When a friend and “crow expert” told Katsufumi Sato to hang some “do not enter signs” on the outside of a building to keep pesky crows a way, the Japanese professor thought he was only kidding, but after three years of employing the bizarre strategy, he says it works perfectly.
Sato, a professor of ethology, hanged his first “crows do not enter” signs at a university research center in Otsuchi, Japan’s Iwate Prefecture, in 2015, at the the advice of his friend, Tsutomu Takeda, who he regards as an expert on crows. The birds had been targeting the insulation material covering the building’s pipes, ripping it with their beaks and flying away with bits of it to use for their nests. He was desperate to keep them away, so even though he though the idea of hanging written signs for crows funny, he was willing to give it a try.