Changes in diet and trophic position of a top predator 10 years after a mass mortality of a key prey

Chiaradia, André; Forero, Manuela G.; Hobson, Keith A.; Cullen, J. M.

doi:10.1093/icesjms/fsq067

Cited by 69 publications

(78 citation statements)

References 60 publications

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“…Parents may thus target different locations to forage on different prey depending on whether food is to be allocated to the chicks or themselves. Stable-isotope analysis, a method used to determine diet segregation, showed that the diet of adults and chicks exhibited different d 13 C and d 15 N signatures in Little Penguins, suggesting that they do not rely on the same resources and that their foraging zones are different (Chiaradia et al 2010). Finally, long trips could also result from longer time spent foraging, but in the same areas as the ones used for short trips, as suggested by RopertCoudert et al 2004.…”

Section: Discussionmentioning

confidence: 95%

Plasticity in foraging strategies of inshore birds: how Little Penguins maintain body reserves while feeding offspring

Saraux

Robinson-Laverick

Maho

et al. 2011

Ecology

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Abstract. Breeding animals face important time and energy constraints when caring for themselves and their offspring. For long-lived species, life-history theory predicts that parents should favor survival over current reproductive attempts, thus investing more into their own maintenance than the provisioning of their young. In seabirds, provisioning strategies may additionally be influenced by the distance between breeding sites and foraging areas, and offshore and inshore species should thus exhibit different strategies. Here, we examine the provisioning strategies of an inshore seabird using a long-term data set on more than 200 Little Penguins, Eudyptula minor. They alternated between two consecutive long and several short foraging trips all along chick rearing, a strategy almost never observed for inshore animals. Short trips allowed for regular provisioning of the chicks (high feeding frequency and larger meals), whereas long trips were performed when parent body mass was low and enabled them to rebuild their reserves, suggesting that adult body condition may be a key factor in initiating long trips. Inshore seabirds do use dual strategies of alternating short and long trips, but from our data, on a simpler and less flexible way than for offshore birds.

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Section: Discussionmentioning

confidence: 95%

Plasticity in foraging strategies of inshore birds: how Little Penguins maintain body reserves while feeding offspring

Saraux

Robinson-Laverick

Maho

et al. 2011

Ecology

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“…details in Chiaradia et al, 2010Chiaradia et al, , 2014. Birds were sexed by bill measurements and weighted with spring scale to the nearest 10 g. Stomach contents were sampled by stomach flushing according to Chiaradia et al (2003Chiaradia et al ( , 2010Chiaradia et al ( , 2012.…”

Section: Study Area and Fieldwork Proceduresmentioning

confidence: 99%

“…Whole blood was freeze-dried, then powdered. Subsamples of powdered materials were weighed to the nearest µg and placed into tin capsules for Chiaradia et al, 2010). The remaining samples were analyzed at the Laboratory of Stable Isotopes of the Estación Biológica de Doñana (LIE-EBD, www.ebd.csic.es/lie/index.html) using a continuous flow isotope-ratio mass spectrometry system (Thermo Electron) consisting of a Flash HT Plus elemental analyzer interfaced with a Delta V Advantage mass spectrometer.…”

Section: Stable Isotope Analysesmentioning

confidence: 99%

“…Detailed diet results have been published elsewhere (Chiaradia et al, 2003(Chiaradia et al, , 2010(Chiaradia et al, , 2012. Four main prey were included in the statistical analysis: barracouta (Thyrsites atun), anchovy (Engraulis australis), Gould's squid (Nototodarus gouldi), and pilchard (Sardinops sagax).…”

Section: Parameters Estimation and Statistical Testingmentioning

confidence: 99%

“…Moreover, there is evidence that little penguin body mass also varies significantly in response to variations in breeding onset Salton et al, 2015) and foraging decisions (Saraux et al, 2011b). Little penguin diet can change dramatically between breeding stages (Chiaradia et al, 2003(Chiaradia et al, , 2010(Chiaradia et al, , 2012. As result, the events that drive success or failure within each breeding stage is independent of each other (Saraux et al unpublished).…”

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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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Evaluation of artificial nest sites for long-term conservation of a burrow-nesting seabird

2014

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The persistence of many cavity‐nesting animals is threatened by habitat modification and a shortage of suitable breeding sites. Consequently, provision of alternative breeding sites is a frequently applied short‐ to medium‐term conservation action. However, the effectiveness of provisioning for breeding success and persistence of breeding animals is rarely considered and could lead populations into an ecological trap. We evaluated the effectiveness of providing nest boxes for little penguins (Eudyptula minor) compared with natural nests over 25 years. We assessed nest‐box adoption and occupancy rates, compared breeding success (i.e., hatching and fledging success) and indices of productivity (i.e., observed brood size, total fledged chick mass, and the number of clutch initiations) with nest survival models and log‐linear mixed effects models, and compared long‐term residency patterns with Link–Barker mark‐recapture models between artificial and natural nests. Little penguins readily adopted nest boxes and breeding attempts were recorded in about 92% of nest boxes installed for 7 or more years. Breeding productivity from 6,081 monitored clutches varied by year and was similar across nest types in most years, but in poor breeding seasons nest boxes performed better. Survival rates to hatching and fledging averaged 7.6% and 8.6% greater in nest boxes, respectively. Similarly, the average total observed mass of chicks produced per clutch was 11% heavier in nest boxes. Annual site fidelity of 2,331 breeding penguins was similar in areas with nest boxes and areas with natural burrows, despite an average of 35% of natural burrows collapsing each year. Nest‐box provisioning for little penguins overcomes local nest‐site limitation, improves breeding success, and can result in local population increases, so is not indicative of an ecological trap. However, a self‐sustaining local population in the long term will require management strategies that address the underlying processes inhibiting population recovery and assist the transition from artificial nest sites back to natural nest sites. © 2014 The Wildlife Society.

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Changes in diet and trophic position of a top predator 10 years after a mass mortality of a key prey

Cited by 69 publications

References 60 publications

Plasticity in foraging strategies of inshore birds: how Little Penguins maintain body reserves while feeding offspring

Plasticity in foraging strategies of inshore birds: how Little Penguins maintain body reserves while feeding offspring

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

Evaluation of artificial nest sites for long-term conservation of a burrow-nesting seabird

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