Older female little penguins Eudyptula minor adjust nutrient allocations to both eggs

Ramírez, Francisco; Forero, Manuela G.; Hobson, Keith A.; Chiaradia, André

doi:10.1016/j.jembe.2015.03.020

Cited by 15 publications

(25 citation statements)

References 35 publications

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“…Although it is difficult to discern which variables had more relative importance (Table 3) in the 27% explained deviance of this full model, it highlights how body mass varies among all covariates. Males were always heavier than females (Figure 4), except at pre-laying when there was no difference between sexes (Figure 4), in agreement with Ramírez et al (2015) who used a much large body mass dataset.…”

Section: Body Masssupporting

confidence: 83%

Stable Isotopes (δ13C, δ15N) Combined with Conventional Dietary Approaches Reveal Plasticity in Central-Place Foraging Behavior of Little Penguins Eudyptula minor

et al. 2016

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Marine top and meso predators like seabirds are limited by the need to breed on land but forage on limited or patchily distributed resources at sea. Constraints imposed by such central-place foraging behavior change during breeding or even disappear outside the breeding period when there is no immediate pressure to return to a central place. However, central place foraging is usually factored as an unchanging condition in life history studies. Here we used little penguin Eudyptula minor, a resident bird with one of the smallest foraging range among seabirds, to examine the different degree of pressure/constraints of being a central-place forager. We combined data on isotopic composition ( 13 δ C and 15 δ N), conventional stomach contents and body mass of little penguins breeding at Phillip Island, Australia over 9 years (2003)(2004)(2005)(2006)(2007)(2008)(2009)(2010)(2011). We explored relationships between diet and body mass in each stage of the breeding season (pre-laying, incubation, guard, and post-guard) in years of "high" and "low" reproductive success. Values of 13 C and 15 δ δ N as well as isotopic niche width had similar patterns among years, with less variability later in the season when little penguins shorten their foraging range at the expected peak of their central-place foraging limitation. Body mass peaked before laying and hatching in preparation for the energetically demanding periods of egg production and chick provisioning. An increase of anchovy and barracouta in the diet, two major prey for little penguins, occurred at the critical stage of chick rearing. These intra-annual trends could be a response to imposed foraging constraints as reproduction progresses, while inter-annual trends could reflect their ability to match or mismatch the high energy demanding chick rearing period with the peak in availability of high-quality prey such as anchovy. Our findings underline the key advantages of using a stable isotope approach combined with conventional dietary reconstruction to reveal an otherwise intractable ecological issue of different constrains of being a central-place forager, such as the little penguin, which could be applied to other marine species.

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Section: Body Masssupporting

confidence: 83%

Stable Isotopes (δ13C, δ15N) Combined with Conventional Dietary Approaches Reveal Plasticity in Central-Place Foraging Behavior of Little Penguins Eudyptula minor

et al. 2016

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“…The size of individual eggs was unaffected by environmental conditions such as temperature or winter rainfall, and was higher for adult mothers compared to juveniles. Egg volume also varied greatly among individual mothers, a pattern that did not differ from that commonly found for many bird species (Saether , Christians , Ramirez et al ). Juvenile females increased egg volume when eggs were laid late in the season.…”

Section: Discussionsupporting

confidence: 53%

“…Under these conditions, the theoretical model by Carranza et al (2008) predicts that parents should not reduce their expenditure but rather increase it, as they actually do (Valencia et al 2006). many bird species (Saether 1990, Christians 2002, Ramirez et al 2015. Juvenile females increased egg volume when eggs were laid late in the season.…”

Section: Discussionmentioning

confidence: 99%

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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“…2011 a , Ramírez et al. ). We found that breeding adults alternated between short foraging trips (≤2 d) to feed their chicks and long trips (≥3 d) to restore adult body reserves (Saraux et al.…”

Section: Introductionmentioning

confidence: 99%

Negative effects of wind speed on individual foraging performance and breeding success in little penguins

Saraux

Chiaradia

Salton

et al. 2016

Ecological Monographs

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Most effects of environmental and climate variability on predator life history traits and population dynamics result from indirect effects mediated through the food chain. There is growing evidence that wind strength might affect seabirds while foraging at sea. Here, we investigated the effect of wind speed on the foraging performance of a flightless marine predator, the little penguin (Eudyptula minor). To this end, we used satellite‐derived wind data collected over 11 breeding seasons during which the daily attendance and body mass changes of more than 200 penguins breeding at Phillip Island (Victoria, Australia) were recorded by an automated penguin monitoring system. Over 17 363 foraging trips, we found that wind speed had important effects on foraging and provisioning parameters in breeding adults. During incubation and chick‐guard, stronger winds were associated with decreased foraging efficiency (lower body mass gain). During chick‐guard, stronger winds were furthermore associated with lower meal sizes provided to the chicks, but parental body reserves appeared unaffected. Under extreme wind conditions (>14 m/s) during the post‐guard phase, adults maintained their body reserves by shifting towards longer foraging trips, while providing chicks with smaller meals. Chick meal size and foraging trip duration during chick rearing had direct effects on breeding success, suggesting that the influence of wind on individual fitness was mediated by changes in foraging performances and success. Furthermore, using a long‐term wind data series spanning 150‐yr from a coastal wind station, we found a slight decline in wind speed and a decrease in wind speed variability in the Bass Strait where little penguins forage. Interestingly, based on this wind data, we found birds to be more directly affected by punctual events of strong winds (e.g. storms or gales), than by an overall change in wind patterns over time. Potential candidate mechanisms mediating the effects of wind speed on foraging efficiency may include swell formation, energy costs of travelling and thermoregulation, and a possible disruption of thermoclines, which may be important for little penguins. Plasticity in foraging strategies allowed parents to partially compensate for negative wind effects.

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Older female little penguins Eudyptula minor adjust nutrient allocations to both eggs

Cited by 15 publications

References 35 publications

Stable Isotopes (δ13C, δ15N) Combined with Conventional Dietary Approaches Reveal Plasticity in Central-Place Foraging Behavior of Little Penguins Eudyptula minor

Stable Isotopes (δ13C, δ15N) Combined with Conventional Dietary Approaches Reveal Plasticity in Central-Place Foraging Behavior of Little Penguins Eudyptula minor

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

Negative effects of wind speed on individual foraging performance and breeding success in little penguins

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