Armed with some amazing senses and skills, animals can communicate in many different conditions, some of them extreme and challenging. On this page we have picked out some fascinating examples from the environment featured in the programme Forest Worlds.
Forest worlds are alive with animals, all battling to get their message across. But they have to be discreet, as the forest is full of predators, and animals detected by the wrong species can end up as dinner.
Sound travels better than visual messages in the dense forest, which can become deafening at dusk and dawn as birds and primates announce ownership of their territories and challenge rivals. There are many theories to explain why animals sing at dawn. Sound travels well at this time, and it also pays to sing when low light makes hunting unprofitable. Some scientists think that birds are singing off 'extra' energy that they stored in case of a cold night, but want to lose before hunting.
Some animals send messages to their predators, as well as their own species. Tiger moths send an infra-sonic message to big brown bats as they close in for the kill, warning them not to attack. Bats who ignore the message have a nasty shock - the moths are poisonous, and the bats learn not to attack again.
Smell also travels well in the forest. Male arctiid moths send out a chemical pheromone to attract females. When she arrives, the male presents her with a mating gift of a toxin which protects her against spiders. The pheromone sent by the male is based on the toxin. This 'poisonous' message may be to prevent females being attracted to males with no nuptial toxin to offer them.
Plants also use chemical messages in the forest. Cotton plants send out a chemical 'cry for help' when they are attacked by enemies, such as the cotton boll worm caterpillar. This message is picked up by parasitic wasps, who use the trail of scent to find the caterpillars and lay their eggs inside them. The developing wasp grubs stunt the growth and eventually kill the caterpillars. The plant gives off different messages depending on what pest is attacking it, and different wasps use these messages to locate the caterpillars that they are specialised to attack.
Eavesdropping by others of your species can be problematic especially when you suffer an embarrassment. Great tit females listen to singing competitions between their mates and other males. They are far more likely to pay an illicit visit to a neighbour after hearing their mates loosing a contest.
