We learn that this word is onomatopoetic, less noisy than “flacker”.  Both have to do with the motion of bird wings, at least in their first meanings.

• 01.071 the firelight flickered –
• 07.094 and the fire flickered about them,
• 08.006 in the little flicker of the flames.
• 09.039 and the flicker of lights.
• 12.029 Flickering fires leaped up
• 13.019 it was tinged with a flickering sparkle
• 14.003 Suddenly it flickered back to view;
• 17.050 and each flickered as it fled as if with stinging fire.

“flicker, v.” OED Online. Oxford University Press, June 2015. Web. 26 July 2015.