http://www.freepatentsonline.com/7510722.html
"When the smaller particle is at or below 20 microns, an irritation will occur, causing the bird to cough even more. A cough can only happen inside the birds nasal passage if it is able to fully inhale the chemical so that it penetrates deeper into the nasal passage of the bird. We are utilizing Dr. Vogt's theory of “birds having a very good memory,” posted in 1997. This coughing causes the bird to remember the event at that specific location and not want to come back to the same area."
pirms 14 gadiem
500
Un, vai viņi arī šķauda?
— dzhonsons, pirms 14 gadiem