Kepala seekor burung sengaja diciptakan ringan sehingga hewan tersebut tidak condong ke depan ketika terbang: rata-rata, bobot kepala seekor burung adalah sekitar 1% dari berat tubuhnya.
The bird's head has been deliberately created light in weight so that the animal does not lean forward during flight: on average, a bird's head weight is about 1% of its body weight.