Communication using chemicals

Different smells that we are able to detect are nothing but chemicals. Bearing in mid that animals’ olfactory system is far better developed than that of humans, it is understandable how animals are capable of detecting different scents at great distances. While some of these smells may seem unimportant or undefined to us, for animals they can be of great importance since they may carry vital information regarding a food source or a female ready to mate. These chemicals that we detect as different smells are called pheromones. Pheromones may be used for various purposes, which include marking the territory and mating markers.

Marking the territory is very important in the animal world. The territory represents the area where an animal or a group of animals reside. Limiting the boundaries of their territory is very important to animals and they use the so-called “scent markers” to do this. Namely, limiting the territory reduces the number of conflicts between the members of the same species. Also, this makes it easier to hunt for food, provide a water supply and mate. The male who possesses a larger territory is more likely to impress a female and mate with her.

Animals usually use their feces for marking their territory because they have very powerful pheromones in them. “For example, rabbits and deer will frequently leave a strategically placed pile of feces on a flat rock that marks the boundary of their territory. Male mountain lions will often create a scent post by using their hind legs to kick up a pile of leaves or pine needles. After they have built this visual marker, they leave their scent by urinating on it.”¹

Beside feces, some animals have scent glands on different parts of their body and will simply rub against a tree or a rock in order to mark their territory. They also rub against other animals, usually their offspring or their mates, in order to let the others know that that particular individual belongs to them. “This behavior can often be seen in house cats. Many people think it’s a sign of affection when a cat comes over and starts rubbing its head against them. The cat may like you, but it has another motive. Cats have scent glands all over their faces. When they rub up against you, they are really spreading a chemical message that you belong to them.”²

Apart from visual displays and mating calls, another technique that animals employ in order to attract a mate is the use of mating markers. “Some male mammals use musk as a pheromone to mark territories. They also use it to signal to females that they are ready to mate.”³ According to the strength of this pheromone, the musk, a female will choose the most powerful male to mate with. In order to attract a female, males use various techniques for spreading the musk. For example, “a male rhinoceros will roll around in his own urine and wear it like cologne. A male hippopotamus will wave his tail back and forth past his anus, where his musk glands are located. This spreads the scent of the musk through the air.”⁴

Likewise, females send out their pheromones to signal to the males they are ready to mate. “Sometimes the chemical is released in the air and sometimes it’s mixed with her urine. Either way, when the male picks up the signal, he knows that he has only a short time to act.”⁵ Elephants can serve as a good example of such behavior. Namely, “a male elephant has a unique way of telling whether a female is in estrus or not. The male elephant will follow the female until she urinates. Then he dips the tip of his trunk into the liquid and touches it to the roof of his mouth. This is where his vomeronasal organ is located. if the female elephant is in estrus, a pheromone will send a signal to the male elephant’s brain that will cause nitric oxide to be produced in his blood. This chemical stimulates the male elephant, allowing him to mate. If the female is not in estrus, nothing happens.”⁶

1 Stephen M. Tomacek, Animal Behavior: Animal communication, 2009. Infobase Publishing, p. 42

2 Stephen M. Tomacek, Animal Behavior: Animal communication, 2009. Infobase Publishing, p. 42

3 Stephen M. Tomacek, Animal Behavior: Animal communication, 2009. Infobase Publishing, pp. 43-44

4 Stephen M. Tomacek, Animal Behavior: Animal communication, 2009. Infobase Publishing, p. 44

5 Stephen M. Tomacek, Animal Behavior: Animal communication, 2009. Infobase Publishing, p. 44

6 Stephen M. Tomacek, Animal Behavior: Animal communication, 2009. Infobase Publishing, p. 44