Of course, humans are not the only creatures with the ability to communicate. Although governed more by instinct, animals also have some remarkable forms of communication. For example, courting emperor penguins in icy Antarctica go through their annual prewinter ritual of hooting at each other​—but not for fun. The life of each couple’s future chick is involved. How so?

After laying her egg, the female releases it to her mate to incubate in his brood pouch while she goes to sea to feed. About 65 days later, she returns, having waddled and slid on her belly across the ice for up to 100 miles [150 km]. Finding the colony is a miracle in itself, but how does she find her mate and their newly hatched chick among tens of thousands of hooting emperors? During their courtship each bird memorizes the other’s songs so well that even after months of separation, they manage to find each other!

In addition to a phenomenal variety of sounds, animal communication includes gestures, attention-grabbing colors, flashing lights, and complex scents.

Communication in the World Around Us

“Without communication, each individual would merely be an island isolated from all other such islands.”​—The Language of Animals.

IN A patch of forest, a savanna, or even in your own garden, any number of animals might be busily communicating with one another. The book The Language of Animals says: “Animals use every sense, gesturing with appendages and body position; sending and receiving subtle​—or not so subtle in the case of frightened skunks—​odor signals; squeaking, squawking, singing and chirping; sending and receiving electrical signals; flashing lights; changing skin pigmentation; ‘dancing;’ and even tapping and vibrating the surface they walk on.” But what do all these signals mean?

Scientists discover the meaning of animal signals through careful observation. For example, they have observed that when a bantam (small domestic fowl) sees a ground predator such as a weasel, the bantam makes a high-pitched kuk, kuk, kuk sound to warn other bantams. But if it spots a hawk, a bantam emits a single long shriek. Each call elicits a prompt response that accords with the threat, indicating that the birds communicate meaningful information. Other birds have been observed making similar discriminating calls.

“One of the main ways to study communication in animals,” says the book Songs, Roars, and Rituals, “is to record the signal of interest and then play it back to the animals and see whether they respond in a predictable way.” Tests with bantams gave the same results as were observed in the wild. The method works even with spiders. In order to determine what attracts female wolf spiders to courting males​—which try to impress females by waving their hairy forelegs at them—​researchers experimented by videotaping a male wolf spider and digitally removing the tufts of hair from its legs. When they played the video back to the female, she suddenly lost interest. The lesson? Female wolf spiders are evidently attracted only to males waving hairy legs!

Signaling With Scent

Many animals signal one another by secreting powerful chemicals called pheromones, usually from special glands, or by means of their urine or feces. Just as a fence and a nameplate or number identify the property of a human, pheromones flag and define the territory of certain animals, including dogs and cats. Although invisible, this most effective form of marking enables animals of the same species to keep an optimal distance from one another.

But pheromones do more than mark territory. They are like a chemical bulletin board that other animals “read” with great interest. Scent marks, says the book How Animals Communicate, “probably include additional information about the resident, such as its age, sex, physical strength and other abilities, [and] the current phase of the owner’s reproductive cycle . . . The scent of the animal’s mark acts as his passport for individual identification.” Understandably, some animals take their scent marks very seriously​—a fact well-known to zookeepers. After washing down cages or runs, keepers have observed that many animals immediately remark their area. Indeed, “the absence of its own scent is stressful and may evoke abnormal behaviour and even sterility,” says the above reference.

Pheromones also play a big role in the insect realm. Alarm pheromones, for example, mediate swarming and attack behavior. Aggregation pheromones attract individuals to a food source or to a suitable nesting site. They include the sex pheromones, to which some creatures are acutely sensitive. Male silkworm moths have two elaborate antennae that look like tiny, delicate fern fronds. These antennae are so sensitive that they can detect a single molecule of female sex pheromone! Some 200 molecules will cause the male to begin searching for the female. Chemical communication, though, is not confined to animate life.