Where is the best place to sleep? Black bear: A nest of gold or silver is not as good as a bird's nest | Nature Trumpet

Welcome to the 40th issue of the Nature Trumpet column. In the past two weeks, we have collected the following natural news and research worth reading:

1) The black bear was sleepy and took a nap in the bird's nest

2) Ancient giant whales were heavier than blue whales, but their heads were ridiculously small

3) To attract mates, male moths use aphrodisiacs

4) Yangtze River dolphins have smart coats that keep them warm in winter and cool in summer

5) Killer whales eat whale sharks, cut out their livers and run away

6) The dog’s facial expressions are related to its appearance

Black bear takes a nap in a bird's nest

It sounds outrageous - researchers recently found a black bear sleeping in a bird's nest !

The incident took place in an eagle's nest in Alaska. When the bear was found, it was sleeping soundly in the nest. Two months ago, a helicopter also happened to take pictures of this eagle's nest. At that time, there was a female bald eagle incubating eggs in it, but now the original owner has disappeared.

Black bear: Well, let me sleep at your house for a while | USFWS

In Alaska, black bears are notorious for attacking eagle nests, killing cubs, but this sleeping black bear may be innocent - scientists suspect that the nest was abandoned by the bald eagle a long time ago, and the black bear may have just found this good place to take a nap while climbing a tree, so he went in.

A female bald eagle incubates eggs in a nest in May. | Cayley Elsik / JBER Environmental Conservation

Among North American birds, the bald eagle builds the largest nest , which can reach a diameter of 2.4 meters and weigh more than 2 tons. It is no wonder that such a spacious place attracts black bears. Moreover, black bears are generally used to building beds on steep slopes to sleep, so as not to be disturbed by other animals. This eagle nest is near the black bear's bed, and there are always rotten fish in the nest that have not been eaten . The black bear may have found this place by following the smell of fish.

Ancient giant whale, heavier than the blue whale

The blue whale used to be considered the heaviest known creature on Earth, but now, its status is in jeopardy - scientists have discovered an ancient giant whale in Peru that is heavier than the blue whale.

Reconstruction of an ancient giant whale | Alberto Gennari / Nature

According to estimates, this newly described ancient giant whale lived 39 million years ago and weighed between 85 tons and 340 tons , which was about twice as heavy as the blue whale. However, compared with the blue whale, the ancient giant whale was short and fat - they were only 20 meters long, while the blue whale could reach 30 meters.

Ancient whales looked strange, with ridiculously small heads but huge bodies , perhaps a bit like modern manatees. Their bones were surprisingly heavy, with the entire skeleton estimated to weigh 5 to 7 tons, the heaviest skeleton among known mammals . Scientists believe that it is precisely because of the heavy bones that they can hold down the buoyant blubber and air in their lungs, otherwise they would only float on the water.

Paleontologist Mario Urbina with ancient whale vertebrae | Martin Mejia

The discovery of the ancient giant whale was purely accidental. Thirty years ago, a paleontologist was looking for fossils in the desert of Peru and came across bones exposed on the ground. He tried to dig down, but found that the bones were very large and the excavation work took a lot of time. In the end, 13 vertebrae, 4 ribs and 1 hip bone were excavated on the spot, and each vertebra weighed more than 100 kilograms .

Workers are moving one of the vertebrae | Giovanni Bianucci

Unfortunately, the head and teeth of the ancient giant whale did not survive, so we have no way of knowing its eating habits . Scientists speculate that they usually stayed on the seabed, did not exercise much, and probably ate krill and small marine life in the water.

Aphrodisiac for moths

In order to attract the opposite sex, male moths do not hesitate to use "aphrodisiacs".

The aphrodisiac is methyl salicylate, a chemical derived from plants that is released when attacked by herbivores , both for its healing properties and to attract the herbivore's enemies (the enemy of my enemy is my friend).

Moth | Kai Squires

The amazing thing is that methyl salicylate acts as an aphrodisiac for female moths. Researchers have found that even ultra-low concentrations of methyl salicylate can cause strong reactions in female moths . Male moths cleverly take advantage of this - when they chew plants as larvae, they absorb methyl salicylate released by plants; when they are courting, they mix methyl salicylate into their pheromones , making female moths unable to stop.

Congratulations to the male and female guests for successfully holding hands | Reference [3]

It turns out that aphrodisiacs do play a decisive role in whether male moths can successfully mate . Once the researchers reduced the amount of methyl salicylate in their pheromones, their mating success rate immediately dropped; after adding a small amount of methyl salicylate, the mating success rate returned to normal levels.

From the female's perspective, methyl salicylate is an aphrodisiac because it reflects the male's masculinity . The smell of methyl salicylate on a male means that it can defeat the plant's defense system, which means that the male is healthy and strong and can be a suitable mating partner.

Smart jacket for Yangtze finless porpoises

The water temperature is too hot in the summer and too cold in the winter, what should marine life do? The Yangtze River dolphin has a solution - the thickness of its fat layer can change with the seasons , like a smart coat.

Recently, Tang Bin and other researchers from the Institute of Hydrobiology of the Chinese Academy of Sciences found that the thickness of the fat of Yangtze River dolphins changes with the water temperature . In winter, the fat of the dolphins turns into a "down jacket" to help them resist the cold river water; in summer, the fat turns into a thin "T-shirt" to keep the dolphins cool.

The “smart coat” of the Yangtze River dolphin | Tang Bin

The fat version of the "smart coat" of the finless porpoise has different working modes in different parts of the body. The fat on the back is the thickest and most sensitive to water temperature. When the water temperature rises, its thickness decreases linearly. On the sides and abdomen , the thickness of the fat will only decrease significantly when the water temperature rises above 18°C.

Researchers discovered the secret of finless porpoise fat through B-ultrasound imaging. The white arrows above are the thick subcutaneous fat layer. Reference [4]

But how does the thickness of fat change according to the water temperature?

In fact, what really changes with the seasons is the appetite of the finless porpoise . Like many people, when the temperature is high in the summer, the finless porpoise will consume less energy and the thickness of its fat will also decrease; when the water temperature is low in autumn and winter, they will enjoy eating and store fat. But if it is a pregnant female finless porpoise , the high water temperature will not significantly reduce their appetite, and their fat will remain thicker, so that they can store energy for raising their cubs.

Remember to have more food when it's cold | Huangdan2060 / Wikimedia Commons

Killer whales eat whale sharks

Previously, there was a pair of killer whales in South Africa that made sharks tremble with fear . They were named "Port" and "Starboard".

They have hunted dozens of sharks and only ate the sharks' oil-rich livers, discarding the rest.

A similar scene was recently captured off the coast of Mexico - a killer whale ripped open the stomach of an adult whale shark and ate its liver .

A killer whale rips open the belly of a whale shark | James Moskito/Ocean Safaris

Witnesses said that after the killer whale spotted the 8-meter-long whale shark, it first swam upside down below it, then quickly tore open its stomach and took out its liver. The whale shark just sank and remained motionless, probably dead; and the killer whale returned to the surface, the whole process only took a few seconds . Not long after, they saw the killer whale successfully attack and kill another whale shark.

This is the first known video of a mammal attacking an adult whale shark. Whale sharks are the largest fish in the world . Adult whale sharks can grow to more than 10 meters. Apart from threats from humans, almost no animal in nature dares to provoke whale sharks - obviously, killer whales have become the exception now.

Dog Expressions

How dogs look can affect how they interact with humans.

In a new study, scientists recruited more than 100 dogs and gave their owners a set of standards to score the complexity of their dogs' faces - dogs with solid facial colors and no lines received 1 point, and if the face had multiple colors and lines, the score would increase accordingly, with a maximum of 9 points. The results showed that the simpler the face of the dog, the more expressions they made when interacting with humans .

This dog has multiple colors and patterns on its face and scored 7 points, making it a dog with a complex face. | Reference [6]

The study also found that, overall, dog owners were able to judge their dogs' expressions , but owners were most accurate in assessing the expressions of dogs whose faces were solid and smooth and who were between the ages of two and seven.

Older dogs seem to be "playing bad" and are less expressive than younger dogs when communicating with humans. Scientists believe that this is not because they have become lazy, but because they have lived with their human companions for a long time, the relationship is very strong, and they know each other well. Therefore, dogs do not need to work hard to make expressions, and their owners can understand what they mean .

Working dogs: Super detectives, serious about solving cases! | US Air Force

The nature of dogs also affects their expressiveness . Domestic dogs only need to communicate with their owners, and sometimes they can get by with a mix of different languages. Working dogs are completely different - as "social animals", they must report any disturbances in a timely manner, so their expressiveness is the ceiling among dogs .

Domestic dogs: Just make do, what else can you do? | Gerardolagunes / Wikimedia Commons

References

[1] https://www.livescience.com/animals/bears/black-bear-caught-napping-in-a-bald-eagles-giant-nest-on-alaska-military-base

[2] https://www.nature.com/articles/s41586-023-06381-1

[3] https://www.sciencedirect.com/science/article/pii/S096098222300917X

[4] https://www.sciencedirect.com/science/article/pii/S2772735123000859

[5] https://www.livescience.com/animals/orcas/watch-orca-tear-open-whale-shark-and-feast-on-its-liver-in-extremely-rare-footage

[6] https://www.mdpi.com/2076-2615/13/14/2385

Author: Cat Tun

Editor: Mai Mai

Title image source: USFWS

This article comes from GuokrNature (ID: GuokrNature)

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