Grizzly bears, which may grow to about 2.5m long and weigh over 400kg, occupy a conflicted corner of the American psyche-we revere(敬畏) them even as they give us frightening dreams. Ask the tourists from around the world that flood into Yellowstone National Park what they most hope to see, and the iranswer is often the same: a grizzly bear.
"Grizzly bears are re-occupying large areas of their former range," says bear biologist Chris Servheen. As grizzly bears expand their range into places where they haven't been seen in a century or more, they're increasingly being sighted by humans.
The western half of the U.S. was full of grizzlies when Europeans came, with a rough number of 50,000 or more living alongside Native Americans. By the early 1970s, after centuries of cruel and continuous hunting by settlers, 600 to 800 grizzlies remained on a mere 2 percent of their former range in the Northern Rockies. In 1975, grizzlies were listed under the Endangered Species Act.
Today, there are about 2,000 or more grizzly bears in the U.S. Their recovery has been so successful that the U.S. Fish and Wildlife Service has twice attempted to de-list grizzlies, which would loosen legal protections and allow them to be hunted. Both efforts were overturned due to lawsuits from conservation groups. For now, grizzlies remain listed.
Obviously, if precautions(预防) aren't taken, grizzlies can become troublesome, sometimes killing farm animals or walking through yards in search of food. If people remove food and attractants from their yards and campsites, grizzlies will typically pass by without trouble. Putting electric fencing around chicken houses and other farm animal quarters is also highly effective at getting grizzlies away. "Our hope is to have a clean, attractant-free place where bears can pass through without learning bad habits," says James Jonkel, longtime biologist who manages bears in and around Missoula.
Scientists are excited by the rediscovery of the giant lacewing. It is an insect which looks like across between a fly and a moth. It has spotted wings with a span of roughly 50 millimeters, holding the wings over its body like a tent.
Giant lacewings have been around since the Jurassic era, a period of time about 150 to 200 million years ago. In the 1950s, scientists thought giant lacewings had disappeared from eastern North America. However, scientists recently confirmed that one had been spotted.
Michael Skvarla works for Penn State University, who is the director of its insect identification lab. Skvarla found the giant lacewing in 2012. He remembers it clearly. "I was walking into Walmart to get milk and I saw this huge insect on the side of the building," Skvarla said. "I thought it looked interesting, so I put it in my hand and did the rest of my shopping with it between my fingers. I got home, mounted it and promptly forgot about it for almost a decade."
Then, in late 2020, Skvarla was teaching biodiversity in a Zoom class during the pandemic lockdown. During the class, Skvarla showed his students microscopic images of the insect he had seen at Walmart. Together, they stared at the images. They studied the insect closely. Then, they realized that the insect had been wrongly labeled. Many scientists are stirred by this discovery. Now they have started wondering if there may be entire populations hiding out, which requires for further investigation.
And the causes of the supposed disappearance of the insect have long been a mystery. With a deeper research, there are some possible explanations. One is light pollution, which is the brightening of the night sky from man-made light sources such as street lights. Light pollution can disrupt the natural cycles of living things. Another cause could be the introduction of non-native insects such as ground beetles. They can cause harm to the environment. Ground beetles prey on giant lacewings. People's stopping forest fires may also play a part in the disappearance of the lacewing. This is because giant lacewings need ecosystems that rely on natural fires.
Aussie Ark is an animal preservation project based near the Barrington Tops of New South Wales, Australia. Originally known as Devil Ark, its original goal was to only breed（培育）and preserve Tasmanian devils（袋獾）.
About the size of a big domestic cat, the Tasmanian devil is the world's largest living marsupial carnivore（有袋食肉动物）. Its bigger cousin， the Tasmanian tiger，died out in 1936. Devil numbers were stable until 1996, when a strange disease suddenly began destroying devil populations across Tasmania. Devil facial tumour disease (DFTD), within a few months, is an infectious cancer spread by bites during fights over food and mates. There's still no cure despite a quarter-century of dedicated research, and devils have suffered an 80-90 per cent decline. A second type of DFTD, just as deadly, was identified in 2014.
After the devil was declared endangered in 2008, increased effort went into establishing isolated DFTD-free insurance populations. Tasmania's offshore Maria Island supports a small introduced group of healthy devils, and the Forestier-Tasman Peninsula has the only disease-free population in its native range, but Aussie Ark has more devils than both the above two and is the biggest and wildest mainland breeding facility. As an innovative and wildly successful conservation project, Aussie Ark has spent the last decade creating a healthy mainland population of the endangered Tasmanian devils, mainly by letting them act naturally in a large-scale bush shelter. A big part of its success is the suitability of its landscape. The Ark's cool-climate, high-altitude (1, 300m)snow-gum forest has proved very devil-friendly. Launched in 201l with 44 DFTD-free devils, Aussie Ark has bred more than 350 devil babies now, a record outside Tasmania, and holds over half the devils in mainland Australia.
Two separate research groups in the U. K. and Denmark have come up with the same idea for a study that could help save endangered species, and have gotten the same results. It involves sucking environmental DNA from the air that animals leave behind.
"We use a really small pump that pulls the air through, and we hope the DNA gets caught on the filter（过滤器）," said Elizabeth Clare， the lead researcher. "It's a bit like making coffee. You make coffee by sucking water through a filter and leaving the coffee grounds behind. That's basically what we're doing; we're just sucking the air through and hoping that the DNA gets lost behind. "
Clare says the concept has been used for years in different ways. Scientists sample pathogens（病原体）from the air, which has been used to help track COVID-19. Environmental DNA can also be collect d from water to help ease invasive species.
A big goal for both research teams with the new study is to be able to locate endangered species and help save them. It is important to note that this type of DNA sampling can only be picked up if a species is in the area, so if there were two of the same animal, scientists would not be able to tell which one the DNA came from.
Both research groups also reported certain DNA samples not showing up when they knew an animal had been in the area. They also can't tell yet how long an animal's DNA will stick around after it's been in one area. Clare says she'd like to plan more researches to get these answers.
But one thing is for sure after conducting the study. Clare says she has a whole new perspective on taking a deep breath. "Asyou know, I'm walking through a jungle or the park or taking my dog for a walk or my kids out to play, and I take a deep breath; I think I just inhaled information about all the things that have been here before, and as a scientist, that's exciting to think that the information that I'm trying to gather is literally hanging in front of me, "she said.
Sulphur-crested cockatoos (葵花凤头鹦鹉) are common in western Australia, where they normally live in wooded areas. But as forests have been cut down, cockatoos have gotten used to living near people. Scientists report that people in Sydney, Australia are in a battle with these birds.
Last year, scientists at the Max Planck Institute reported that the cockatoos had learned how to open the covers of trash bins. That's not an easy job. The cockatoos must lift the heavy cover with their beaks (喙) and then walk along, pushing the cover up until it falls over.
When scientists first began studying the cockatoos in 2018, only three areas near Sydney had cover-opening cockatoos. A year and a half later, cockatoos in 44 different areas knew the trick. This time the scientists weren't just studying cockatoos. They were also studying humans.
The scientists spent weeks studying more than 3,200 trash bins in four different areas of Sydney. They wanted to see how many bins were protected and what methods were used.
In one area, over half the bins were protected. The most common way of protecting the bins was to put a brick or some other heavy objects on the cover. Some people put things like rubber snakes on the top of their bins. The scientists discovered that the humans were teaching each other tricks, too. In most neighborhoods, many people used the same cockatoo-stopping methods as their neighbors.
The researchers say it's like a race between humans and cockatoos to learn new ways of doing things. Now many cockatoos have learned how to push heavy items off the bins. As a result, humans have figured out ways to attach the items to the top of their bins. The scientists describe the situation as a "human-wildlife conflict". They expect these conflicts will become more common as humans take over more areas that used to be wild.
Many animals and plants are endangered in the world today. These endangered species are threatened with becoming extinct, meaning they will no longer exist on Earth. Examples include the Cuban Macaw and the Sri Lankan Legume Tree. Illegal hunting, and collecting of the Macaw bird for pets, led to its extinction. While the main reason the native Sri Lankan Legume Tree went extinct was due to habitat loss from development in the 20thcentury. The main cause for animals and plants disappearing is often a damage to the food chain due to hunting, habitat loss or even the introduction of invasive species.
Every living thing from one-celled animals to a blue whale needs to eat. Nature is connected and controlled by many fragile food chains. A food chain describes who eats whom in a habitat. When one of the links in a food chain is no longer present -for example, a species goes extinct-the food chain breaks and sometimes this can cause other animals to disappear and the whole system can become imbalanced or even collapsed.
Humans can have disastrous effects on food chains. When people first explored the world, they took animal and plant species from their home countries to the places they explored and settled in. They did not realise the consequences of introducing invasive species. By doing so, they were damaging the natural food chains of the areas they explored.
Nowadays there are strict rules controlling the movement of animals and plants between countries. But some parts of the world are still experiencing problems with invasive species introduced hundreds of years ago.
With rising awareness of how we affect the natural environment, hopefully we can lean to protect these food chains and help them to thrive. Otherwise the continued loss of species will eventually mean our own extinction.
