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.

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