When a male grizzly rubs a pine tree with his backside, it's not to satisfy an itch but to ward off competition while he looks for a female, according to unusual research.
By leaving his scent on a "rub tree," explained ecologist Owen Nevin of Cumbria University in Britain, a male bear may be seeking to avoid a tooth-and-claw fight with another male on the prowl.
When bears clash, it can lead to injuries or even death, so bark rubbing is a safe alternative to a showdown.
Bear buffs have bared claws in the past over rival theories to explain this unusual behavior.
Some experts have suggested that the tree rubbers are females coming into heat, while others have speculated that the friction could help the bear get rid of parasites or pick up sap as an insect repellent.
But two years of field research observing grizzlies in British Columbia led Nevin to conclude otherwise.
Digital cameras positioned in front of known "rub trees" showed that only males burnished their bottoms on the trees.
And GPS emitters attached to bears tracked by satellite showed that they traveled from valley to valley in large loops, marking trees as they searched for an intimate bear hug from the opposite sex.
"If one male recognizes another 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," Nevin said.
Nevin also noticed that very young bears were also rubbing the bark, leading him to speculate that they might be trying to ward off aggressive males who sometimes kill offspring to mate with the mother. (AFP)
Rose: Where's Colin? I want to meet his new girlfriend.
Clark: He just left. One minute I was talking to his girlfriend, the next moment Colin spilled his wine on her new dress. Then Colin said they should go and wash her dress before the stain sets.
Rose: You must have made him jealous.
Clark: Maybe. But why did he spill his wine on her?
Rose: He was just marking his territory.
mark one's territory 把...佔為己有
To mark one's territory is to claim that place or object for oneself. Dogs and cats often mark their territory by peeing on things. Humans are animals, so it's not unusual to see them exhibit such behavior, too.
「mark one's territory」意指宣示某地或是某物的主權。狗和貓常常會以撒尿的方式來佔領地盤。人類也屬於動物，所以有類似的行為也不令人意外。