Sentinel behaviour and the watchman\'s call in the Chukar at St Katherine Protectorate, Sinai, Egypt

Abstract

Foraging in a group potentially allows individuals to reduce anti-predator vigilance
without increasing predation risk. Individual vigilance may be further reduced if group
members take turns at watching for predators, acting as sentinels or guards. Because the
presence or absence of sentinels must be monitored to ensure that the group is guarded at
all times, the conditions favouring the evolution of coordinated vigilance are probably
very specific. We studied groups of chukars, Alectoris chukar (Gray, 1830)
(Phasianidae), a desert species reported to adopt a sentinel system, to see whether this
was the case. Individuals identified as sentinels behaved significantly differently from
other group members, occupying prominent positions and being vigilant significantly
more than foraging group members. The largest individuals became sentinels most
frequently, yet were not more vigilant than smaller individuals while they were on guard.
Sentinels that ended a bout of vigilance were usually replaced quickly; a soft call was
heard during a significant number of exchanges. We conclude that chukars do have a
sentinel system of vigilance. A vocalisation, similar to the watchman\'s call seen in other
species, seems to play a role in coordinating vigilance behaviour.

Keywords: anti-predator vigilance, flocking,

Egyptian Journal of Biology Vol. 10 2008: pp. 42-53