Consequences of sibling rivalry vary across life in a passerine bird

Abstract

Lay SummaryOffspring raised with siblings often have to compete for access to limited parental resources; but in adulthood, this prior exposure to competition may be beneficial rather than costly. In Seychelles warblers, nestlings raised with competitors suffered more than those raised alone; but during adulthood, those raised with competition appeared to outperform those raised singly. These results suggest a more multifaceted link between early-life competition and lifetime performance than is currently assumed.

Joint effects of brood size and resource availability on sibling competition

“…annelids: Burd, Govedich & Bateson, 2006;insects: Kölliker 2007;Smiseth, Lennox & Moore, 2007; birds: Byholm, Ruosi & Sole, 2011;Bebbington, Kingma, Fairfield, Spurgin, Komdeur & Richardson, 2017;mammals: Hofer & East 2008;Andersen, Naevdal & 45 Bøe, 2011), often occurring through sublethal scramble competition (begging) or lethal aggressive brood reduction (siblicide) (Mock & Parker, 1997;Roulin & Dreiss, 2012). The key ecological factor favouring sibling competition is limitation of resources critical for offspring development, such as food (Mock & Parker, 1997;Roulin & Dreiss, 2012).…”

Helpers compensate for age-related declines in parental care and offspring survival in a cooperatively breeding bird

“…To establish whether a subordinate provided nest care (helper) or not (non-helping subordinate) we conducted nest watches of at least 60 minutes (max. 90 minutes) during both the incubation and nestling provisioning stages (21,39). We used the nest watches performed during the nestling provisioning stage to assess provisioning rates.…”

“…We used the nest watches performed during the nestling provisioning stage to assess provisioning rates. Previous work on Seychelles warblers has shown that a single 60-minute nest watch provides a representative measure of provisioning rate at the focal nest throughout the provisioning stage (39).We recorded the number of provisioning events (i.e. each food delivery to the nestling) by each provisioning individual in the territory (i.e.…”

Compensatory and additive helper effects in the cooperatively breeding Seychelles warbler (Acrocephalus sechellensis)

“…This model was the same as the provisioning model except that the response was the total number of feeds, the parameters describing sex and bird identity were omitted and the model ran for 2.1×10 7 iterations with a 1×10 6 burn-in and 2×10 3 thinning. Provisioning observations of nests with more than one nestling can be confounded by factors such as sibling competition (Bebbington et al 2017) and reduced statistical power resulting from low sample size of nests with more than one nestling (48/523). We therefore ran additional models with identical settings, excluding number of offspring as a fixed effect.…”