Mobbing calls are signals made by the mobbing species while harassing a predator. Workplace bullying is sometimes termed "mobbing". Buffaloes engage in mobbing behavior when fighting off predators. For example, many gull colonies display mobbing behavior, attacking and harassing predators and other intruders. Hosts attack cuckoos more when they see neighbors mobbing cuckoos. They are unusual among parrots in engaging in mobbing behaviour against predators. The video depicts a young male student facing mobbing and harassment from his schoolmates. The collective force of a group mobbing predators can reduce risk of predation significantly. "Mobbing", carries a more negative connotation associated with bullying. Its voice becomes harsher when alarmed, and it shrieks loudly when mobbing predators. Mobbing behaviour is often seen in birds. Groups of dolphins have occasionally been observed defending themselves from sharks with mobbing behaviour. Spotted hyenas have adapted by frequently mobbing lions that enter their territories. Spotted hyenas have adapted to this pressure by frequently mobbing lions which enter their territories. Sociologists and authors have created checklists and other tools to identify mobbing behaviour.