Intra- and interannual variation in the diet of the Magellanic penguin (Spheniscus magellanicus) at Martillo Island, Beagle Channel

Scioscia, Gabriela; Rey, Andrea Raya; Samaniego, Ricardo Andres Saenz; Florentín, Olga; Schiavini, Adrián

doi:10.1007/s00300-014-1532-8

Cited by 49 publications

(46 citation statements)

References 48 publications

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“…Additionally, many studies often lack independent, quantitative estimates of prey abundance (e.g., Scioscia et al, 2014;Webb and Harvey, 2014). Some studies, however, have shown similar narrowing of dietary niches under changing availability of key prey species.…”

Section: Discussionmentioning

confidence: 99%

Dietary Niche Shifts of Multiple Marine Predators under Varying Prey Availability on the Northeast Newfoundland Coast

et al. 2017

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Understanding species interactions among top marine predators and interactions with their prey can provide important insight into community-level responses to changing prey availability and the role of apex predators as indicators of ecosystem change. On the northeast Newfoundland coast, marine predators rely on capelin (Mallotus villosus), a dominant forage fish, as a food source. Capelin migrate into coastal regions to spawn during July, essentially transforming the food supply from low during early summer (i.e., pre-spawning) to high later in the summer (i.e., spawning). During July-August, 2016, we used stable isotopic ratios of nitrogen (δ 15 N) and carbon (δ 13 C) to investigate shifts in dietary niche metrics at the predator group-level (trophic position, dietary niche breadth) and community-level (niche overlap, trophic diversity) for multiple marine predators under varying capelin availability. Predator groups included non-breeding shearwaters (great shearwater Ardenna gravis, sooty shearwater A. grisea), humpback whales (Megaptera novaeangliae), and gull chicks (herring gull Larus argentatus, great black-backed gull Larus marinus). We also tested the sensitivity of community-level dietary metrics to a variety of published trophic discrimination factors. Tissue samples from shearwaters (blood cellular component), gull chicks (whole blood), and whales (skin), representing average diets over 2-3 weeks, were collected during three periods (early, mid, late) corresponding to increasing capelin availability. Isotopic niche breadth (Standard Ellipse Area, SEA b ) narrowed and trophic position shifted toward higher δ 15 N for all predator groups as capelin availability increased, suggesting a higher reliance on capelin. Trophic diversity (distance to centroid) decreased with increased capelin availability, while pairwise niche overlap between predator groups was highly variable and sensitive to trophic discrimination factors. Findings suggest that although capelin is the dominant forage fish during the summer, predators rely on capelin as prey to varying degrees. Combining species-and community-level metrics of dietary niche and trophic diversity may provide a more complete picture of predator responses to prey availability and, thus, may be important monitoring tools to indicate changes in the food supply of marine predators.

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Section: Discussionmentioning

confidence: 99%

Dietary Niche Shifts of Multiple Marine Predators under Varying Prey Availability on the Northeast Newfoundland Coast

et al. 2017

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“…Shoals of Fuegian Sprat Sprattus fueguensis , an important prey for southern Magellanic Penguin colonies (Radl & Culik , Scioscia et al . ), exhibit a diel cycle, in which they disperse in superficial layers during night‐time (5–10 m) and descend (maximum 70 m), whereas during the day they form compact shoals (Sánchez et al . , Casarsa ).…”

Section: Discussionmentioning

confidence: 99%

“…, Scioscia et al . ) by Magellanic Penguins along their distribution, which reflects the availability of prey resources across their distribution range.…”

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confidence: 99%

Foraging behaviour of Magellanic Penguins during the early chick‐rearing period at Isla de los Estados, Argentina

Rosciano

Pütz²,

Polito

et al. 2017

Ibis

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Studies of the at‐sea distribution and trophic ecology of penguins are essential to understand their role in the broader marine food web. Magellanic Penguins Spheniscus magellanicus have a wide distribution and their foraging behaviour varies across breeding sites and between sexes, among others. In this study, we characterized the at‐sea areas, the diving strategies and the relative trophic level of Magellanic Penguins breeding at Isla de los Estados, Argentina, during the early chick‐rearing period. In addition, we quantified the interannual, sexual and individual variability in those parameters during three breeding seasons (2011–2013) using devices recording position and dive depth, and obtained blood samples for stable isotope analysis. During the early chick‐rearing period, Magellanic Penguins showed small differences between the sexes in their foraging behaviour and large overlap in the at‐sea areas used, suggesting no intraspecific variation between sexes. Although there was interannual variability in the foraging behaviour and the trophic level of the penguins, most of the studied nests managed successfully to raise both chicks during the first stage of the breeding cycle (guard stage). The foraging ecology of Magellanic Penguins from this colony was comparable with results of past studies at other breeding colonies. This study contributes to the identification of important at‐sea areas for Magellanic Penguins at the southern edge of their distribution and also to the identification of possible threats in the study area such as interaction with fisheries.

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“…A similar approach was taken in estimating the trophic level of Magellanic penguins breeding at Isla Martillo. At this location Magellanic penguins fed mainly on fuegian sprat (TL = 4.1, Sprattus fuegensis), representing 55% of the biomass consumed by birds (Scioscia et al, 2014). The next most important prey item was squat lobster 27 % (TL = 2.7, Munida gregaria) followed by Patagonian squid 14% (TL = 3.8, Loligo gahi) and 4% other prey (Scioscia et al, 2014).…”

Section: Trophic Level Calculationsmentioning

confidence: 98%

“…At this location Magellanic penguins fed mainly on fuegian sprat (TL = 4.1, Sprattus fuegensis), representing 55% of the biomass consumed by birds (Scioscia et al, 2014). The next most important prey item was squat lobster 27 % (TL = 2.7, Munida gregaria) followed by Patagonian squid 14% (TL = 3.8, Loligo gahi) and 4% other prey (Scioscia et al, 2014). The proportion of each prey type in the diet along with the trophic level of common prey species were incorporated into formula (3), above, to estimate trophic level of King and Magellanic penguins (IM).…”

Section: Trophic Level Calculationsmentioning

confidence: 99%

A comprehensive assessment of mercury exposure in penguin populations throughout the Southern Hemisphere: Using trophic calculations to identify sources of population-level variation

Brasso

Chiaradia

Polito

et al. 2015

Marine Pollution Bulletin

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Intra- and interannual variation in the diet of the Magellanic penguin (Spheniscus magellanicus) at Martillo Island, Beagle Channel

Cited by 49 publications

References 48 publications

Dietary Niche Shifts of Multiple Marine Predators under Varying Prey Availability on the Northeast Newfoundland Coast

Dietary Niche Shifts of Multiple Marine Predators under Varying Prey Availability on the Northeast Newfoundland Coast

Foraging behaviour of Magellanic Penguins during the early chick‐rearing period at Isla de los Estados, Argentina

A comprehensive assessment of mercury exposure in penguin populations throughout the Southern Hemisphere: Using trophic calculations to identify sources of population-level variation

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