Our health, physique and physiological responses to our environment can influence how we communicate, and how others interpret us. Take feather position in parrots as an example.
The control mechanisms of feather movements are much more complex than that of the hair in mammals. There are many different tissue layers and individual muscles involved, and it appears as though the follicle (where the individual feather is attached in the skin) can, at least on some parts of the body, often be controlled both by involuntary (reflexive, like when you get goose bumps) and voluntary mechanisms. Much like how you blink reflexively most of the time, but you can also blink as a controlled movement. So, changes in feather position can, to the best of my knowledge, likely be both a conscious as well as a reflexive response to certain environmental events or conditions.
Feathers, apart from being used in flight and signalling, are also important for the regulation of body temperature in parrots. Birds will often tighten their feathers when warm and relax or erect them when chilly. This means we need to keep these environmental variables in mind when we are interpreting body language. If it is cold or a parrot is very tired or even sick, chances are some body language cues might look differently than they would in the same bird when it is warm and active, or not be observable at all.
In a similar way, the appearance of some body language cues can be influenced or masked by the physical condition an individual bird is in. Poor feather condition or missing feathers due to feather destructive behavior or illness can make it difficult to accurately spot changes in feather position. It can be more difficult to spot postural changes in an extremely obsese parrot. Parrots with clipped wings, arthritis, pain or other physical disabilities and conditions might move very differently than a healthy, fully flighted bird.
4.2 LET'S GET PHYSICAL
This young blue and gold macaw has been subjected to a very severe wing trim. Apart from affecting the bird's general health and wellbeing, this will also influence the appearance of signalling that involve the wings. Changes in balance, coordination and other factors that are influenced by wing clipping might also influence the body language of this bird as compared to a fully flighted conspecific. To the right is a very rough sketch of what the outline of the wing might have been had the bird not been clipped.
It is my personal belief, based only on my own observations, that certain kinds of pain and other health conditions that might influence the appearance of posture and movements in parrots are likely underdiagnosed in pet- and aviary birds. Whereas most pet owners and veterinarians familiar with dogs would be more likely to recognize when a dog is stiff or experiencing pain, my observation is that this is far from always the case when it comes to parrots. I've often had the very opposite experience where, for example in clients contacting me for help with recall training an older bird, the owner will not even consider the possibility that the stiff, slow moving parrot with an abnormal wing conformation might in fact not be doing well with recall training because it is physically uncomfortable.
As we are becoming better at noticing and diagnosing pain, understanding the effect it can have on behavior as well as preventing- and trating it in other species like dogs, I can only hope the same trend will take effect in the world of birds and other exotic species under human care.
Body condition scoring (BCS) of parrots usually requires a physical examination. In extremely obese birds however, like this galah, the body condition can easily observed from afar. As a result of obesity the galah has a wider stance, and the abdomen is large enough that it touches the branch as the bird is perching. As a result this bird will have a different posture than a galah with a healthy weight.
Being very familiar with the body language of healthy parrots in general as well as what changes in body language can arise from pain and other health conditions is very important for anyone taking care of parrots, in any capacity. It is also very important to familiarize ourselves with what a normal body language is for the particular individuals we are caring for. Not just because it helps us interpret that body language better, but also because it can help us notice impending health issues faster. Advice that I often give especially to owners of parrots with chronic health issues, but also recommend anyone caring for animals in general do, is to regularly record video of the animal as it moves as well as photograph's of it's posture during rest. If we interact with an animal daily it is much more difficult to notice the often very gradual changes. Being able to compare a bird's current condition with previously recorded material of the same individual can greatly increase the chances of noticing any changes, good or bad, that accumulate over time.
Homberger, D.G. & de Silva, K.N. (2003) The role of mechanical forces on the patterning of the avian feather‐bearing skin: A biomechanical analysis of the integumentary musculature in birds. J. Exp. Zool., 298B: 123-139.
Levinger, I.M., Angel, S. & Hyams, M. (1985) Possible control mechanisms of feather follicle movement in the pectoral tract of the chicken. Vet Res Commun 9, 153–162