State University and was not involved with the study. But it provides new confirmation of homing pigeons’ remarkable memory, he says: “It closes the distance a little bit between our self-centered sense of human intellectual abilities and what animals can do.”