Elephants have recently been seen blocking a highway often used by produce trucks in Thailand that runs through the Ang Lue Nai wildlife reserve. Produce truck drivers say the animals head-butted their vehicles when they could not get to the goods they were carrying. "Sometimes the whole elephant herd, six or seven of them, stand in middle of the road... some of them try to pull sugar canes from the lorry, when they can not, they just break the wind shield," said driver Puern Meksan. Officials at the natural reserve have imposed a dusk-to-dawn curfew on the road.