Vervet monkeys shout different warnings for leopards, eagles and snakes
A vervet monkey that spots a leopard gives one call; an eagle or a python triggers another, each sound distinct. Infants pick up these alarms just by watching, and the monkeys even learn which group members tend to cry wolf, tuning out that caller only for the predator it keeps faking.
These black-faced, grizzled-grey primates range across southern and eastern Africa from Ethiopia and the far south of South Sudan down to South Africa, stopping at the East African Rift and the Luangwa River, beyond which the related malbrouck takes over. They live in savanna, riverside woodland, coastal forest and mountains up to 4,000 metres, and cope well with farmland and even towns. People have carried them to islands including Barbados, Saint Helena and Cape Verde, and about 40 live wild at Dania Beach in Florida.
Four hunters are confirmed to prey on them: the leopard, the martial eagle, the yellow baboon and the Central African rock python. Researchers think they may have up to 30 alarm calls, and they have been heard giving a separate one for approaching humans. In experiments with an unreliable caller, the group stopped reacting to that individual's false warnings about one predator but still took its calls about a different predator seriously, suggesting they track both who is calling and what the call means.
Social life is intricate. Troops hold anywhere from 10 to 70 animals. Females stay home for life and inherit rank from their mothers, while males leave at maturity, often with a brother or friend, usually for the next group over. A mother knows her own youngster's scream, and other adults glance toward the right mother when a juvenile cries out. Aggression can even be redirected at relatives of an earlier opponent, hinting that vervets keep track of who is related to whom.
Males are noticeably bigger, averaging 5.5 kg against 4.1 kg for females, and sport a turquoise-blue scrotum. Scientists also use vervets as a model for human biology because they can develop high blood pressure, anxiety and patterns of social and dependent drinking.
Source: Vervet monkey
