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Category Birds

How do greater sage grouse inflates?

The greater sage grouse lives in North America. It is the largest species of grouse in that continent. It is a massive white-breasted bird with brown-black features on its head and back. The male has two yellow sacs on each side of the throat. In breeding season, the male inflates the sacs to amplify the pooping sounds it makes to lure the females. All the males gather in a spot called a lek and strut their stuff. They can be heard up to five kilometres away!

Other birds, such as the magnificent frigatebird and the great bustard also inflate their throat sacs called gular pouches. The frigatebird has a striking red one and it spends an hour inflating it.

 

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How Harbour seals navigate at night?

Indian and Polynesian sailors have historically been guided by lodestars to find their way at sea. But research shows that harbour seals have been doing it much before humans attempted it. Harbour seals are marine mammals. They live along the Atlantic and Pacific coastlines of the Northern Hemisphere, and hunt for food at night. Obviously, in the dark, they cannot follow the landmarks that are visible on land.

In 2006, German and Danish scientists placed two harbours seals – named Nick and Malte – in a specially constructed floating planetarium. The team trained the two to swim in the direction of specific lodestars. They discovered that the animals could identify a single star out of a projection of the Northern Hemisphere night sky. This showed that the seals followed specific lodestars as navigational aids when they swam far from the shore. Remember, this was an experiment. So do the seals in the wild navigate by following individual stars? Researchers believe they do. Star-based navigation enables the seals to efficiently search an area for food.

 

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How birds navigate at night?

Scientists say migrating birds rely on the magnetic compass after sunset. They also use the individual stars for navigation at night. All animals with “camera eyes”, the kind of eyes humans have, can make out individual stars. Insects with compound eyes cannot do this so they see the starry sky and the Milky Way as patterns of light. But scientists do not have an answer for one question: how do birds flying at night change the point of reference when they cross the equator? How do they follow the stars that change their orientation across the equator?

One example of birds that understand stellar navigation is the indigo bunting of North America. These birds fly south for winter, and they do it at night. There is less competition for food at night and there are fewer disturbances after dark. In one experiment, researchers captured these migrating birds and placed them under a starlit dome. And this is what they found.

Indigo buntings watch the rotation of close star patterns around a centre point, such as the North Star. From this they determine the directions. Before migrating, songbirds orient themselves by hopping in the direction they want to travel. In the experiment, the starlit dome rotated around the North Star, which is what happens in the night sky. The smart birds observed it and began to fly south. Then the researchers removed the constellations within 35 degrees of the North Star. The birds became disoriented and couldn’t fly anywhere.

So, individual stars are not that important for the birds. What they need to see is the rotation of the close star patterns around a centre point. This helps them to determine where north is. They use this information to fly south.

 

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How Dung beetles navigate at night?

Whenever we talk of the navigational skills of explorers, we wonder: How did these seafarers find their way about the sea with no navigational aids like sat-nav? The answer is always the same. Sailors of olden days followed the stars. They understood star formation and aligned their route to how the stars appeared in the night sky. But man is not only the creature that “followed the stars.” Sea creatures and birds are known to have looked up to the heavens for guidance. Recent studies in this field show that dung beetles too use the stars for navigation! And they have a brain the size of a grain of wheat!

Dung beetles are African insects. During the day, the beetles walk in a straight line rolling the dung. The beetles survive because of the dung. The dun provides them with food and drink, and during the hot African noon, the beetles simply climb on the dung to keep themselves cool. So the beetle fights for the smallest bit of dung, and carries it away even during the night.

At night, moonlight is their guide. On the days the moon is not visible, dung beetles follow the Milky Way. Human, birds and sea creatures follow just the lodestar. Just one star is enough for them. But the eyes of the dung beetle are not that sharp. The Milky Way has a straight band that is easy for the beetles to follow. For the Milky Way to be seen, the sky has to be clear. So, should we not keep the sky clear, without pollution, so the poor beetles trying to cart their food do not lose their way?

 

Picture Credit : Google

How do birds navigate during migration?

Many species of birds migrate. Migration is driven mostly by weather and the availability of food. They often travel the same course year after year with little deviation. The secrets of their amazing navigational skills aren’t fully understood. The birds are believed to combine several different types of senses when they navigate. They seem to have an internal GPS (global positioning system) that allows them to follow the same pattern every year.

Birds may depend on the sun, the stars, and the earth’s magnetic field to find direction. Scientists believe that birds likely follow the landscape to find their migratory destination. Visual makers, distinct sounds and smells. And learned social cues may play a significant part in this process.

Individual organs may also contribute a bird’s navigational ability. A bird’s eyes, inner ear (which has tiny amounts of iron in the ear neurons) and the trigeminal nerve, which connects the beak and brain of the bird, help them determine their exact position. The trigeminal nerve is thought to help birds evaluate the strength of earth’s magnetic field, which is stronger at the poles and weaker at the Equator.

 

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What are the some interesting facts about the diverse species?

  1. Parrots are intelligent birds. How do we know this? Scientists tell us that they are capable of complex thinking – the genes that play a role in their brain development are similar to those that evolved to give humans large brains. One example of this is the way parrots make noises that resemble sounds we make syringes conversations. We click our tongue in a particular way to convey, “Not going to happen.” Parrots click their tongue to make very similar sounds. It is quite astonishing to know that humans and parrots have similar traits.
  2. In one experiment, the genome of the blue-fronted Amazon parrot was compared with that of 30 other birds. The results showed that regions of brain development genome in parrots are the same as those found in humans. Humans ended up with bigger brains and more brain cells and so capabilities, including language skills than primates. Parrots have bigger brains than other birds and more communication skills.
  3. Parrots live far longer than expected based on their body size and metabolism. Some live up to 80 years. Parrots genes associated with lifespan help repair DNA damage, slow down cell death due to stress, and limit cell overgrowth and cancers. Amazing!
  4. According to New Scientist, wild keas (a New Zealand mountain parrot with a long, narrow bill and mainly olive-green plumage) sometimes burst into playful behaviour when they hear recorded laughter. They are the first bird known to respond to laughter-like sounds. What did they do? The keas soared one after the other in aerobatic loops, exchanged foot-kicking high fives in mid-air and tossed objects to each other. They behaved like they were copying one another. When the recording stopped, they simply went back to whatever they were doing.
  5. The playful behaviour of the keas is accompanied by a special warbling call they make. This is significant because it looks like the laughter they are exposed to is contagious, just like it happens in human conversations. All the birds in a flock – male, female, young ones – join the fun. One report said, “On hearing the calls, many birds started to spontaneously play with non-playing birds, or with an object close by, or by performing aerial acrobatics.”
  6. The African grey parrot Alex was said to have the intelligence of a five-year-old human. Researchers at the University of York and the University of St. Andrews observed captive greater vasa parrots (Coracopsis vasa) using date seeds and pebbles to break cockle shells. Male vasas ate the powder and then offered a regurgitated calcium-rich snack to females before mating.
  7. Parrot toes are zygodactyl. Have you noticed the toe-arrangement on the parrot’s foot? Parrot toes are aligned for maximum grip: two in front and two behind, like two pairs of thumbs opposite to each other. Beaks that can crack the world’s toughest nuts and feet that have a solid grip together make parrots dexterous climbers and healthy nut-eaters.
  8. Parrots generally are omnivores – they eat fruits, seeds, nuts, insects and even meat. Rainbow-coloured Lories and lorikeets of the South Pacific use their brush-tipped tongue to sip nectar and are ready to eat meat when available. Keas were found to attack and kill sheep in 1868.
  9. Of the roughly 350 known species of parrots, most live in the tropical and subtropical regions of Australia, Asia, Central and South America and Africa. Keas live in the alpine regions of New Zealand and nest in ground burrows. The endangered maroon-fronted parrot (Rhynchopsitta terrisi) lives 6000 feet above ground in the Sierra Madre Oriental Mountains of Mexico.
  10. Though parrots do have some taste glands at the backs of their throats, most of their 300 or so taste buds are located on the roofs of their mouths. Compared with the 10,000 taste buds in a human mouth, the birds’ palate may not seem like much, but parrots do show definite preferences for certain foods.
  11. Parrots come in different shapes and sizes. The pygmy parrot (Micropsitta pusio) weighs a mere ounce and is about the size of our finger. The world’s longest parrot is the brilliant hyacinth macaw (Anodorhynchus hyacinthinus). It is nearly 3.5 feet from tip to tail. A fully-grown, flightless, nocturnal kakapo (Strigops habroptilus) of New Zealand can weigh as much as nine pounds.
  12. A parrot’s brilliant plumage contains Psittacofulvins, a bacteria-resistant pigment that only parrots are known to produce.

It gives the birds’ feathers red, yellow and green colouration. They also protect the glorious     plumage from degradation.

 

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Why are the numbers of the Indian vulture declining?

          Not many of us find vultures attractive or friendly. Rather, they look a little threatening. But these birds, we should know, play a very important role in the food chain- they feed on animal carcasses, and prevent the spread of deadly bacteria and fungus into the ground and water.

          Sadly, the population of the vulture species is falling at an alarming rate. One of the birds that is facing the risk of extinction is the Indian vulture. It is a wild bird, native to India, Pakistan, and Nepal.

           Like others, Indian vultures too, feed on dead bodies. They can be spotted in cities, towns, and villages near cultivated and open areas, and in woodlands too.

          As per the IUCN Red List, Indian vultures are critically endangered, with a population of around 30,000. A serious decline in their numbers happened in the 1990s, when they lost around 95 per cent of the individuals.

          This unnatural death toll was caused by the presence of diclofenac, a drug used to treat livestock.

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Why is the Asian koel unique?

 

          The Asian koel is better known by its voice than by its looks. The Asian koel stays almost completely atop trees and never comes down to ground. It is as big as a crow, but is leaner, with a longer tail. The famous koel song actually belongs entirely to the males. Females do not sing. Young male birds make harsh, crow-like sounds. But even the adults do not sing during winter.

          The Asian koel is also a brood parasite. It leaves its eggs, which are slightly smaller, but similar to crow’s eggs, to be raised in crow’s nests. These birds feed on berries, banyan and peepal figs and hairy caterpillars.

          Apart from the Indian sub-continent, these birds are also found in China and Southeast Asia. Earlier these birds were popularly raised in cages as pets. 

What are the features of the Indian cuckoo?

            The Indian cuckoo is a medium-sized bird found in forests and open woodlands. Its lower parts are grey in colour, while the upper parts show broad black bars throughout. The tail is also barred, but the tip is white and is preceded by a broader black band. The young birds have a dark face, but the top of their head and chin are contrastingly white in colour.

            The major diet of these birds includes hairy caterpillars and other insects. They are usually found on top of the upper leaf cover of trees, where they search for insects to prey upon. They may catch flying insects in the air, during which they may fly to lower heights too.

            One notable habit of these birds is to leave their eggs for some other bird to rise. They are therefore, called brood parasites. They’ll go to the nest of some other bird to lay their single egg. But before that, they will eat one egg from the host’s nest. The poor host bird will look after the cuckoo egg as its own.

            In India, drongos and crows are the common victims of the cuckoos’ brood parasitism. The Indian cuckoo is very common in India, Bangladesh, Bhutan, Nepal, Russia and Sri Lanka. 

What are the differences between the common myna and the bank myna?

The common myna and the bank myna are different in many ways. The common myna is comparatively larger with a brownish purple plumage. It has a black head. But the bank myna is smaller and bluish-grey in colour. It has some bare skin behind its eyes, which is brick red in colour. In the common myna, this skin is yellowish.

          The common myna is a bold and adventurous bird, mostly found in towns, villages and cultivation lands. They are courageous enough to enter even houses. But bank mynas are milder in their manner.

          The common mynas build nests in holes and they roost communally in tall grasses. They eat invertebrates, fruits, nectar from flowers and even garbage. But bank mynas dig holes in earthen banks of rivers and build their nest in them. Common mynas are found in almost all parts of India. Bank mynas tend to be concentrated in the northern and central regions of the country.