He got a metal shovel and hit the stone sides of the house so that the noise would warn the birds and animals of danger.
VOA: special.2010.03.20
Other products warn drivers if they are falling asleep or in danger of an accident.
VOA: special.2010.01.08
According to Dr Sinclair's theory, which he calls xenohormesis, animals rely on such botanical stress signals to give them extra information about their own environments, in the same way that the alarm calls of one species warn others ofdanger.