Some pretend to be shit, some pretend to be dead, you frogs are really cunning! | Nature Trumpet

Welcome to the 45th issue of the Nature Trumpet column. In the past half month, we have collected the following natural news and research worth noting:

1) Young frogs hide their poop to avoid being eaten by birds

2) Female frogs play dead to scare away males

3) Wildlife-only highway exit

4) As the climate warms, salmon need cooling stations

5) The world's largest pumpkin, over 1 ton

6) Wildlife Photography Awards Announced

Young frogs pretending to be poop

This is the black-palmed tree frog. When they are young, they can actually pretend to be poop !

Juvenile black-palmed tree frog (Rhacophorus nigropalmatus) | References [1]

When young, black-palmed tree frogs are brown with white spots, a color scientists consider unusual because the brown color would make them more conspicuous against a green background, making them more likely to be eaten— unless this is some fancy cosplay, like pretending to be bird poop .

They made tree frog models of different colors out of wax and placed them in a rainforest house with many bird predators. Reddish-brown wax frogs were more likely to be attacked by predators than green wax frogs; however, once the reddish-brown wax frogs had white spots on their bodies, the chance of being attacked was immediately reduced by half. Scientists believe that the brown with white spots is exactly what bird droppings look like, and the white parts are white crystals formed by uric acid, so at first glance, birds will only think that the reddish-brown wax frog is just the same kind of urination and defecation .

Reddish brown, reddish brown with white spots and green wax models of tree frogs | References [1]

However, filling their poop is only a temporary solution. When black-palmed tree frogs grow up, they will transform from ugly ducklings into white swans, turning into bright emerald green, and the white spots will disappear. At this time, if they encounter the threat of predators, they will spread the skin membrane between their toes and limbs and glide between trees. They can glide more than 10 meters in one breath to avoid predators.

Black-palmed tree frog (adult) | Rushenb / Wikimedia Commons

Female frog plays dead

The young frogs above can pretend to be feces, and some adult female frogs have another skill - playing dead .

This time it is not to avoid predators, but to avoid hungry males . Wood frogs reproduce explosively during mating season. Since the number of males far exceeds that of females, a large group of males often swarm around a female frog, forming a "mating ball". The female is caught in the middle and sometimes even dies.

Wood frog (Rana temporaria) during breeding season | Thomas Brown / Wikimedia Commons

If females do not want to mate with certain males, or are not ready to mate, they will stretch out their limbs and lie motionless for about 2 minutes. Researchers believe that this may be because females want to avoid mating and pretend to be dead , or it may be because of physiological stiffness due to excessive stress.

Wood frogs mating | Mikhail Nevsky / Wikimedia Commons

Playing dead isn't the only skill of female forest frogs. They can also refuse to mate by imitating the sounds of males . Researchers have found that female frogs held by males sometimes make grunting or squeaking sounds. The grunting sound is the male's call for "release", and the meaning of the squeaking sound is still uncertain. These sounds will make the male think that he has caught the wrong person, so the female frog can take the opportunity to escape. If pretending to be a male's call doesn't work, they will use the killer move of pretending to be dead.

High-speed animal exit

The highway has its own dedicated exit for wildlife, and they love using it.

In Texas, the United States, in order to prevent wild animals from accidentally entering the highway and being hit by cars, people initially installed wire fences on the roadside. However, the result was counterproductive - those wild animals that jumped over the wire fences or dug holes underground were trapped on the road by the nets .

After installing the exit, the coyote successfully returned from the road to the habitat. RH indicates the direction is road - habitat. Reference [3]

So, in 2018, people added 10 funnel-shaped wildlife exits to the highway . This was originally designed specifically for Texas ocelots. Due to hunting and habitat loss, there are only 50 to 80 ocelots left in the United States, all in Texas. The designers hope that the ocelots can return to the wild from this exit.

Um, my bobcat friend, you went the wrong way. How did you get from your habitat to the road? | Reference [3]

Unexpectedly, when researchers recently checked the cameras near the animal exits, they found that these exits had become popular passages for various wild animals .

There are 10 mammals leaving the highway through this exit, such as hares, opossums, etc., including bobcats and coyotes, which are very similar in size and habits to ocelots. Just like human rush hour, the wildlife exit has its own peak time - around 10 pm and before dawn, the most animals pass through here .

You guys are in a hurry to leave | References [3]

Unfortunately, the cameras at the exit have not captured any signs of ocelots. But the researchers are not discouraged, after all, the number of ocelots is too small. Since bobcats and coyotes have learned the correct way to use the exit, it means that they should also be applicable to ocelots .

Although no ocelots were spotted near the exit, other cameras along the highway did capture ocelots. | Kline Lab, University of Texas Rio Grande Valley

Salmon Cooling Station

People have built a summer station for salmon to help them survive the warming climate.

Wild Atlantic salmon are born in fresh water, but spend most of their lives in the cold ocean until they migrate to fresh water to spawn. Migration usually occurs in the summer, when the river temperature is the highest, and they usually find some cool tributaries or natural groundwater to rest temporarily along the way. However, there are fewer and fewer natural summer waters, and many salmon die on the way to migration .

Thermal imaging shows a significant drop in river surface temperature after the cold water was pumped in | Kathryn Smith

In order to allow the salmon to successfully migrate and spawn, scientists have designed two artificial thermal shelters for them. One is to pump 9°C cold water into the 30°C river water through the government's backup well; the other is to dig an underground ditch to allow the water to release heat into the surrounding soil before returning to the river, thereby lowering the temperature of the river.

The scientists tested both methods and were pleasantly surprised to find that they were both successful. The river water successfully cooled by several degrees - and the salmon must have felt it, because they could sense even a 0.1 °C change in water temperature. The cameras showed that the artificial thermal shelters had indeed become a summer resort for the salmon, who gathered here for a short rest and to recover their energy before continuing on their journey.

Salmon gather in artificial hot shelters | Kathryn Smith

Next, scientists plan to build more artificial shelters to add a little coolness to the salmon's migration route.

The biggest pumpkin

Recently, someone grew a giant pumpkin weighing 1.25 tons, breaking the world record for the largest pumpkin .

The world's largest pumpkin, so big that it blocks out the sun | Reference [5]

The pumpkin, which weighs as much as a hippopotamus, was named "Michael Jordan" by farmer Travis Gienger, who won the World Pumpkin Championships and received $30,000 in prize money.

The Ginger Family and the Big Pumpkin "Michael Jordan" | Miramar Events

This big pumpkin competition has a long history and can be called the Super Bowl of pumpkins. It is held every year on Halloween. This year is the 50th. Pumpkin farmer Kinger grows big pumpkins in his backyard . Compared with other big pumpkins grown in greenhouses, his pumpkins are particularly eye-catching. In the past four pumpkin Super Bowls, Kinger has won three championships. Last year's champion pumpkin also came from his backyard and weighed 1.16 tons. This year's champion pumpkin set a new record.

Next, the pumpkin "Michael Jordan" will be on tour, and people from all over the world will come to see it. After the exhibition, a famous pumpkin carver will carve it in November, and King may also auction the seeds of the big pumpkin at that time.

Wildlife Photography Awards

Recently, the results of this year's Wildlife Photographer of the Year competition were announced. Among about 50,000 photos, 19 photos were finally awarded. The following are some of the winning works:

Golden horseshoe crab

Photographer: Laurent Ballesta

The overall winner was French photographer and marine biologist Laurent Ballesta, who captured this photo of the golden Chinese horseshoe crab and three toothless trevally swimming alongside it on the seafloor in the Philippines.

The Chinese horseshoe crab is a living fossil that has existed in the ocean for 400 million years. Its blue blood is used in vaccine research and development, so it is fished in large quantities and is now endangered. Three young toothless trevally followed the horseshoe crab, probably waiting to eat the food it dug up as it slowly moved forward.

Life on the Edge

Photographer: Amit Eshel

Two Nubian ibexes clashed on a cliff. After a 15-minute standoff, one of them gave up and they went their separate ways.

Last gasp

Photographer: Lennart Verheuvel

The photographer captured the last moments of a stranded killer whale. Although it was rescued, it died soon after, and a subsequent autopsy found that it was very ill.

The unprotected

Photographer: Karine Aigner

In Texas, bobcats, which are not protected by hunting regulations, are hunted ruthlessly.

Wave-making whale

Photographer: Bertie Gregory

The killer whales rushed towards the ice, creating waves that flushed the seals into the water for food.

Silence for the Snake

Photographer: Hadrien Lalagüe

The gray-winged trumpetbird is famous for its loud call, but when a giant python more than 3 meters long passes by them, they can only remain silent collectively, otherwise they will become a delicious meal for the python.

The last breath of autumn

Photographer: Agorastos Papatsanis

The fungus releases spores from under the cap, creating a beautiful and dreamy moment in the photographer's lens.

References

[1] https://link.springer.com/article/10.1007/s00265-023-03376-w

[2] https://royalsocietypublishing.org/doi/10.1098/rsos.230742

[3] https://www.frontiersin.org/articles/10.3389/fevo.2023.1235223/full

[4] https://gsa.confex.com/gsa/2023AM/meetingapp.cgi/Paper/392393

[5] https://phys.org/news/2023-10-gourd-hippo-sized-pumpkin-world-biggest.html

[6] https://www.theguardian.com/environment/gallery/2023/oct/11/2023-wildlife-photographer-of-the-year-winners-in-pictures

Author: Cat Tun

Editor: Mai Mai

Title image source: Rushenb

This article comes from GuokrNature (ID: GuokrNature)