Assalamu alaikum wa rehmatullahi wa barakatuh
Do they not see the birds above them with wings outspread and [sometimes] folded in? None holds them except the Most Merciful. Indeed He is, of all things, Seeing.(Mulk 19)
The flying birds,and none holds them except the Most Merciful !!!
The words in the verse are specifically that THE MOST MERCIFUL holds them.
Now some facts regarding their flying ability.
Streamline shape is the special shape which offers least resistance by the air or water to allow easy and fast movement in the medium.
The least drag coefficient is for the streamlined body.The birds are designed by Allah in a streamline fashion to offer least resistance while flying.
Fishes have the same streamlined shape which allows them to swim easily and the aeroplanes are also designed in the same way to fly with least air resistance.
The metal sinks down in a water tub due to its density,and the cork floats because it has air spaces in it,it is less denser than the metal.
Allah has made the skeletal bones of the birds hollow,their density is decreased by pneumatizing them (pneumatized bones contain air spaces).This decreases the density of the bones and enable the birds to fly.
There are many air sacs placed inside the body of the birds,to make them lighter,to enable them to fly.
Heart is four chambered and larger than the mammals in relation to body size and mass.
The hearts also tend to pump more blood per unit time than mammalian hearts. In other words, cardiac output (amount of blood pumped per minute) for birds is typically greater than that for mammals of the same body mass. Cardiac output is influenced by both heart rate (beats per minute) and stroke volume (blood pumped with each beat). ‘Active’ birds increase cardiac output primarily by increasing heart rate. In a pigeon, for example (Butler et al. 1977):
|Heart rate||115 beats/min||670 beats/min||5.8x|
|Stroke volume||1.7 ml||1.59 ml||0.9x|
|Cardiac output||195.5 ml/min||1065 ml/min||5.4x|
|Oxygen consumed||20.3 ml/min||200 ml/min||10x|
The oxygen is needed more at higher altitudes,and thus the respiratory system is designed accordingly.
The lungs are interconnected with a system of large, thin-walled air sacs in the front (anterior) and back (posterior) portions of the body. These, in turn, are connected with the air spaces in the bones.
A bird’s respiratory system is proportionately larger and much more efficient than ours — as might be expected, since flight is a more demanding activity than walking or running. An average bird devotes about one-fifth of its body volume to its respiratory system, an average mammal only about one-twentieth.