Science news in brief: From a duck-like swimming dinosaur to the flavour molecules in salami

A round-up of science stories from around the world

No one knows exactly how many Sumatran tigers remain, estimates range from about 400 to 500, down from 1,000 in 1978 (Getty)

Sometimes seeing more endangered tigers isn’t a good sign

A new study containing good news about the population of this endangered cat also carried a disclaimer that there was probably no cause for optimism.

The study, published in Nature Communications, relied on images from more than 300 trap cameras as well as data from decades of similar studies. The authors reported that tiger density in Sumatra’s three largest protected forests increased 5 per cent per year from 1996 to 2014, suggesting that Indonesia’s preservation efforts are slowly working.

However, the increase was probably caused by an influx of tigers fleeing unprotected forests on the large western island in the Indonesian archipelago, where their numbers are dropping rapidly, the researchers said.

That means small gains in the protected areas are probably dwarfed by the species’ overall decline.

“Densities have increased, but that has not reduced the threat of extinction because the habitat is being cut down and fragmented,” said Matthew Luskin, a research fellow with the Smithsonian Institution in Singapore and an author of the study. “You’re basically packing more tigers into smaller areas.”

Though no one knows exactly how many Sumatran tigers remain, estimates range from about 400 to 500, down from 1,000 in 1978. The animals are only on Sumatra, where their rain forest habitat is quickly being replaced by rubber and palm oil plantations.

– Douglas Quenqua

You should think of hummingbirds as bees with feathers

In Mediaeval Europe, some called bees the smallest birds. In Chinese and Japanese, the words for hummingbird translate into “bee bird.” Today, we call the smallest hummingbird – weighing less than a penny and only a bit larger than the biggest bee – the bee hummingbird is the smallest hummingbird.

And now a group of researchers say we should embrace our history of lumping the two together. The way scientists study bees could help them study hummingbird behaviour, too, they argue in a review published in Biology Letters.

Scientists first compared the two back in the 1970s when studying how animals forage. The idea is that animals use a form of internal mathematics to make choices to minimise the work it takes to earn maximum rewards. Researchers at the time focused on movement rules, like the order in which they visited flowers, and where flowers were located relative to others. It was “almost like an algorithm” for efficient foraging, said David Pritchard, a biologist at the University of St. Andrews in Scotland who led the review. Hummingbirds and bees had similar solutions.

But the study of optimal foraging, as it was called, overlooked what animals learned about their environments. Bees decipher which flowers are more rewarding than others. They learn about colour and how to manipulate a flower among other information. Decades before the concept of optimal foraging, Frank Bene, a US ornithologist, discovered that hummingbirds learned about colour too, contrary to the belief that they were innately attracted to red.

– Joanna Klein

Tracking dolphins with algorithms you might find on Facebook

Researchers have tried deploying underwater sensors to eavesdrop on the clicks dolphins use for echolocation, which can give clues about the aquatic mammals’ numbers, distributions and behaviours.

In a study published in PLOS Computational Biology, scientists from the Scripps institution of oceanography in California introduced an algorithm that was able to analyse 52 million dolphin clicks and identify seven distinct groups of sound. These click types, the authors speculate, may correspond to different kinds of dolphins.

After the Deepwater Horizon oil spill happened in 2010, Kait Frasier wanted to monitor how dolphins were doing, and so created acoustic sensors around the Gulf of Mexico. She wanted to leverage the machine learning techniques used by Google and Facebook to improve the method of going through the clicks which previously took her three weeks to analyse a year’s worth of recordings from a single site. But the algorithm took about four days to sort through two years of data from five sites.

Through an “unsupervised” process – meaning the authors did not train the algorithm to recognise any particular categories beforehand – the program came up with seven discrete click clusters.

One of these was consistent with the unusual click profile of a species called Risso’s dolphin, which suggested their method might work, Frasier said.

–Steph Yin

What happens when you microwave a boiled egg

A recent investigation into exactly how microwaved eggs explode, so to speak, and the volume of the resulting boom, was set off by a lawsuit.

A diner at a restaurant claimed that in addition to burns, his hearing had been damaged when he bit into a reheated, hard-boiled egg. Anthony Nash and Lauren von Blohn, acoustics experts at Charles M Salter Associates, were engaged to look into whether the sound could be damaging.

Nearly 100 eggs were sacrificed for the cause, and while most did nothing but lie there, about a third exploded gratifyingly.

It soon became clear that the sound of the eggs going off, while loud, wasn’t particularly dangerous at a distance of a foot, ranging from 86 to 133 decibels.

When they took the temperatures of the water bath and the egg yolk just after it exploded, there was a very large difference, averaging 22 degrees Fahrenheit (-5 degrees C). The yolk was hotter than 212 degrees (100 degrees C) – in other words, hot enough to boil water. This suggested a potential explanation for this tendency to explode.

– Veronique Greenwood

This duck-like dinosaur could swim. That isn’t the strangest thing about it

Palaeontologists studying an unusual fossil have identified a new dinosaur, related to the velociraptor, that had a neck like a swan, a snout like a goose and forelimbs like flippers. The creature’s hodgepodge of features – so strange that extra work was needed to verify the fossil’s authenticity – suggest that it might have lived on both land and in water.

If so, that would make the species, known as halszkaraptor escuilliei, only the second swimming dinosaur ever found, after the ferocious spinosaurus (though even that is debated).

The clues that suggest it was semiaquatic include its long neck and hooked, crocodile-like teeth, which it may have used to plunge face first at fish from the water surface. The dinosaur also had a snout filled with sensory nerves that are typically seen in crocodiles and used to detect movement and temperature changes in water. Its forelimbs were shaped less like wings and more like flippers, similar to those used by marine reptiles like the plesiosaur to swim.

“It was designed for swimming,” said Pascal Godefroit, a palaeontologist at the Royal Belgian Institute of Natural Sciences in Brussels and an author on the paper, “but which kind of swimming we don’t know.”

The dinosaur’s legs and clawed feet were better suited for running on land. But if the dinosaur used its feet to propel itself in the water, it would not have been as effective a swimmer as a swan or duck, Godefroit said. It also was probably not a diver like some water fowl.

– Nicholas St Fleur

Actually, you do want to know how this sausage gets made

When you slice into a salami, you are enjoying the fruits of some very small organisms’ labour.

Like other dried sausages, salami is a fermented food. Its production involves a period where manufacturers allow microbes to work on the ground meat filling to create a bouquet of pungent, savoury molecules. Traditionally, the bugs find their way to the sausage from the surrounding environment. But these days, industrial manufacturers add a starter culture of bacteria to the meat instead.

It’s safer this way, and leads to more consistent results. These industrial starters may not always yield the most inspired flavour, though.

A recent study from researchers at the University of Turin, published in the journal Applied Environmental Microbiology, found that salami made with wild bugs scored higher with tasters than salami made with a starter culture. The amount of acid produced by the industrial bacteria as it works over the meat might explain the difference.

– Veronique Greenwood

© New York Times