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Thread: A few words on the mutual courtship dance of Silver-breasted Broadbill

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    Default A few words on the mutual courtship dance of Silver-breasted Broadbill

    The name of the bird is Silver-breasted Broadbill. They are endemic in the forests thickly covered with vegetation canopy. After the Bengal Florican, these are the most sought after birds in the Manas National Park. Many tourists visits Manas to watch these birds. This female bird in the picture here is sitting unconcerned in a dreamy surroundings of yellow green lights. Please notice that there is a white circular ribbon round the neck of the female birds.

    Some recent findings declare that there are not only the yellow-green lights in the forests, but at least five different types of lights prevail in different situations there. They are 1. Yellow-green, 2. Bluish-grey, 3. Reddish-orange, 4. Bluish-violate, 5. Pure-white. The type of light depends mainly upon the geometry of the forest, upon the presence of the clouds in the sky and upon the angular position of the sun in the sky. Generally the bluish-grey lights are seen in the forests in most situations; when there are some opennings in the jungle reddish-orange lights are seen; when these openings become quite large the light becomes dull white with or without the presence of some clouds in the sky; the light becomes bluish-violate in early mornings and just before the darkness comes at night; and in the forests covered by a roof of thick vegetation the yellow green light becomes prevalent. These interesting findings were disclosed in the research paper of Mr. John A. Endler, a researcher in the California University. He also claimed that the presence of these different types of lights are not dependent on the diverseness of the trees of the forest, or on the heights of the forest nor on which continent the forest is situated.

    All these are about the tricks of the different available lights which determines the different settings of the camera required for a better picture. But do these different lights influence the moods of the birds that I am trying to capture through my lens? As per Mr. Endler, yes! But what sort of influence do they play?

    The Manas National Park has long been enticing and enthralling the tourists with the splendorous of its diversified landscapes of vast dry riverbeds, deciduous forests, rising slopes of the hills, long stretches of grasslands and with its vast expanse of wetlands. As we go past the long and grassy wetlands at the foot of the Bhutan hills on the north west of the Park we enter the canopy of the vast evergreen forest. Due to this variety of its topography and geography the Manas has produced a large variety of flora and fauna.

    It takes a lot of hard work and trouble as a photographer to take pictures of these landscapes in such difficult situations and mainly while photographing birds. The main reason of this is ever changing of available lights. The settings of the camera have to be changed every time the lighting situations change. There are no scarcity of light in the dry river beds or in the the grasslands, but the moment we enter into a deciduous forest the light starts playing hide and seek with the camera. Photographing in the evergreen forests covered by thick layers green leaves at top are more difficult than any other places. Here nobody knows from where the light will come. In most cases the sun rays hardly penetrate the thick leaves at top, and when it comes at times it backlights the outlines of the birds and in situations like this the pictures of the birds become underexposed in the yellow-green background of the trees.
    Please see the yellow-green background.
    The female
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    Last edited by Mrudul Godbole; 24-07-2020 at 01:12 PM.

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    Default Part 2

    I have said that the different phases of time create different spectral environments in the forest. There are a number of birds who display the colours of their feathers in different manners to lure and to select their prospective mates. These colours of their feathers blossom differently in different spectral environment of the forest. The reflectance spectra of their feathers in a suitable ambiance greatly appeal their mates. Thus we may infer that a successful courtship to a great extent depends on the geometry of the forest, on the presence of clouds in the sky, on the angular position of the sun in the sky mainly for the birds who capitalise on the attractive colours of their feathers to attract their partners by courtship display. This is what the researchers, Mr Endler and Mark Thery have disclosed in their another research paper in the year 1995. Therefore, the colourful feathers of the birds or the difficult manoeuvre they perform to attract their partners get greatly stifled unnless there is a suitable, dramatic and ambient spectral environment around them in the forest.

    Let me come back to my topic again about the Manas and the bird. The female bird was at first sitting alone in a branch of tree. The male one at that moment was sitting on another branch of tree.

    The male
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    Default Part 3

    Suddenly the female bird flew away and sat on another branch where the ambiance of the yellow green colour was more prominent. It was not known whether there was some signal from the female bird to its partner, the male bird did not waste a single moment to move near the female one and sat very cose to its partner (as seen in the picture)
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    Default Part 4

    Then I was became a witness of a marvelous series of events. The male bird brought its tail a bit downwards and spread its wings to some extent and started dancing beautifully.
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    Default Part 5

    The female bird was watching its partner and then she also spread its wings the same way as the male one was doing.
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    Default Part 6

    The male bird started raising its tail upwards slowly and started moving its wings forwards from backwards.
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    Default Part 7

    The female partner then started doing just the same; moved the wings forwards from backwards. The two birds seemed to be just like two expert swimmers doing butterfly strokes in a same rhythm in yellow green ocean of water. The female bird pointed its face towards the sky feeling contented.
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    Default Part 8

    This is the intrinsic mutual courtship dance of the Silver breasted Broadbill and usually last only for 12 to 15 seconds.
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    Default Part 9

    No sooner had the dance ended than the female bird turned its face towards its partner and looked at him.
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    Default Part 10

    The next moment the male bird mounted on the back of its partner with an intention for copulation.
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    Default Part 11

    The Silver breasted Broadbill spends its lifetime under the covered canopy of the evergreen forest and naturally they mate in these places only. In those forests under covered canopies very small amounts of light penetrate from the open sky to the ground. And whatever amount of light comes it does so after being reflected by the green leaves and for that reason the surrounding atmosphere becomes filled with yellow green hues. From these findings we can make some general conclusions.

    Discussions and conclusions -

    1. Both the birds were sitting on two different well lit and airy tree branches. But at the time of mutual courtship dance both of them came to a branch which was obscured by some leaves. Mr. Endler and Mr. Thery observed that the birds prefer only those lighting situations where the colour of their feathers become cryptic, dramatic and conspicuous while at the same time they can camouflage to save themselves from the threats of the possible unknownenemies. In this case also those factors might have played some important roles.

    2. There are many and different colours in the body of a Silver breasted Broadbill. Among all these colours the most attractive ones are the liver-hued red patches extending from beneath the back upto the mid portion of the tail, and two distinct of sky blue and white patches in their black wings. The visions of the birds are much more sensitive than ours’ and they can differentiate the subtle variations of lights. They might have spent thousands of years to learn this special type of mutual courtship dance in which they want to display their beautiful colours on their feathers more prominently to their partners. That may be the reason why they want to expose more the colourful beauty patches on their wings and backs to their prospective mates.

    3. The particular branch of tree might have been used for this particular purpose of courtship activities by their contemporaries or even by their forefathers for past few years. In the language of ornithologists this type of places are called as Lek place. This couple also have made a good and proper use of this place.

    4. In this connection let me remember that I observed a pair of Orange headed Thrush (OHT) in our village one year ago. https://www.indiawilds.com/forums/sh...-headed-Thrush. In the case of that pair also I observed more or less the same type of behaviour as that of the present pair. Reddish orange colour of sunrays made their way through some small openings of the tree leaves above and fell on the dry leaves on the ground. In situations like this the sun rays after passing through the small openings fall directly on the ground. The sunrays make an angle with the horizontal as it passes through the small holes between the leaves above, the same angle as we look at the sun. In situations like this the lights of long wavelengths, such as red and orange become prevalent suppressing the other colours. After observing the particular pair for a number of times I could pretty well identify the pair at a glance. The female bird was bringing food stuff from the male one and was again and again coming to sit and spread its wings on that particular spot where sunrays were coming. It was obvious that the bird was spreading its wings not for baking in the sun because it was mid noon and was in the month of April and the temperature was around 38 degree Celsius. Had the bird wanted to bake in the sun it would have remained sitting under the sun at the same spot and would not have left the spot again and again.
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    Default Part 12

    The head of the bird was bright orange. The bird was perhaps eager to show to its partner how bright and colourful its body was in the background of the orange light and liver hued dry leaves. The male bird was hopping around its partner with some hay stuff in its mouth intended for building their nest.

    All around the world there are a number of species of birds the females of which display the beautiful colours of their bodies to their male counterparts.M. Susan DeVries, Caitlin P. Winters and Jodie M. Jawor in their research paper in year 2014 shown that a female Northern Cardinal was singing and dancing for its male partner the same way as a male sings and dances. Here also the female OHT is displaying courtship to the male bird by successfully banking on the reddish orange colour of the sun rays and the light liver hued colour of the dry leaves. The male bird also became satisfied that it had made no mistake to choose a suitable mate. And this resulted in a successful conjugal mating season.


    These are the interesting relations of the role of different lights in the forest with display activities of the birds. And the joint courtship dance of the monogamous birds like the Broadbills is not anything less interesting either.

    There are more than 200 species of birds in the world which perform courtship song and dance and display other courtship activities. Some of them are polygamous and the others are monogamous. In the case of the Broadbills in the picture here we can come to some inferences based on the observations

    1. I did not hear either of the birds to sing for the other though the Silver breasted Broadbills are capable of singing in a loud voice and many monogamous birds like them sing songs to attract their partners.

    2. There may be many number of reasons for mutual courtship dances. It may be intended for selecting a suitable partner or may be to reinforce their conjugal relationship or may be for demarkating the area under their control. There has not been any proper research in this field so far. All the minute details of sole display or of mutual display are really very difficult to understand and the amount of information we have gathered in this field are mainly based on speculations only. There was another male bird close to this couple. The courtship dance that the male bird started displaying might be to prove to the second male bird the strength of their conjugal relationship with its partner.

    3. There is a term in ornithology; CSD. Its full form is“Copulation solicitation display”. At the end of the mutual courtship dance the female bird gives a signal to the male bird. The male bird reads the signal correctly and understands that its partner now has given him permission to mount. This very signal of the female bird is known as the CSD. In the picture the female bird gives a distinct glance at its male partner after which the male bird mounts. Thus it may be concluded that this that such sideways glance of the female bird is another name of CSD.




    Equipment used - Canon EOS 7D + Canon 500 f4 IS II
    Place of observation -Manas National Park
    Date of observation – 02.04.2018

    Behind the female, the male was hopping with some nesting materials in his beak..
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    Interesting theories. Often it becomes difficult to realise that there is a courtship dance going on as these are brief. If you are able to sight a few more such mating behaviours of the same species as well as other species then the sample size will improve and we can then find sufficient data to predict with confidence. Just mention the date, time place of the observations so that we can refer back later.

    At roughly what height in the canopy was this mating? Thanks for sharing.

    Cheers,
    Sabyasachi

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    Lucky you could observe this courtship dance and also could photograph it. It lasts only 10-15 seconds, not many would be able to even comprehend that it was a courtship dance which happened. One has to be so alert and observe closely to understand the natural history. You have done it wonderfully. Thanks for sharing such detailed information on the species and its behavior.

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