Seychelles warblers: Complexities of the helping paradox

Komdeur, Jan; Burke, Terry; Dugdale, Hannah L.; Richardson, David S.

doi:10.1017/cbo9781107338357.013

Cited by 28 publications

(53 citation statements)

References 69 publications

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“…The Seychelles warbler is a small insectivorous passerine endemic to the Seychelles archipelago in the Indian Ocean (Hammers et al., ; Komdeur, Dugdale, Burke, & Richardson, ). Data were collected on Cousin Island (29 ha, 04º20′S, 55º40′E) from 2002 to 2015.…”

Section: Methodsmentioning

confidence: 99%

Subordinate females in the cooperatively breeding Seychelles warbler obtain direct benefits by joining unrelated groups

Groenewoud

Kingma

Hammers

et al. 2018

Journal of Animal Ecology

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Abstract1. In many cooperatively breeding animals, a combination of ecological constraints and benefits of philopatry favours offspring taking a subordinate position on the natal territory instead of dispersing to breed independently. However, in many species individuals disperse to a subordinate position in a non-natal group ("subordinate between-group" dispersal), despite losing the kin-selected and nepotistic benefits of remaining in the natal group. It is unclear which social, genetic and ecological factors drive between-group dispersal.2. We aim to elucidate the adaptive significance of subordinate between-group dispersal by examining which factors promote such dispersal, whether subordinates gain improved ecological and social conditions by joining a non-natal group, and whether betweengroup dispersal results in increased lifetime reproductive success and survival.3. Using a long-term dataset on the cooperatively breeding Seychelles warbler (Acrocephalus sechellensis), we investigated how a suite of proximate factors (food availability, group composition, age and sex of focal individuals, population density) promote subordinate between-group dispersal by comparing such dispersers with subordinates that dispersed to a dominant position or became floaters. We then analysed whether subordinates that moved to a dominant or non-natal subordinate position, or became floaters, gained improved conditions relative to the natal territory and compared fitness components between the three dispersal strategies.4. We show that individuals that joined another group as non-natal subordinates were mainly female and that, similar to floating, between-group dispersal was associated with social and demographic factors that constrained dispersal to an independent breeding position. Between-group dispersal was not driven by improved ecological or social conditions in the new territory and did not result in higher survival. Instead, between-group dispersing females often became cobreeders, obtaining maternity in the new territory, and were likely to inherit the territory in the future, leading to higher lifetime reproductive success compared to females that floated. Males never reproduced as subordinates, which may be one explanation why subordinate between-group dispersal by males is rare.This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

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Section: Methodsmentioning

confidence: 99%

Subordinate females in the cooperatively breeding Seychelles warbler obtain direct benefits by joining unrelated groups

Groenewoud

Kingma

Hammers

et al. 2018

Journal of Animal Ecology

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“…) and all suitable habitat on the island is occupied (Komdeur ; Komdeur et al. ). As breeder dispersal is rare, vacancies are usually filled by subordinates from the same or other territories, or by floaters (Eikenaar et al.…”

Section: Methodsmentioning

confidence: 99%

“…Approximately half of all subordinate individuals engage in helping behavior in any given breeding season (incubation, nestling feeding, and territory defense; Komdeur 1994). Breeding vacancies, which arise following breeder mortality, are limited as Seychelles warblers live up to 18 years (average life span from fledging = 5.5 year; Komdeur 1991;Hammers et al 2015) and all suitable habitat on the island is occupied (Komdeur 1992;Komdeur et al 2016). As breeder dispersal is rare, vacancies are usually filled by subordinates from the same or other territories, or by floaters (Eikenaar et al 2009).…”

Section: Study System and Fieldworkmentioning

confidence: 99%

Delayed dispersal and the costs and benefits of different routes to independent breeding in a cooperatively breeding bird

et al. 2016

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Why sexually mature individuals stay in groups as nonreproductive subordinates is central to the evolution of sociality and cooperative breeding. To understand such delayed dispersal, its costs and benefits need to be compared with those of permanently leaving to float through the population. However, comprehensive comparisons, especially regarding differences in future breeding opportunities, are rare. Moreover, extraterritorial prospecting by philopatric individuals has generally been ignored, even though the factors underlying this route to independent breeding may differ from those of strict philopatry or floating. We use a comprehensive predictive framework to explore how various costs, benefits and intrinsic, environmental and social factors explain philopatry, prospecting, and floating in Seychelles warblers (Acrocephalus sechellensis). Not only floaters more likely obtained an independent breeding position before the next season than strictly philopatric individuals, but also suffered higher mortality. Prospecting yielded similar benefits to floating but lower mortality costs, suggesting that it is overall more beneficial than floating and strict philopatry. While prospecting is probably individual‐driven, although limited by resource availability, floating likely results from eviction by unrelated breeders. Such differences in proximate and ultimate factors underlying each route to independent breeding highlight the need for simultaneous consideration when studying the evolution of delayed dispersal.

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“…The sex of each individual is determined using molecular sexing methods (Griffith et al 2002). The population experiences virtually no immigration and emigration between surrounding islands (Komdeur et al 2004, 2015), and there is a 0.92±0.02 probability of annually resighting in the first 2 years of life and 0.98±0.01 probability of annually resighting in adults (Brouwer et al 2010). Subsequently, birds are presumed dead if not seen after 1 year.…”

Section: Methodsmentioning

confidence: 99%

Exploration is dependent on reproductive state, not social state, in a cooperatively breeding bird

Edwards

Dugdale

Richardson

et al. 2016

BEHECO

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Lay SummaryAn individual’s circumstances or properties—also known as state—maybe a mechanism encouraging behavioral differences among individuals. We investigated whether exploration was associated with social state or reproductive state (i.e., insect abundance at year of birth) in a wild cooperative breeder. We found fast novel object exploration was associated with young individuals born into years of high insect abundance (i.e., low future reproductive state), suggesting this behavior is reproductive state-dependent.

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Seychelles warblers: Complexities of the helping paradox

Cited by 28 publications

References 69 publications

Subordinate females in the cooperatively breeding Seychelles warbler obtain direct benefits by joining unrelated groups

Subordinate females in the cooperatively breeding Seychelles warbler obtain direct benefits by joining unrelated groups

Delayed dispersal and the costs and benefits of different routes to independent breeding in a cooperatively breeding bird

Exploration is dependent on reproductive state, not social state, in a cooperatively breeding bird

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