photo feature Yawning of Samrat Sarkar

E yawn when we are sleepy, tired or plain simply The stork also seemed comfortable. But the very next bored. Yawning comes to us involuntarily. But did moment it opened its two large beaks wide open and started Wyou know that apes, monkeys, lizards, tortoises and yawning! even some also yawn? Now, the readers may very well ask how I deduced that the Celebrated ornithologist Heinroth who carried out was yawning and was not doing something else. Firstly, I extensive research on different of the birds, did not was very close to the bird but did not hear any sound coming believe that birds also yawned. However, in the year 1967 two from it. It was certainly not making any sound. ornithologists E.G. Franz Sauer and E.M. Sauer published their Secondly, we may presume it was displaying the “open research paper in the famous ornithological journal, The Auk in mouth threat-gesture” in anticipation of some impending which they asserted that birds do yawn. They conducted their danger. Sauer and Sauer have observed that the gular sack research work on ostriches in the deserts of Namibia, Kalahari, contracts upward during “open mouth threat gesture” whereas in Erongo Mountain and in Etosha Pan from 1957 to 1958 and it hangs downward during yawning. Take a look at the picture in 1964, respectively. closely and you will see that the gular sack is freely hanging Some time back I was observing an Asian Openbill Stork in downwards. the Mangalajori wetland. It was very close to our boat and was The posture of standing of the bird is also worth observing. cleaning its feathers with its beak unafraid of our presence and Had it intended to open its mouth this way to give an “open was standing on a single leg. We know this behavior of the birds mouth threat-gesture” it certainly would not remain standing as “preening”. When birds feel at home in their surroundings on a single leg in such a careless manner; it would have stood that is when they perform a comfort behaviour like this. on both the legs with sufficient alertness.

34 | Science Reporter | June 2018 Now, let us see under what circumstances a bird is more During yawning the birds take long and deep breaths and likely to yawn. Generally, yawning is a thermoregulatory then exhale forcing the lungs to perform more. The blood mechanism which takes place due to the fluctuations of the circulation to the brain increases. The supply of oxygen to the temperatures of the body or/and the brain. But we know this body increases. The tiredness goes away. is a hypothesis only. It is the result of some of the successively On many occasions the birds are seen to yawn while they happening neuro-chemical interactions in the brain. In the are performing some comfort behaviour. They also may yawn case of the birds this is very complicated. Recently three before or after preening or stretching during their leisure time. ornithologists Andrew C. Gallup, Michael L. Miller, Anne The bird I was observing stopped preening after it yawned B. Clark carried out research on the Budgerigar. They found and all these activities took place while it was in a restive mood that birds are less likely to yawn under the circumstances of standing on a single leg. regulated temperatures. Ostriches in a group are known to start yawning when they But the tendency to yawn increases as the temperature see one bird in the group yawning a number of times. Yawning increases. At higher temperatures the gular fluttering increases. acts as a social stimulus. When the ostriches take rest they have Gular fluttering is a mechanism of the birds for adapting to been seen to yawn just after overcoming some small dangers the surrounding high temperatures. Therefore, it is assumed and to go to rest again. that yawning is primarily a process of maintaining a balance Written and photographed by Samrat Sarkar, Village-Majdia, Post between the temperature of the body and the increase in the Office-Madanpur, District-Nadia, West Bengal-741245; Email: surrounding temperature. [email protected] Also, yawning is closely related to physical tiredness. Equipment used: Canon EOS 7D + Canon 500mm f4 + Monopod.

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