Seasonal Tradeoffs in Reproductive Investment in a Multi-Brooded Passerine

Robinson, Thomas J.; Siefferman, Lynn; Risch, Thomas S.

doi:10.1525/cond.2010.080038

Cited by 15 publications

(15 citation statements)

References 42 publications

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“…2a, b). This finding is consistent with other studies demonstrating changes in parental investment across broods or nesting attempts (Biermann & Robertson, 1981; Robinson et al, 2010). In our study, WS males showed a flexible parental strategy.…”

Section: Discussionsupporting

confidence: 93%

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New insights into the hormonal and behavioural correlates of polymorphism in white-throated sparrows, Zonotrichia albicollis

2014

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The white-throated sparrow is a promising model for behavioural neuroendocrinology and genetics because behaviour and endocrine function may be linked to a chromosomal rearrangement that determines plumage colour. The notion that the two colour morphs, tan-striped (TS) and white-striped (WS), differ predictably in aggression and parenting has been widely accepted, despite conflicting evidence. It is also hypothesized that morph-typic behaviour is hormone mediated, yet no field study has measured sex steroids and behaviour in the same birds. Here, we re-evaluate the TS and WS phenotypes, describe the conditions under which they differ and investigate relationships between sex steroids and behaviour. We report that (1) during territorial intrusions, WS males were more aggressive than TS birds, but this difference was restricted to singing; WS males sang more than TS males but showed identical levels of physical aggression. WS females sang more than TS females and were also more physically aggressive. (2) TS males provisioned young more frequently than did WS males, but only during first broods. The parental strategy of WS males was flexible, and during replacement broods, WS and TS males provisioned at equal rates. (3) Consistent with previous studies, we detected no morph difference in female provisioning. (4) Plasma testosterone and dihydrotestosterone were higher in WS males than in TS males during periods of peak territorial defence and during first broods; within breeding stages, male androgen levels were positively correlated with singing and negatively correlated with provisioning. Plasma oestradiol levels were higher in WS females than in TS females and higher during peak territorial defence; oestradiol levels tended to be positively correlated with singing. Overall, our results refine the TS and WS phenotypes, show that behavioural differences between them are restricted to periods with relatively high mating opportunity, and demonstrate an association between sex steroids and morph-typic behaviour. These results will inform future studies of this promising model.

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Section: Discussionsupporting

confidence: 93%

“…In songbirds, the degree of parental investment can increase as the breeding season progresses (Biermann & Robertson, 1981; Robinson et al, 2010). In white-throated sparrows, territorial boundaries become more stable and extrapair mating opportunities decline (Falls & Kopachena, 2010).…”

Section: Reproductive Behaviourmentioning

confidence: 99%

New insights into the hormonal and behavioural correlates of polymorphism in white-throated sparrows, Zonotrichia albicollis

2014

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“…Predicted egg mass by linear volume measurements is an accurate predictor of actual egg mass (Robinson et al . ).…”

Section: Methodsmentioning

confidence: 97%

The separate effects of egg size and parental quality on the development of ornamental plumage coloration

Robinson

Siefferman

Bentz

et al. 2014

Ibis

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The fitness‐related consequences of egg size, independent of the influences of parental quality, are poorly understood in altricial birds. Not only can egg size and parental quality influence growth and survival, but each could influence the development of condition‐dependent plumage coloration in offspring. The Eastern Bluebird Sialia sialis is an altricial, multi‐brooded, cavity‐nesting passerine in which juveniles display dichromatic UV‐blue plumage. Previous research suggests that plumage coloration acts as a signal of individual quality among juvenile and adult Eastern Bluebirds. Here, we separate the effects of egg size and parental quality (defined by egg size laid) on nestling growth and plumage ornamentation by exchanging clutches of large eggs with clutches of small eggs. Nestlings were significantly larger immediately post‐hatching when hatched from a large egg, but to maintain a larger size, nestlings needed to have hatched from a large egg and to have been reared by high‐quality parents. Nestlings were brighter when reared by high‐quality parents and this relationship was strongest later in the breeding season. Nestlings exhibited greater UV chroma if hatched early in the season, but UV chroma was not significantly affected by egg size or parental quality. These findings demonstrate varying influences of both egg size and parental quality on offspring growth and plumage ornamentation but suggest that quality of post‐hatching investment is more influential than pre‐hatching investment.

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“…Alternatively, variation may be nonadaptive and simply reflect proximate factors such as weather or food availability during egg laying (Saino et al 2004, Ardia et al 2006, Whittingham et al 2007). Costs of reproduction, developmental history, and aging may also explain variation in egg size within and between females (Wheelwright and Schultz 1994, Potti 1999, Beamonte-Barrientos et al 2010, Robinson et al 2010). …”

Section: Introductionmentioning

confidence: 99%

Relative Consistency in Size, Shape, and Coloration of Savannah Sparrow Eggs within and between Breeding Seasons

2012

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Within bird populations, eggs vary extensively in size, shape, and color, but individual females tend to lay eggs that are relatively consistent in most traits. We measured all eggs laid by individual female Savannah Sparrows {Passerculus sandwichensis) breeding on Kent Island, New Brunswick, comparing subsequent clutches within the same year and in successive years. Repeatability was high for egg size and shape (0.78 and 0.72, respectively). Conversely, the repeatability of intensity of spotting was only moderate (0.46), and the background color of eggs varied from clutch to clutch and even within a clutch. Egg size increased slightly within a year from a female's first to subsequent clutch, but egg size was independent of the female's body size, the age or size of her mate, or weather conditions during clutch formation. Ranking of individual females' eggs by size and shape remained almost the same from clutch to clutch. Although laying eggs that are relatively consistent and individually distinctive in size, shape, and spotting could be an adaptation to allow fetnales to discriminate their own eggs from those of brood parasites, this explanation does not apply on Kent Island, where neither intra-nor interspecific brood parasitism occurs. We found no evidence of short-tertrt effects of egg size on the size of 7-day-old nestlings or of longterm effects on adults' survival or lifetime reproductive success. High repeatabilities suggest a substantial genetic component to variation in certain egg traits, which could limit females' ability to modify their eggs in response to environmental changes.Consistencia Relativa en Tamaño, Forma y Coloración de los Huevos de Passerculus sandwichensis dentro y entre Estaciones ReproductivasResumen. Dentro de las poblaciones de aves, los huevos varian enormemente en cuanto a tamaño, forma y color, pero las hembras individualmente tienden a poner huevos relativamente consistentes entre si para la mayoría de los rasgos. Medimos todos los huevos puestos por hembras individuales de Passercidiis sandwichensis que anidan en la Isla Kent, New Brunswick. Comparamos las nidadas subsecuentes dentro del mismo año y entre años sucesivos. El tamaño y la fortna del huevo presentó una alta repetibilidad (0.78 y 0.72, respectivamente). De modo contrario, la intensidad del manchado presentó una repetibilidad moderada (0.46) y el color de fondo de los huevos varió de una nidada a otra e incluso dentro de una nidada. El tamaño del huevo aumentó ligeramente dentro de un año desde la primera nidada de una hembra hacia las nidadas subsecuentes, pero el tamaño del huevo fue independiente del tamaño corporal de la hembra, de la edad y del tamaño de su pareja o de las condiciones meteorológicas durante la formación de la nidada. El ordenamiento de los huevos de las hembras individuales por tamaño y forma permaneció casi invariable de una nidada a otra. Aunque la puesta de huevos que son relativamente consistentes e individualmente distintivos en cuanto a tamaño, forma y manchado podria ser una adaptación ...

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Seasonal Tradeoffs in Reproductive Investment in a Multi-Brooded Passerine

Cited by 15 publications

References 42 publications

New insights into the hormonal and behavioural correlates of polymorphism in white-throated sparrows, Zonotrichia albicollis

New insights into the hormonal and behavioural correlates of polymorphism in white-throated sparrows, Zonotrichia albicollis

The separate effects of egg size and parental quality on the development of ornamental plumage coloration

Relative Consistency in Size, Shape, and Coloration of Savannah Sparrow Eggs within and between Breeding Seasons

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