From ecologically equivalent individuals to contrasting colonies: quantifying isotopic niche and individual foraging specialization in an endangered oceanic seabird

Wiley, Anne E.; Rossman, Sam; Ostrom, Peggy H.; Penniman, Jay F.; Bailey, Cathleen N.; Duvall, Fern; Zipkin, Elise F.; James, Helen F.

doi:10.1007/s00227-019-3483-7

Cited by 14 publications

(7 citation statements)

References 53 publications

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“…We preliminarily tested the null hypothesis of no individual specialization, that is, that the eight populations were actually made up by generalists with resource use probabilities equal to those of the whole population (as in, e.g., colonial seabirds: Wiley et al 2019). Subsequently, we verified whether populations with a greater degree of individual specialization exhibited wider trophic niches in agreement with the NVH.…”

Section: Introductionmentioning

confidence: 99%

Interspecific and interpopulation variation in individual diet specialization: Do environmental factors have a role?

Lunghi

Manenti

Cianferoni

et al. 2020

Ecology

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Individual diet specialization (IS) has important community-and populationlevel implications and its ecological drivers are actively investigated. Here, to test the hypothesis that local environmental conditions may influence IS in wild populations, we analyzed the stomach contents of 395 individuals from eight populations of five allopatric species of European cave salamanders (genus Hydromantes). We assessed whether their degree of individual diet specialization (1) scaled positively with the respective niche widths, in agreement with Van Valen's niche variation hypothesis (NVH), and (2) could be predicted by satellite-derived climatic and vegetation characteristics of the sites where the populations live. Consistent with the NVH, the degree of individual diet specialization increased with the populations' total niche width. Furthermore, two variables describing local nonarboreal vegetation cover and habitat heterogeneity successfully predicted the variation in individual specialization across the eight populations. Climatic factors had a generally low predictive power, with individual specialization in low-and high-elevation populations showing contrasting patterns of co-variation with air temperature in the warmest quarter of the year. However, independently from elevation, specialization peaked under conditions of high nonarboreal vegetation cover and high precipitation regimes. We discussed the results against two mutually nonexclusive scenarios hypothesizing different mechanisms linking environmental factors to salamanders' trophic strategy at an individual and population level. We concluded that satellite-derived climatic and vegetation variables to date generally adopted to model Grinnellian niches might also be useful in predicting spatial variations in dietary habits of populations, that is, their Eltonian niches.

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Section: Introductionmentioning

confidence: 99%

Interspecific and interpopulation variation in individual diet specialization: Do environmental factors have a role?

Lunghi

Manenti

Cianferoni

et al. 2020

Ecology

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“…In addition, it is likely that we observed greater population-level aggregation in razorbills partly due to their more specialised feeding habits than guillemots. Studies of diet specialisation, such as through stable isotope analyses of feathers (Wiley et al 2019, Barrionuevo et al 2020, may therefore be useful in predicting levels of non-breeding population aggregation and therefore vulnerability to marine threats in other seabird species or unstudied populations of our study species, which could be of great use to seabird conservation as it may highlight situations where multi-colony tracking studies are required.…”

Section: Discussionmentioning

confidence: 99%

Interspecific variation in non-breeding aggregation: a multi-colony tracking study of two sympatric seabirds

Buckingham¹,

Bogdanova²,

Green³

et al. 2022

Mar. Ecol. Prog. Ser.

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Migration is a widespread strategy for escaping unfavourable conditions during winter, but the extent to which populations that segregate during the breeding season aggregate during the non-breeding season is poorly understood. Low non-breeding season aggregation may be associated with higher likelihood of overlap with threats, but with fewer populations affected, whereas high aggregation may result in a lower probability of exposure to threats, but higher overall severity. We investigated non-breeding distributions and extent of population aggregation in 2 sympatrically breeding auks. We deployed geolocation-immersion loggers on common guillemots Uria aalge and razorbills Alca torda at 11 colonies around the northern UK and tracked their movements across 2 non-breeding seasons (2017-18 and 2018-19). Using 290 guillemot and 135 razorbill tracks, we mapped population distributions of each species and compared population aggregation during key periods of the non-breeding season (post-breeding moult and mid-winter), observing clear interspecific differences. Razorbills were largely distributed in the North Sea, whereas guillemot distributions were spread throughout Scottish coastal waters and the North, Norwegian and Barents Seas. We found high levels of aggregation in razorbills and a strong tendency for colony-specific distributions in guillemots. Therefore, razorbills are predicted to have a lower likelihood of exposure to marine threats, but more severe potential impact due to the larger number of colonies affected. This interspecific difference may result in divergent population trajectories, despite the species sharing protection at their breeding sites. We highlight the importance of taking whole-year distributions into account in spatial planning to adequately protect migratory species.

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“…2011, Wiley et al. 2019), because they can be applied to quantify individual‐ and population‐level parameters of variability along resource axes. For example, δ 13 C may be used to investigate IS of habitat use/primary production sources, whereas δ 15 N may reflect IS in dietary preference (e.g., exploiting prey of different trophic/functional roles).…”

Section: Individual Specializationmentioning

confidence: 99%

“…Ultimately, these patterns indicate how individual realized niche widths compare to the realized niche of the population, which are often compared across populations and/or species and contexts (e.g., food web structure, environmental conditions, human disturbance). Bulk stable isotope ratios have become widely used to describe patterns of dietary IS in many terrestrial (e.g., Ara ujo et al 2009, Maldonado et al 2017, freshwater (e.g., Harrison et al 2017), and marine taxa (e.g., Matich et al 2011, Wiley et al 2019, because they can be applied to quantify individual-and population-level parameters of variability along resource axes. For example, d 13 C may be used to investigate IS of habitat use/primary production sources, whereas d 15 N may reflect IS in dietary preference (e.g., exploiting prey of different trophic/functional roles).…”

Section: Individual Specializationmentioning

confidence: 99%

Are stable isotope ratios suitable for describing niche partitioning and individual specialization?

Matich

Bizzarro

Shipley

2021

Ecological Applications

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As concerns about anthropogenic and natural disturbance grow, understanding animal resource use patterns has been increasingly prioritized to predict how changes in environmental conditions, food web structure, and population dynamics will affect biological resilience. Among the tools used to assess resource use, stable isotope analysis has proliferated in ecological studies, particularly in relation to describing intra‐ and interspecific variation in trophic interactions. Despite a growing need to disseminate scientific information, the inherent limitations of stable isotope ratios and inappropriate synonymizing of distinct evolutionary and ecological processes may mislead ecological inferences in natural systems. This situation necessitates a re‐evaluation of the utility of stable isotope ratios to address certain ecological questions. Here, we assess the efficacy of stable isotope ratios to describe two fundamental ecological processes, niche partitioning and individual specialization. Investigation of these processes has increased substantially in accordance with increased access to stable isotope data. This article discusses the circumstances and approaches that are necessary to evaluate niche partitioning and individual specialization, and outlines key considerations for the associated application of stable isotope ratios.

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From ecologically equivalent individuals to contrasting colonies: quantifying isotopic niche and individual foraging specialization in an endangered oceanic seabird

Cited by 14 publications

References 53 publications

Interspecific and interpopulation variation in individual diet specialization: Do environmental factors have a role?

Interspecific and interpopulation variation in individual diet specialization: Do environmental factors have a role?

Interspecific variation in non-breeding aggregation: a multi-colony tracking study of two sympatric seabirds

Are stable isotope ratios suitable for describing niche partitioning and individual specialization?

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