The number of birds in North America has declined by almost 3 billion since 1970, according to a study published in Science. The researchers estimated changes in the populations of 529 species using long-term bird-monitoring databases. Those data showed that the number of individual birds across all of those species had decreased by 29 percent, from around 10 billion in 1970 to just over 7 billion in 2017.

“The data they used provide probably the best long-term, large information on species abundances for any group of animals or plants anywhere in the world,” Natalie Wright, a bird biologist tells The Atlantic. “There’s always uncertainty, but if they are wrong, they are likely underestimating the size of population declines.”

The team also examined 10 years’ worth of data from a network of 143 weather radars, which pick up bird migrations, and found a reduction in migratory biomass of about 14 percent since 2007. “Two completely different and independent monitoring techniques thus signal major population loss across the continent,” the authors wrote in their paper.

The results are particularly concerning because many of the species showing declines are not considered rare or in danger, but are almost everywhere and potentially act as important contributors to food webs and ecosystem function. More than 90 percent of the loss in abundance in the survey data was due to declines in 12 families, including sparrows and blackbirds. Some other species, including many ducks, instead showed increases in abundance—possibly as a result of focused conservation efforts in recent years.

The findings should be a wake-up call. Many of the birds studied spend time in multiple countries within and beyond North America. What our birds need now is a historic, global effort that unites people and organizations with one common goal: bringing our birds back.

Record sea ice loss caused a mass die-off of emperor penguin chicks in part of Antarctica last year, strengthening predictions that the world’s largest penguin will soon be in danger of extinction.

Unlike other penguins, emperors breed (繁殖) on sea ice rather than land.Male emperor penguins hatch the eggs during the Antarctic winter. The furry grey chicks need stable sea ice until December to grow their black waterproof feathers and gain enough muscle to swim. If they go into the water before they develop feathers, chicks can drown or freeze to death.

In February, the area of sea ice around Antarctica reached the lowest extent ever observed. After much of the ice began breaking up late last year, four out of five habitats in the hard-bit central and eastern Bellingshausen Sea suffered a total breeding failure, with no chicks surviving to the feather growing period. In mid-November, the sea ice there broke up, forcing the penguins to abandon the habitat and most if not all of their chicks.

A research team from Oxford Brookes University monitored populations by spotting penguin faeces (排泄物) in satellite photos. Emperor penguins tend to stay close, walking in a tight group to stay warm in temperatures as low as -60°C.The buildup of the habitat’s faeces stains the ice so brown that it can be seen from space. Once a habitat has been identified, researchers can count the individual penguins in very high-resolution satellite images.

The observations add weight to modelling predictions that 90 percent of emperor penguin habitats could be extinct or past the point of no return by 2100 if current rates of warming continue. While habitats can lose chicks in heavy storms or when severe winds break up the sea ice, this is the first-time widespread breeding failure has been linked to disappearing ice.

“Failure is the norm, but complete failure across a whole region, that’s not normal,” says Tim at Oxford Brookes University. “Will this impact the population? It really depends on how often it happens.”

The hippo is a very important animal to the health of African rivers and lakes. However, researchers warm that the population of hippos is becoming less.

The hippo is a large animal. Hippos spend nearly 16 hours a day in the water. They come ashore to feed at night, and they eat more than 200 kilograms of grass every time they eat.

Professor Douglas McCauley and his team have studied the waste of hippos. He says, “We have looked carefully at hippos and found that the most useful thing is their waste. They eat lots of grass on land and then take that all back to the lakes and rivers where they rest. They basically get rid of that in the form of waste. And it turns out to be a huge amount of matter full of energy and Nutrients.”

Every year, hippos provide over 60,000 kilograms of waste for African lakes and rivers. Some fish need the waste in their diets. And some of the nutrients in the waste are the building materials of some small plants in the water.

Although researchers learn more about the importance of hippos, there are fewer of them. The number of hippos has dropped a lot in Africa. Douglas says humans are mainly responsible for it due to illegal hunting And animals, including hippos, often lose to humans in competition for water. Douglas explains, “Both of them need water.” He says when we’re harming wildlife, we should realize that our future is closely inked with wildlife's.