How should breeders react when aided by helpers?

Carranza, Juan; Polo, Vicente; Valencia, Juliana; Martín, Concha Mateos; Solis, Carlos

doi:10.1016/j.anbehav.2007.10.006

Cited by 25 publications

(37 citation statements)

References 19 publications

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“…In particular, we were interested to see whether mothers compensated their investment per egg when counting on helpers (Russell et al ) or, alternatively, if they would follow the same patterns as at the nestling stage (Valencia et al ), hence increasing investment when helpers are available to predictably contribute to raising the brood. We base this latter hypothesis on previous evidence that the presence of helpers reduces predation risk (Valencia et al ) and hence increases the reproductive value of the clutch/brood (Carranza et al ). A higher reproductive value of offspring may promote an increase in optimal maternal allocation in that season compared to other seasons throughout the mothers's reproductive lifetime.…”

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Maternal allocation in eggs when counting on helpers in a cooperatively breeding bird

Valencia

Martín

Solis

et al. 2017

Journal of Avian Biology

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For cooperatively breeding birds, it has been proposed that breeders should reduce their investment in eggs when they count on helpers, because this can be compensated for by helpers provisioning of nestlings. Data from some species have supported this prediction, but this is not the case in others. It has also been proposed that mothers should not reduce but rather increase investment if the presence of helpers enhances the reproductive value of offspring, a pattern that might also influence egg production as long as helpers are predictable for laying females. Here, we studied maternal expenditure in eggs and clutches in the Iberian magpie, to see whether mothers reduce their expenditure at the egg stage in the presence of helpers. Our results show that investment in clutches varied depending on the year, date in the season and age of the mother, but there were no reductions in maternal expenditure per individual egg when they counted on helpers. On the contrary, a pattern emerged in the opposite direction of more investment in eggs associated with the future presence of helpers at the nestling stage. Our data suggest that the predictability of helpers, along with the type of benefits accrued from the contribution of helpers, may be crucial to understanding the reaction of mothers at egg production.

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confidence: 93%

Maternal allocation in eggs when counting on helpers in a cooperatively breeding bird

Valencia

Martín

Solis

et al. 2017

Journal of Avian Biology

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“…In cooperatively breeding birds, breeders may be assisted by helpers in caring for offspring (Brown 1987;Koenig and Dickinson 2004) and adjust their parental care effort without affecting nestling survival probability. As a consequence, the parents may have more time and energy to invest in other activities, such as feeding, mating or territory defense.…”

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confidence: 99%

Helpers at the nest of White-banded Tanager Neothraupis fasciata benefit male breeders but do not increase reproductive success

Manica

Marini

2011

J Ornithol

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In cooperatively breeding birds, breeders can adjust their parental care investment without affecting nestling survival probability and save energy to invest in other activities, such as feeding, mating or territory defense. Furthermore, helpers at the nest can improve nestling nutrition and hence the reproductive performance of the breeding pair. We determined the influence of helpers on nestling feeding effort and reproductive success of breeders in the neotropical White-banded Tanager (Neothraupis fasciata). We monitored nests during the breeding seasons of 2006 and 2007 in central Brazil. Males showed a compensatory reduction of their food delivery rate in the presence of helpers, whereas females exhibited the same parental effort regardless of having helpers. Total food delivery rate was higher for nests with helpers, but there was no effect of helpers on reproductive performance of breeders (clutch size, hatching rate, fledgling productivity and reproductive success). Our results indicate that cooperative breeding in the White-banded Tanager appears to be important for males to reduce their parental care effort and, hence, invest in their survival or future reproductive attempts. Zusammenfassung Bei kooperativ brütenden Vögeln können Brüter ihren Brutpflegeaufwand anpassen, ohne dass dies die Ü berlebenswahrscheinlichkeit der Nestlinge beeinträchtigt, und Energie sparen, die dann in andere Aktivitäten, wie Nahrungsaufnahme, Paarung oder Revierverteidigung, investiert werden kann. Außerdem können Helfer am Nest die Ernährung der Nestlinge und somit die Fortpflanzungsleistung des Brutpaares verbessern. Wir haben ermittelt, wie sich Helfer auf den NestlingsFütterungsaufwand und den Fortpflanzungserfolg von brü-tenden neotropischen Flügelbindentangaren (Neothraupis fasciata) auswirken. Wir haben Nester während der Brutsaisons 2006 und 2007 in Zentralbrasilien überwacht. Männchen zeigten eine kompensatorische Reduktion ihrer Fütterungsrate in Anwesenheit von Helfern, während Weibchen denselben Elternaufwand zeigten, unabhängig davon, ob sie Helfer hatten oder nicht. Die Gesamtfütterungsrate war für Nester mit Helfern höher, doch Helfer hatten keinen Einfluss auf die Fortpflanzungsleistung von Brütern (Gelegegröße, Schlupfrate, Flügglingsproduktion und Fortpflanzungserfolg). Unsere Ergebnisse deuten darauf hin, dass kooperatives Brüten bei Flügelbindentangaren für Männchen wichtig zu sein scheint, um ihren Brutpflegeaufwand zu reduzieren und folglich in ihr Ü berleben oder weitere Fortpflanzungsversuche zu investieren.

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“…Therefore, dominant pairs may benefit from lightened workload, higher survivorship, and future reproductive prospects (Sydeman , Khan and Walters ), but not enhanced nest productivity. However, if they maintain constant or even increase feeding rates (Valencia et al , Carranza et al ), dominant pairs may benefit from enhanced fecundity but not survivorship and future reproductive prospects, because both the number and body mass of fledglings may increase (Hatchwell et al , Woxvold and Magrath ). Then, a question arises – which conditions determine the types of assistance helpers provide and, consequently, the response of dominant pairs?…”

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Helper effects in the azure‐winged magpie Cyanopica cyana in relation to highly‐clumped nesting pattern and high frequency of conspecific nest‐raiding

Ren

Luo

et al. 2016

Journal of Avian Biology

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In avian cooperative breeding systems, many benefi ts obtained by social pairs from the presence of helpers have been uncovered. However, until now, the factors that determine the type of assistance helpers provide and the responses of social pairs have not been well illustrated. We examined the contribution of helpers to cooperative groups and the relevant responses of dominant pairs in the azure-winged magpie Cyanapica cyana which breeds on the Tibetan Plateau. We used the capture -mark -recapture method to identify helpers. Results showed that helpers were mostly the yearling sons of dominant pairs. Th ey mainly contributed to the cooperative group in three ways, courtship-feeding the incubation female, provisioning the brood, and defending the nest. For responses of dominant pairs, we unexpectedly found that clutch size was not infl uenced by the presence of helpers at the nest. However, cooperative groups had higher brood feeding rates than biparental nests and their feeding pattern also diff ered to that of the latter. Consequently, nestlings in cooperative groups had larger fl edging body mass than that in biparental nests. By examining reasons for nest failure, we revealed that conspecifi c nest-raiding contributed to more nest failure than any other natural predators. Because of the contribution of helpers in defending against both predators and conspecifi c nest-raiders, cooperative groups had higher survival rate than biparental nests. Th us, our fi ndings suggest that in a highly-clumped nesting pattern, factors concerning the risk of nest predation, rather than that infl uencing food supply, play an important role in determining helper eff ects and responses of aided dominant pairs.

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How should breeders react when aided by helpers?

Cited by 25 publications

References 19 publications

Maternal allocation in eggs when counting on helpers in a cooperatively breeding bird

Maternal allocation in eggs when counting on helpers in a cooperatively breeding bird

Helpers at the nest of White-banded Tanager Neothraupis fasciata benefit male breeders but do not increase reproductive success

Helper effects in the azure‐winged magpie Cyanopica cyana in relation to highly‐clumped nesting pattern and high frequency of conspecific nest‐raiding

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