Nature Bytes

Nature Bytes

When breasts and beaks reveal gender

The Himalayas, famous for their lofty mountains, are also home to more than 900 species of birds, 30 of which are found nowhere else. Scientists from India, Germany and USA have studied the characteristics of one such Himalayan songbird called the green-backed tit. The study found that male and female green-backed tits have different body and beak characters.

The green-backed tit is a small songbird that lives across the Himalayas and Taiwan. As the name suggests, they have green feathers on their wings and a black breast stripe running vertically from the throat to their belly, similar to the European great tits. Differences in breast stripes and beak sizes are known to exist between males and females of the well-studied European great tits.

But how different are they in green-backed tits? Can we identify the sex of these birds by just looking at their breast stripes and beak shapes? The researchers of this study have answered these questions by studying a western Himalayan population of green-backed tits.

The researchers measured breast stripe characteristics like colour and width in the birds. They were classified as male and female based on these characteristics. Genetic tests from these individuals later proved that the predictions were correct 97.9% of the time. The study also found a difference in beak lengths between males and females.

Origins of a manakin's golden crown

Three related species of manakins occupy adjacent parcels of the Amazon rain forest: opal-crowned, snow-capped and golden-crowned. They are all plump like sparrows, small enough to cup in a hand and have radiant yellow-green upper bodies with golden undersides. Biologists are now unlocking the mystery of how these neighbouring birds became distinct species.

Recently, a team of scientists confirmed in Proceedings of the National Academy of Sciences that the golden-crowned manakin is a unique hybrid species that emerged from a cross between the opal-crowned and snow-capped manakins about 1,80,000 years ago. Though one-off mating events between different species occur across the animal kingdom, the establishment of an entirely separate hybrid species is thought to be relatively rare.

For a new species to occur, it has to become reproductively isolated, or form a stable population that no longer freely mixes with its parent species, said Alfredo Barrera-Guzmán, University of Toronto, Canada. Opal-crowned manakins wear an iridescent toupee. Snow-capped manakins are topped with bright glacial patches. And members of the hybrid species, the golden-crowned manakin, display a burst of yellow. Scientists found that the manakin's warm crown comes from pigments called carotenoids, which they get from their diet.

Finding the oldest fossils of butterflies

Any curious kids who have caught a butterfly by hand, only to find their fingers coated in messy powder, have unknowingly brushed off the fluttering insect's scales. These microscopic plates cover almost every part of a butterfly, and are what help paint their wings a variety of colours, from shimmering cobalt blues to patterns of orange and black.

While most people go to a garden if they want to see a butterfly's scales in action, Timo van Eldijk's, a Dutch researcher, search for wing scales required drilling more than 1,000 feet into the ground. Then, he extracted fossilised insect bits from black sludge using a probe tipped with human nose hair.

In a study published recently in the journal Science Advances, Timo and his colleagues uncovered approximately 200-million-year-old wing scales belonging to ancient members of the insect order Lepidoptera, which include butterflies and moths. "These scales are the oldest evidence of moths and butterflies," said Timo. "It extends the range to which we know butterflies existed by about 10 million years." The scales may also provide insight into the early evolution of the insect's tubelike tongue, which they suggest evolved tens of millions of years before nectar-rich flowers existed.

Wolverine X

Finland's forests hide a mysterious creature - a dark shadow that has produced a comic book character. This X-beast is a wolverine, a powerful carnivore with a mythical fame.

Wildlife tracker and photographer, Antti Leinonen, spent 19 years in the wilderness of Finland and built up an unexpected image of one delicate, untamed community. He used every deceit to get a glimpse of the life of these secretive animals. Through his approach, the documentary Wolverine X exposes the wolverine in a way never seen before.

Disliked by the public, wolverine numbers have plummeted to precariously low levels. Spending lots of time hidden in the hide is the only way to observe wild wolverines. Over the years, his total commitment has built up an impressive photographic record. To watch the documentary, visit www.bit.ly/2Bdq8y6.

 

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