View Full Version : Yawning of Asian Openbill Stork

Samrat Sarkar
01-09-2018, 09:30 AM
At the end of the days after completing all our household chores and just before retire to our beds most of us will admit that we cherish the habit of a lengthy yawning. But why only before going to sleep, we often do that when we feel a little relaxed in between spells of hectic periods. And we do that involuntarily. For us humans it is very common to yawn. Not only humans, the apes, monkeys, lizards, tortoises and even some birds also do yawn regularly.

Earlier it was not so easy as the ease with which I declared that the birds also do yawn because the ornithologists did not even think of the birds yawning!

The celebrated ornithologist Heinroth carried out some research works on the changes of behaviours among the different species of the birds. For many decades after that he has recieved many accolades for his contribution in the field of ornithology. The impact of his works was so impressive among the ornithologists that his observations spoke the last word regarding the behavioural studies of the birds. Interestingly, he did not believe that the birds also yawned. And everybody agreed to his views in this regard

Though there have been many research work done and many articles published about yawning in human, no such work has been done worth mentioning about yawning in other animals, mainly among birds. In the year 1967 two ornithologists E G Franz Sauer and E M Sauer published their research paper in the famous ornithological journal, The Auk and in that paper they demanded that the birds do yawn. They conducted their research work on ostriches in the deserts of Namibia, Kalahari, in Erongo Mountain and in Etosha Pan from 1957 to 1958 and in 1964.

I was observing an Asian Openbill Stork in the Mangalajodi wetland in December previous year. It was very close to our boat and was cleaning its feathers with its beak unafraid of our presence. We know this behavior of the birds as “preening”. Some of the very common habitual practices do not generally come to our notice and goes unheeded. Preening is one such behavior of the birds. In the cases of the birds this habit is considered as their comfort behavior.

Simply speaking, during the time the birds feel at home with their surroundings and do not feel any threat from anywhere around that is the time they perform a comfort behavior like this. The bird I was talking about was doing just that and at the end it was standing on one of its two legs. Then it started rubbing its back with the hind portion of its neck.

Samrat Sarkar
01-09-2018, 09:31 AM
At the next moment it made its two large beaks wide open and started yawning.

Samrat Sarkar
01-09-2018, 09:32 AM
If the pictures are arranged successively they will look like this…..

Samrat Sarkar
01-09-2018, 09:35 AM
He slowly raised his head...

Samrat Sarkar
01-09-2018, 09:36 AM
And at the end it again came to its previous position…

Samrat Sarkar
01-09-2018, 09:50 AM
The respected readers may very well ask how I deducted that the bird was yawning and was not doing something else. This is true that there are some limitations in arriving at some specific conclusions out of the mere observations at the birds for a few moments. Even keeping this in mind this particular behavior of the birds may be explained in a new perspective.

Firstly, I was very close to the bird but did not hear any sound coming from it. It was certainly not making any sound.

Secondly, one may think that it was displaying the “open mouth threat-gesture” in anticipation of some impending danger. Now we will go back to the observation that I mentioned in the beginning of my article. Sauer and Sauer have observed that the gular sack contracts upward during open mouth threat gesture whereas it hangs downward during yawning.
If we give a little attention to the picture we will see that the gular sack is freely hanging downwards. If we see minutely in the first picture it will be clear that the tongue of the bird has come out of its mouth to a great extent which might very well happen at the time of open mouth threat-gesture. But it is obvious that the more a bird opens its mouth the more its tongue comes outside in either case of yawning or of open mouth threat-gesture.

Thirdly, the posture of standing of the bird is worth observing. Had it intended to open its mouth this way to give a open mouth threat-gesture it certainly would not remain standing on a single leg in such a careless manner like this, it would have stood on both the legs with sufficient alertness.

Now I will try to describe under what circumstances a bird is more likely to yawn and under what circumstances during my observation the bird opened its mouth this way.

Generally, yawning is a thermoregulatory mechanism which takes place due to the fluctuations of the temperatures of the body or/and the brain. But we know this is hypothesis only. It is the result of some of the successively happening neuro-chemical interaction in the brain. In the case of the birds this is very complicated and very less talked about fact. Recently three ornithologists Andrew C. Gallup, Michael L. Miller, Anne B. Clark carried out research works on Budgerigar .They have discovered that the birds are less likely to yawn under the circumstances of regulated temperatures.

But the tendency of yawning increases as the temperature increases. Again in high temperatures the tendency is coming down and at the same time the gular fluttering increases. Some of us might have witnessed this in cormorants, egrets while they are resting. Gular fluttering is a mechanism of the birds for adapting to the surrounding high temperatures. Therefore it is assumed that yawning is primarily a process of maintaining a balance between the temperatures of the body and the increase in the surrounding temperatures.

Also, yawning is closely related to the physical tiredness. During yawning the birds take long and deep breaths and then exhale which forces the lungs to perform more. The blood circulation to the brain increases. The supply of oxygen to the body increases. The tiredness goes away.

On many occasions the birds are seen to yawn while they are performing some comfort behaviours. They also may yawn before or after preening or stretching during their leisure time. It stopped preening after it yawned and all these activities took place while it was in a restive mood standing on a single leg.

I did not observe the bird for a long period and I had no opportunity to note down the fluctuations of the surrounding temperatures. So it is difficult to decide under which circumstances the bird was yawning. There are some scopes of more research works. The Openbills generally flock in groups. This bird was standing alone in a vast water body. So I did not have any chance to observe its comfort behaviours while it remains in a group. I am telling this for the particular reason that the ostriches remaining in a group are known to start yawning when they see one bird in the group yawning a number of times.

Yawning acts as a social stimulus among them. So, it is obvious that to maintain a balance of their body temperature with their surrounding temperature and to express a feeling of security with some comfort behaviours in their surroundings they may yawn.

When the ostriches take rest they have been seen to yawn just after overcoming some small dangers and to go to rest again. We cannot strike out this logic in the case of this Openbill because it was obviously in a condition of resting as it was standing on a single leg and primarily might very well have taken our large boat for a possible threat. Whatever may be the reasons, we yawn and the birds yawn as well, and this is a proven truth now.

Papers cited:-
1. Yawning and other maintenance activities in the South African Ostrich by E. G. Franz Sauer and E. M. Sauer.
2. Yawning and thermoregulation in budgerigars, Melopsittacus undulates by Andrew C. Gallup, Michael L. Miller, Anne B. Clark.

Written in Bengali and photographed by Samrat Sarkar.
Translation into English by Biswajit Debnath

This article has already been published in a National science Magazine. Although I am sharing this article in this forum for wider portion readers, researchers and naturalist and activist. I have done many such observations and documentations in the wetland of Mangalajodi and Chilika. Chilika has huge biodiversity. The Chilika lake and Mangalajodi wetland is now under serious threat as a Seaplane project will be executed there which will have enormous adverse impact on the fragile ecosystem of Chilika as well as Manglajodi. Many of such beautiful species will disappear from Mangalajodi permanently. Please raise your voice against Seaplane project.


Mrudul Godbole
04-09-2018, 09:05 AM
Especially in the second photograph (Part II), the facial expressions and the open beak with the visible tongue does seem like it is yawning. Very detailed observations and lovely photographs to supplement them. Thanks for sharing.

Samrat Sarkar
22-09-2018, 10:11 PM
Thanks a lot Mrudul ji.. You have always inspired me....


Saktipada Panigrahi
05-10-2018, 08:16 PM
Samrat Bhai
You have undertaken in-depth study and your observations will strengthen parallel study or throw new light in areas hitherto unknown.
You are also drawing sketches of birds for some book. Well, for conversant people or research papers elaborate drawings are necessary , but for wider audience side by side photographs are useful or not you are a better judge.
Thanks for sharing. SaktiWild