The Mimicry artist

In last post, we got introduced to Drongos. In this post I will introduce you to their amazing mimicking ability. These amazing birds mimic other species and gather almost quarter of their daily food by mimicking other species. It was observed that these birds make false alarms so that other animals drop their kill and run which gives a window for these birds to swoop in. One of the study claims to have observed them making almost 51 different calls or various species.

You can watch one of such observations here

Drongos are insectivorous birds which are usually found in open forests or bush. Most of them are black or dark grey  and some with metallic tints. They have long forked tails which is more significant in Asian species. 

Drongo is slang for idiot in Australia probably referring to the behavior of only kind of drongo found there i.e. Spangled drongo.

Some of the Drongos you see in India

Black Drongos:

Black Drongo                  Source: Wikipedia

 Glossy black bird with deeply forked tail. Found in open decidous forest and cultivation. Known for their mobbing and driving away predators which makes other species to nest near their nests.

Greater Racket tailed Drongo:

Greater Racket tailed Drongo    Source: Wikipedia

Characteristic long tail, Glossy black drongo with tufted forehead and two long wire like spatula tipped 'streamers' in the tail. Found in deciduous and evergreen forest, bamboo jungle in India, Srilanka

Other kinds of drongos found in India are Ashy drongo, White Bellied drongo, Bronzed drongo, Crow billed drongo, Spangled drongo. They vary mainly in size and found across in various regions.

In the next post we will talk about Weaver birds and their nesting behavior.

Weaver bird along with its nest         Source: Wikipedia

The Science behind Peacocks tail!

Peacocks are male peafowls which are known for their elaborate and distinctive tails. On the other side are female peafowls called peahens which do not have tails. Many would have caught the glimpse of a peacock dance in rain but why do only males have to carry this weight unlike their female partners? This is not a sexist debate but a scientific debate which kept behavior ecologists working for many years with many theories attempting to explain the difference. The difference between male and female plumage is a common occurrence among birds and may not be significant in many cases except for color. But in case of peafowls, this difference is very significant as it is known to affect its survivability in case of an attack by predator. 

Male and Female Peafowl                            Source: Wikipedia

 Over years many theories have emerged to explain this difference, but I am going to talk of one particular theory which I 'think' made a significant impact. i.e. Sexual selection theory. Remember this is just a glimpse of a bigger theory with many nuances which I chose to ignore in interest of time and space. :p

In case of birds, the final choice of choosing partner is  predominantly vested with females. Females build the nest and also take care of the young in most species. Role of males in building nest or taking care of young is minimal in many species. So considering the size of investment they have to make, female birds exercise their right of choosing partner very carefully. Obviously they do not date and chose partners (at least it is not observed so far). So their choice is observed to be mainly based on visual cues. This can be anything from plumage to beak size which females believe to be indicator of 'good' genes. These cues may change over time within same species. This choice of cues for selection is a major field in itself.

Coming to peafowls, it is hypothesized that at some point of time, peahens and peacocks had similar size of plumage like other bird species. The females started 'selecting' (Read more about such selection here) males with bigger plumage compared to others. Over generations this led to bigger plumage and the males today are an outcome of the exhaustion of this process. The size of plumage is related to genes but are these genes indicator for their fitness is yet to be proved. But this selection led peacocks to have bigger plumage compared to their partners. Today this plumage is a baggage and is shown to affect its  survivability in case of a predator attack. May be the plumage is no more an indicator for females due to exhaustion. Many other theories have evolved over years like 'theory relating immunity to its plumage size', handicap theory, etc. Interested people can read more about peacock tail here.

On campus bird is 

Black Drongo                                   Source: Wikipedia

Black Drongo

Black Drongo are black birds which are found across South and South east Asia. They belong to a subfamily of birds with characteristic fork shaped tail (one way to recognize them). Drongos are shown to have certain mimicking abilities which we will talk about in next post.

Hope you are finding these posts interesting. We would love to hear your feedback.

Bird Songs

Almost all bird songs are unique to their species. They are conserved over generations with very little or no variation at all. Cross species song learning is shown to be infective. So both genetics and environment are key for the hereditary transfer of the songs.  The brown thrusher can sing up to 2,000 distinct songs.

A still from Happy feet                                  Source: Wikipedia

As shown in Happy feet, each species have unique song and even little variations are not accepted by peers. 

Special effects:

These songs can also be accompanied with other actions for more impact. 

Western Sandpiper                                          Source: Wikipedia

Western Sandpipers are known for their display flights accompanied with their song. 

A woodpecker drums on a tree while singing. A Ruffled grouse thumps his wings to produce special effects to his song.

Why do they sing?

Though the purpose of these songs can be species specific, they are mostly used to impress mates and proclaim territories.

Who sings?

According to a study, in North America mostly males sing these songs. But in tropics, duets are more common.

Bird on campus:

Not all crows are same!! 

Indian House Crow                                       Source: Wikipedia

 Indian House Crow: Grey neck and smaller size separates it from Jungle crow

Indian Jungle Crow                                       Source: Wikipedia

Indian Jungle Crow: A glossy jet black crow smaller than common Raven

Common Raven                                            Source: Wikipedia

Common Raven: Common Raven is larger than a typical jungle crow and is not so common across subcontinent. It is found usually in desert part of NW India and along Himalayan region.

So next time you see a crow remember that they are all not same!!!

 

'Theory of Mind' in birds

In this post, I wish to introduce you to an interesting concept called ‘Theory of mind’ in birds.

#background -
What is theory of mind? Mind is different from brain and is defined as set of mental faculties which enables your perception, thinking, understanding and judgement. Whereas brain is just physical part of the body. In simpler terms, mind is the outcome of functioning of brain.

In short - 
Theory of mind is the ability to perceive and assign mental states to another individual. Obviously, humans have it and we are here to see if birds have it. Children with autism are shown to lack ‘theory of mind’ to some extent.

Bee eaters, as the name suggests, feed predominantly on insects, bees and wasps. Most of their species are found in Africa and Asia with limited occurrence in Europe and Australia. (Find more about them here).

Small Bee eater                                       Image courtesy: Wikipedia

Bee eaters are shown to avoid nests whenever an intruder is near the nest. It is interesting to note here that Bee eaters are shown to be able to compute the intruder’s scope of vision, line of sight and avoid the nests based on it. This showed that birds have a sense of geometry and that they use that ability to make decisions. These findings were consistent even when it was carried out with two intruders and different line sights with or without obstacles. Bee eaters were able to include the obstacles in line of sight and calculate accordingly. Many such studies have shown similar capabilities in other species as well. You can find the brief version of study here. Interested readers can mail me for further info or clarifications on the same.

This week On-campus bird is

Common Myna                                                          Image courtesy: Wikipedia

Common Myna or Indian Myna is one of the most common species that we can observe in urban environment. These are endemic to SAARC countries but have been recently introduced in Australia, Madagascar and island nations of Indian ocean. 

 

For people interested in bird watching, please buy The Book of Indian Birds by Salim Ali. It is an essential guide for any birdwatcher in India. 

Salim Ali is the ‘Birdman of India’ and a Padma Vibhushan awardee. His life was totally dedicated to birds and is an inspiration to all the ornithology (scientific study of birds) fraternity. Govt. of India established Salim Ali Centre for Ornithology and Natural History (SACON) to honour and pursue his work in 1990.