Adelie Penguins Poop So Much, Their Feces Can Be Seen From Space
pically, humans have sent satellites into space to hunt for the most otherworldly and mysterious objects: black holes, quasars and exoplanets. But at least one NASA-funded team is using our eyes in the sky to study one of the most worldly and least mysterious objects: they’re using satellites in space to monitor massive penguin poop stains.
The krill-heavy diet of Adélie penguins, which live on the coast of Antarctica and the remote islands nearby, turns their guano a striking pink color. When contrasted with surrounding snow, the guano shows up pretty well in LandSat images. Brian Resnick at Vox reports that researchers at the American Geophysical Union conference recently explained how they are using those images to find remote penguin colonies and even reconstruct the diet and history of the colonies over time.
The satellite images don’t show individual penguins, since they are much too small to be seen. But the immense accumulation of bright pink poo is relatively easy to spot, which allows researchers to calculate the colony's size.
“Male and female penguins take turns incubating the nest. The guano left behind builds up in the same areas occupied by the nests themselves,” co-investigator Heather Lynch, an ecologist at Stony Brook University says in a NASA press release. “We can use the area of the colony, as defined by the guano stain, to work back to the number of pairs that must have been inside the colony.”
Yasemin Saplakoglu at LiveScience reports that the team spent 10 months poring over clear satellite image of Antarctic islands to create a global survey of the species. The team thought they’d done a thorough job, but once they started using an algorithm to help them find poop-peach colored pixels, they discovered they’d missed quite a few of the waddling birds. In particular, they’d overlooked a massive 1.5 million strong colony on Heroina Island in the remote Danger Islands. When a team traveled to the suspected roost, they found the computer was indeed right and the island was teeming with the birds.
“We thought that we knew where all the [Adélie] penguin colonies were,” Lynch said during a new conference. “We, I think, had missed it in part because we hadn't expected to find them there.”
The team is reviewing satellite images dating back to 1982 to learn about the population rise and fall of individual Adélie colonies. They’ll also examine the color of the massive skid marks to learn about the penguins’ diets over time. When the penguins are munching on fish, their guano tends to come out white, but the more krill they eat the pinker the waste becomes.
To test their idea, the team collected guano from the colonies, which it turns out is not as fun as it might sound.
“Penguin guano almost has the consistency of a wet tuna salad,” co-investigator Casey Youngflesh, a postdoc at the University of Connecticut, tells Resnick. “The guano has a pungent fishy scent and is definitely not pleasant. It’s something you just have to learn to cope with.”
After powering through the stench and analyzing the guano, the team found that their diet estimates from the satellite images correspond pretty closely with what the penguins are actually eating. However, when they compared the diet data with fluctuations in colony size, they were surprised to find there was no strong connection.
“It is interesting that no obvious trend in diet was seen over time, despite changes in the physical environment,” Youngflesh says in the press release. “This was a big surprise, since the abundance and distribution of Adélie penguins has changed dramatically over the last 40 years and scientists had hypothesized that a shift in diet may have played a role.”
In fact, some colonies have seen dramatic population crashes, while others have remained stable or grown larger, and researchers would like to understand these changes better. Getting a handle on the size of the colonies and their natural fluctuations over time is the first step to understand what is happening. That will help researchers manage and protect the penguins as more man-made threats, including climate change and krill fishing, which harvests the tiny crustaceans for the health supplement industry, put more pressure on their nesting grounds.
While that number is dramatic, it isn’t unprecedented, according to Brian Resnick at Vox. Resnick reports that historically, caribou go through natural boom and bust cycles, which means herds will grow to number in the hundreds of thousands then steeply decline to the tens of thousands, only to bounce back once more. But in the latest report, part of NOAA’s particularly grim 2018 Arctic Report Card, researchers are beginning to wonder if the populations have fallen too far to recover.
“The fact that these herds are declining shouldn’t be a shock — they do it all the time,” ecologist Don Russell, who authored the caribou section of the report, tells Resnick. “But they’re at such low levels, you start to be concerned. ... If we return in 10 years and [their numbers] have gone down further, that would be unprecedented… [The question now is] are their numbers so low they can’t recover?”
According to a NOAA press release, only one of the 23 major caribou herds in the Arctic, the Porcupine herd in Alaska, is near its historic population high of around 200,000 animals. The remaining three herds in Alaska have dropped by 57 percent since reaching peak numbers between 2003 and 2010. In Canada, nine herds of caribou have declined so sharply they have been listed as threatened and two herds of migratory caribou in the eastern part of the country have been given endangered status. In total, five of the 22 herds of caribou in the Alaska-Canada region have dropped nearly 90 percent, and scientists are concerned they will never rebuild. In Russia, 18 out of 19 herds are showing major signs of decline.
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