A sentinel system in the Florida scrub jay

McGowan, Kevin J.; Woolfenden, Glen E.

doi:10.1016/0003-3472(89)90144-9

Cited by 158 publications

(131 citation statements)

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“…This system in turn is due to selfish reasons that depend on the internal state of mind of each sentinel animal in question to ensure their own benefit. Moreover, coordinated vigilance shifts or changing of guards are frequent in this type of vigilance, with little variation in the number of sentinels involved and with a high replacement frequency [17]. In this case, the number of sentinels remained invariable in all incursions.…”

Section: Discussionmentioning

confidence: 98%

Vigilance by Sentinels in a Group of Baboons (Papio hamadryas hamadryas) in a Zoo Setting

M¹

2014

J Primatol

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Vigilance by sentinels is an anti-predator strategy by which certain group members keep watch from strategic positions, while the group is involved in other activities. Many anti-predatory behavior patterns observed in natural habitats are also deployed similarly when provoked by human presence. This work is part of a study conducted with a group of hamadryas baboons (Papio h. hamadryas) in semi-freedom in a 15-hectare zoo complex with extensive human pressure. The animals make incursions into an adjoining high-risk area to access food resources, making use of vigilance with sentinels and other risk minimization strategies. Results reveal that human presence provokes similar reactions to natural predatory pressure, forcing them to select strategies to minimize the factors involved in risk perception, such as the degree of visibility of the surroundings, minimizing the length of the incursion and behavioral restrictions.

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Section: Discussionmentioning

confidence: 98%

Vigilance by Sentinels in a Group of Baboons (Papio hamadryas hamadryas) in a Zoo Setting

M¹

2014

J Primatol

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“…Among some advantages of living in groups, birds may benefit from the enhancement of protection from predators mainly due to better surveillance (Pullian, 1973), as verified empirically in some studies (Powell, 1974;Bertram, 1980;Elcavage & Caraco, 1983;McGowan & Woolfenden, 1989). Sentinels (i.e.…”

Section: Introductionmentioning

confidence: 84%

“…Sentinels (i.e. individuals that interrupt foraging for extended periods to watch for predators) have been identified in many bird species (Andrews & Naik, 1970;Gaston, 1977;Wickler, 1985;Verbeek & Butler, 1981;Ferguson, 1987;McGowan & Woolfenden, 1989;Alves & Cavalcanti, 1996). Actions such as guarding other individuals, alerting them to danger, and an alternation of guarded periods to avoid vigilance overlapping are pointed as remarkable features to evaluate sentinel behavior as an adaptive device (McGowan & Woolfenden, 1989).…”

Section: Introductionmentioning

confidence: 99%

“…Actions such as guarding other individuals, alerting them to danger, and an alternation of guarded periods to avoid vigilance overlapping are pointed as remarkable features to evaluate sentinel behavior as an adaptive device (McGowan & Woolfenden, 1989). Because sentinels improve the group's vigilance, by increasing perception from predators, other group members may decrease personal efforts of vigilance (McGowan & Woolfenden, 1989;Hailman et al, 1994).…”

Section: Introductionmentioning

confidence: 99%

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Sentinels in Saltator atricollis (Passeriformes: Emberizidae)

Ragusa-Netto

2001

Rev. Bras. Biol.

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Rev. Brasil. Biol., 61(2) (With 4 figures) ABSTRACTI studied the existence of sentinels in Saltator atricollis in a 'campo-cerrado' (Brazilian savanna) during the breeding seasons of 1994-95 and 1995-96. Groups of this species consisted of two to seven birds (N = 25). Sentinels were present (mean ± sd) 62% ± 9% of the time, and most sentinel bouts lasted from less than one to six minutes (although in some occasions for more than 30 min.). Overlap of two or more sentinels occurred on average only 3.2% of the time with birds on guard. Sentinels commonly gave contact calls in the beginning and/or at the end of a sentinel bout. The group size had no effect on time with sentinels. However the encounter rate between raptors and groups significantly influenced the time guarded. The results of this study suggests that the ability of sentinels to detect predators may play a central role as an anti-predator device.Key words: Emberizidae, Brazilian savanna, raptors, alertness, sentinels. RESUMO Sentinelas em Saltator atricollis (Passeriformes: Emberizidae)Estudei a existência de sentinelas em S. atricollis em campo-cerrado, nas estações reprodutivas de 1994-95 e 1995-96. Os grupos de S. atricollis continham de dois a sete indivíduos (N = 25). Os sentinelas vigiaram os grupos (média ± dp) por 62% ± 9% do tempo, sendo que a maioria dos turnos de vigilância durou de menos de um a seis minutos (em alguns casos se extenderam por mais de 30 min.). Dois ou mais sentinelas vigiaram simultaneamente, em média, apenas 3,2% do tempo vigiado. Os sentinelas comumente emitiam chamados de contato quando iniciavam e/ou terminavam um turno de vigilância. O tamanho dos grupos não apresentou relação com o tempo vigiado. Por outro lado, a taxa de encontros entre predadores aéreos e grupos influenciou significativamente o tempo vigiado. A habilidade dos sentinelas em perceber predadores provavelmente apresenta uma função relevante, conferindo vantagens antipredatórias aos grupos dessa espécie.Palavras-chave: Emberizidae, campo-cerrado, predadores aéreos, vigilância, sentinelas.

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“…For instance, the Florida Scrub Jay is monogamous (Woolfenden and Fitzpatrick, 1984) and male helpers have lower plasma levels of testosterone than male breeders but equal levels of corticosterone, this suggests that male helpers are not reproductively suppressed as a result of aggression from the part of male breeders (Schoech et al, 1991); there is also a division of labour among the members of the group (mainly males) (e.g. sentinel system, McGowan and Woolfenden (1989)). On the other hand, the Splendid Fairy-wren is promiscuous (Brooker et al, 1990) with plural breeding also occurring inside the territory (Rowley et al, 1989) but the group members (mainly males) show some degree of division of labour during provisioning of nestlings (Rowley, 1981).…”

Section: A Modelmentioning

confidence: 99%

Inter‐generational competition and selection for helping behaviour

Poiani¹

1994

J of Evolutionary Biology

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A model is presented which considers the effects of inter-generational competition (IC) for breeding status on selection for helping behaviour. The model shows that for species with both high inter-generational overlap and high frequency of breeding opportunities within the individual's lifespan, helping behaviour is selected if the relatives raised by the helper through helping (i.e. present indirect fitness gains) do not decrease the helper's future direct fitness as a breeder. This effect is dependent on the value of a, the coefficient of IC. The occurrence of high a values can explain those cases in which a non-breeding member of a social group does not help. The effect of IX can be reduced by means of establishing an age-based queueing system to attain breeding status. The breeders' acceptance of a non-helping individual within their territory may be explained as extended parental care or parental facilitation.

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A sentinel system in the Florida scrub jay

Cited by 158 publications

References 25 publications

Vigilance by Sentinels in a Group of Baboons (Papio hamadryas hamadryas) in a Zoo Setting

Vigilance by Sentinels in a Group of Baboons (Papio hamadryas hamadryas) in a Zoo Setting

Sentinels in Saltator atricollis (Passeriformes: Emberizidae)

Inter‐generational competition and selection for helping behaviour

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