Complex sentence: These down feathers differ from the usual down as they are exceptionally fine and produce a dust between the frons, the bird takes this dust from its powder down feathers and coats all its external feathers with the dust.
Split into simpler sentences: These down feathers differ from the usual down as they are exceptionally fine and produce a dust between the frons. The bird takes this dust from its powder down feathers and coats all its external feathers with the dust.