Loyalty pays: potential life history consequences of fidelity to marine foraging regions by southern elephant seals

Bradshaw, Corey J. A.; Hindell, Mark A.; Sumner, Michael; Michael, Kelvin

doi:10.1016/j.anbehav.2003.12.013

Cited by 189 publications

(215 citation statements)

References 58 publications

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“…Our analysis may suggest an important role for maternal foraging strategies in shaping population trends on îles Kerguelen [51]. Some evidence suggests that southern elephant seal females are faithful to their foraging grounds [43]. The relatively stable mixture proportions across years observed in this study could reflect a stable commitment of females to a foraging strategy.…”

Section: Discussionmentioning

confidence: 68%

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O' mother where wert thou? Maternal strategies in the southern elephant seal: a stable isotope investigation

et al. 2012

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Maternal effects are widespread in ecology and can alter the dynamics of a population. We investigated the impact of maternal foraging strategies on offspring weaning mass-a proxy of maternal foraging success and of offspring survival-in southern elephant seals on îles Kerguelen. Using 4 years of data, we modelled pup weaning mass as a two-component mixture and used blood stable isotope values to discriminate between maternal foraging strategies previously identified from bio-logging studies. Carbon isotope ratio was a strong predictor of weaning mass, but the relationship was non-monotonic in contrast to a priori expectations. Females foraging in the interfrontal zone weaned pups with a smaller mass compared with females foraging in Antarctic waters. Pup mass was positively correlated with a proxy of global primary production in the interfrontal zone for small weanlings. Maternal effects, via a poor foraging efficiency in the 1970s, may help explain the large population decrease observed at that time on îles Kerguelen because of an overall decrease in pup weaning mass, survival and subsequent recruitment.

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Section: Discussionmentioning

confidence: 68%

“…This relationship was expected as older females are more experienced and, also being larger, can store more energy to transfer to their pup. For this interpretation to hold, we assumed that breeding females had a stable foraging strategy [43,44] and that younger females used the interfrontal zone as much as older females.…”

Section: Results (A) Stable Isotopesmentioning

confidence: 99%

O' mother where wert thou? Maternal strategies in the southern elephant seal: a stable isotope investigation

et al. 2012

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“…It is typical for predators hunting at spatial scales exceeding their sensory range [7][8][9][10]. For instance, blind search is observed for plankton-feeding basking sharks [11], jellyfish predators and leatherback turtles [12], and southern elephant seals [13]. Saltatory search is distinguished from cruise search, when the searcher continues to explore its environment during relocations.…”

Section: Introductionmentioning

confidence: 99%

Space-fractional Fokker–Planck equation and optimization of random search processes in the presence of an external bias

2014

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We study the efficiency of random search processes based on Lévy flights with power-law distributed jump lengths in the presence of an external drift, for instance, an underwater current, an airflow, or simply the bias of the searcher based on prior experience. While Lévy flights turn out to be efficient search processes when relative to the starting point the target is upstream, in the downstream scenario regular Brownian motion turns out to be advantageous. This is caused by the occurrence of leapovers of Lévy flights, due to which Lévy flights typically overshoot a point or small interval. Extending our recent work on biased LF search [V. V. Palyulin, A. V. Chechkin, and R. Metzler, Proc. Natl. Acad. Sci. USA, 111, 2931 (2014).] we establish criteria when the combination of the external stream and the initial distance between the starting point and the target favors Lévy flights over regular Brownian search. Contrary to the common belief that Lévy flights with a Lévy index α = 1 (i.e., Cauchy flights) are optimal for sparse targets, we find that the optimal value for α may range in the entire interval (1, 2) and include Brownian motion as the overall most efficient search strategy.

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“…In the field of movement ecology (6), such random jump-like search processes are often referred to as "blind search" using saltatory motion, which is typical for predators hunting at spatial scales that exceed their sensory range (7)(8)(9)(10). Such blind search, inter alia, was observed for fully aquatic marine vertebrate predators including plankton-feeding basking sharks (Cetorhinus maximus) (11), jellyfish predators, leatherback turtles (Dermochelys coriacea) (12), and southern elephant seals (13). This is the kind of search motion we investigate here.…”

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confidence: 99%

Lévy flights do not always optimize random blind search for sparse targets

Palyulin

Chechkin

Metzler

2014

Proc. Natl. Acad. Sci. U.S.A.

191

213

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It is generally believed that random search processes based on scalefree, Lévy stable jump length distributions (Lévy flights) optimize the search for sparse targets. Here we show that this popular search advantage is less universal than commonly assumed. We study the efficiency of a minimalist search model based on Lévy flights in the absence and presence of an external drift (underwater current, atmospheric wind, a preference of the walker owing to prior experience, or a general bias in an abstract search space) based on two different optimization criteria with respect to minimal search time and search reliability (cumulative arrival probability). Although Lévy flights turn out to be efficient search processes when the target is far from the starting point, or when relative to the starting point the target is upstream, we show that for close targets and for downstream target positioning regular Brownian motion turns out to be the advantageous search strategy. Contrary to claims that Lévy flights with a critical exponent α = 1 are optimal for the search of sparse targets in different settings, based on our optimization parameters the optimal α may range in the entire interval (1, 2) and especially include Brownian motion as the overall most efficient search strategy.search optimization | stochastic processes | Lévy foraging hypothesis H ow do you find the proverbial needle in the haystack or an enemy submarine in the vast expanse of the sea? Scientists have studied the dynamics and optimization of search processes for decades, their interests ranging from military tasks such as locating enemy vessels or mines in the ocean and search strategies of animals for food to diffusion control of molecular processes in biological cells (1-4). Without prior knowledge about the location of the target, a searcher randomly explores the search space. However, as already argued by Shlesinger and Klafter (5), instead of performing a Brownian walk a better search strategy for sparse targets is that of a Lévy flight (LF): The agent moves randomly with a power-law distribution λðxÞ ' jxj −1−α of relocation lengths. Owing to their scale-free, fractal character, LFs combine local exploration with decorrelating, long-range excursions. These effect a reduced oversampling compared with Brownian search (i.e., the forager is less likely to return to previously visited sites). In the field of movement ecology (6), such random jump-like search processes are often referred to as "blind search" using saltatory motion, which is typical for predators hunting at spatial scales that exceed their sensory range (7-10). Such blind search, inter alia, was observed for fully aquatic marine vertebrate predators including plankton-feeding basking sharks (Cetorhinus maximus) (11), jellyfish predators, leatherback turtles (Dermochelys coriacea) (12), and southern elephant seals (13). This is the kind of search motion we investigate here.How commonly are LFs actually observed in nature? Apart from the flight of the albatross (14, 15), power-law relocation...

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Loyalty pays: potential life history consequences of fidelity to marine foraging regions by southern elephant seals

Cited by 189 publications

References 58 publications

O' mother where wert thou? Maternal strategies in the southern elephant seal: a stable isotope investigation

O' mother where wert thou? Maternal strategies in the southern elephant seal: a stable isotope investigation

Space-fractional Fokker–Planck equation and optimization of random search processes in the presence of an external bias

Lévy flights do not always optimize random blind search for sparse targets

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