Ever since I saw Baloo the Bear [wiki] in Disney's adaptation of Kipling's The Jungle Book, I've always thought bears just like to scratch their backs on trees.
Turns out, they may be doing more than just scratching an itch - they do it to communicate with each other:
Nevin, who will present his findings at the Sept. 10 annual meeting of the British Ecological Society, thinks that by marking the trees with their scent, the male bears get to know each other better, which could reduce fighting among the bears over female mates.
"Big male bears can seriously injure or even kill each other when they get into a fight," Nevin said. "If one recognizes the other from the scent marks on the rub trees in the area, he knows he's in for a tough fight — he's on the other guy's patch so to speak — so it might be better to back away than make a serious challenge."
This species of helminthes/nematode leave eggs in hide not intestinal tract/stool/feces.
And if you know this, you know to stay far away from any site were they perform this activity of scratching.
Eggs of, take a possible 1200 degrees to destroy.
Life expectancy of mature Baylisascaris transfuga a possible 300 years.
diagnostic testing to find infection, none.
Man is a large enough host to allow species to live for about 20 - 25 yrs after being infected.
@ 20-25 yrs burden is large enough to cause man great discomfort.
The fluids released by Baylisascaris transfuga to help in travels through host & others to promote the life of off spring, cause mental problems in man that will make him take his own life or at least make him wish he was dead.
No Joke, No kidding around - I have the Key to this puzzling question .
The idea was that 'display' minimised confrontation.
'back son' should be 'backs on'
Just a heads-up. =D