ArticlePublisher preview available
To read the full-text of this research, you can request a copy directly from the authors.

Abstract and Figures

Finding food is crucial to the survival and reproductive success of individuals. Fidelity to previous proftable foraging sites may bring benefts to individuals as they can allocate more time to foraging rather than searching for prey. We studied how environmental conditions infuence when lactating long-nosed fur seals (Arctocephalus forsteri) adopt a risky (low fdelity) or conservative (high fdelity) foraging strategy at two intra-annual temporal scales when foraging in a highly variable oceanic environment. Core foraging areas (CFAs; n=534; 30×30 km cells) of consecutive foraging trips were obtained from geolocation tracks of 12 females from summer to winter in 2016 (n=5) and 2017 (n=7). We used the spatial variability (standard deviation) of CFAs between or among oceanic foraging trips as a proxy for individual foraging site fdelity (IFSF). Over the entire oceanic foraging period (n=12), IFSF in the latitudinal axis increased with stronger sea-surface temperature gradient (SSTgrad), but decreased with greater SSTgrad and sea-surface height gradient variability. Over a period of two consecutive oceanic foraging trips (n=66), IFSF decreased with greater SSTgrad variability in the earlier foraging trip. LNFS show evidence that they use IFSF as a strategy to potentially optimise food acquisition, and that this behaviour is infuenced by mesoscale oceanographic parameters.
This content is subject to copyright. Terms and conditions apply.
1 3
Marine Biology (2020) 167:76
Environmental drivers ofoceanic foraging site delity incentral place
DahliaFoo1 · MarkHindell1· CliveMcMahon2· SimonGoldsworthy3· FredBailleul3
Received: 10 September 2019 / Accepted: 27 March 2020 / Published online: 5 May 2020
© Springer-Verlag GmbH Germany, part of Springer Nature 2020
Finding food is crucial to the survival and reproductive success of individuals. Fidelity to previous profitable foraging sites
may bring benefits to individuals as they can allocate more time to foraging rather than searching for prey. We studied how
environmental conditions influence when lactating long-nosed fur seals (Arctocephalus forsteri) adopt a risky (low fidelity)
or conservative (high fidelity) foraging strategy at two intra-annual temporal scales when foraging in a highly variable oce-
anic environment. Core foraging areas (CFAs; n = 534; 30 × 30km cells) of consecutive foraging trips were obtained from
geolocation tracks of 12 females from summer to winter in 2016 (n = 5) and 2017 (n = 7). We used the spatial variability
(standard deviation) of CFAs between or among oceanic foraging trips as a proxy for individual foraging site fidelity (IFSF).
Over the entire oceanic foraging period (n = 12), IFSF in the latitudinal axis increased with stronger sea-surface temperature
gradient (SSTgrad), but decreased with greater SSTgrad and sea-surface height gradient variability. Over a period of two
consecutive oceanic foraging trips (n = 66), IFSF decreased with greater SSTgrad variability in the earlier foraging trip. LNFS
show evidence that they use IFSF as a strategy to potentially optimise food acquisition, and that this behaviour is influenced
by mesoscale oceanographic parameters.
The marine environment is highly dynamic with physical
parameters determining the spatial and temporal distribu-
tion of primary productivity, thereby resulting in patchily
distributed food resources. Marine predators, therefore, face
the challenge of locating the prey which their survival and
reproductive success depend on in this heterogeneous envi-
ronment (Oosthuizen etal. 2015). From an optimal foraging
perspective, there may be long-term breeding and survival
benefits (Bradshaw etal. 2004) for animals which use prior
knowledge about where food is (i.e., predictable) and return
to the same foraging area, rather than randomly searching
for food (Call etal. 2008). Indeed, many marine species,
such as sea birds (Weimerskirch 2007), sharks (Espinoza
etal. 2011), whales (Yates etal. 2007), turtles (Tucker etal.
2014), and seals (Oksanen etal. 2014; Arthur etal. 2015;
Abrahms etal. 2018a), display individual foraging site fidel-
ity. However, repeated use of the same foraging patch may
lead to prey depletion and/or the prey distribution and the
density may have changed over time, thereby resulting in site
fidelity being a sub-optimal foraging strategy (Pichegru etal.
2010; McIntyre etal. 2017; McHuron etal. 2018). Thus,
this illustrates a trade-off between a conservative strategy
of sticking to what one already knows and another riskier
strategy of switching and searching for new and potentially
more profitable foraging patches.
Income-breeding marine predators provisioning off-
spring (Houston etal. 2007), such as fur seals (Staniland and
Boyd 2003), sea lions (Womble etal. 2009), and seabirds
(Croll etal. 2006; Rayner etal. 2010), can be considered as
Responsible Editor: D.E. Crocker.
Reviewed by B. Abrahms and undisclosed experts.
Electronic supplementary material The online version of this
article (https :// 7-020-03685 -y) contains
supplementary material, which is available to authorized users.
* Dahlia Foo
1 Institute forMarine andAntarctic Studies, University
ofTasmania, Hobart, TAS7004, Australia
2 Sydney Institute ofMarine Science, Mosman, NSW2088,
3 Aquatic Sciences Centre, South Australian
Research andDevelopment Institute, WestBeach,
SouthAustralia5024, Australia
Content courtesy of Springer Nature, terms of use apply. Rights reserved.
... This relative measure tells us if an individual has more consistent behavior than the average for its population, but the statistic is not valid for other populations if mean consistency varies among populations. We used distance between consecutive foraging areas as an intuitive, biologically meaningful index (Carroll et al. 2018;Foo et al. 2020). ...
Seabirds must find food efficiently in the dynamic ocean environment to succeed at raising chicks. In theory, site familiarity, gained by prior experience in a place, should increase foraging efficiency when prey is predictable, and translate into increased reproductive success, though this is difficult to test empirically. To address this, we examined foraging-site fidelity in Magellanic penguins Spheniscus magellanicus using movement data from 180 individuals tracked during 23 breeding seasons when penguins make repeated trips from their colony to feed chicks. We tested whether chlorophyll-a concentration, as a proxy for ocean productivity, affects foraging-site fidelity. We then tested whether foraging-site fidelity affects foraging efficiency and reproductive success. Mean foraging-site fidelity was higher in years with higher ocean productivity, when fronts had stronger gradients in temperature and chlorophyll, and prey was likely more predictable. When returning to previously visited foraging sites, penguins arrived and returned faster than predicted for a trip of a given distance, leading to lower mean trip durations and more frequent trips in penguins with high site fidelity. Increased foraging efficiency and chick-feeding frequency in turn led to increased chick survival. Our study reveals that foraging efficiency is a key mechanism linking foraging-site fidelity and reproductive success.
... In contrast, the second scenario could potentially be more relevant for common dolphins that live in protected habitats in which extreme climatic events, such as marine heatwaves, could lead to high mortalities of prey species (e.g., [141]) and alteration of spawning times (e.g., [92,142]). Moreover, changes in temperature and nutrients of waters masses could lead to low abundance and redistribution of prey species (e.g., [143,144]). For dolphin species that inhabit protected environments, epizootic events often coincide with these types of extreme climatic stressors, leading to negative impacts on population health and reproduction, and occasionally large morbidity and mortality events (e.g., [40,43,145]). ...
Full-text available
Background High levels of standing genomic variation in wide-ranging marine species may enhance prospects for their long-term persistence. Patterns of connectivity and adaptation in such species are often thought to be influenced by spatial factors, environmental heterogeneity, and oceanographic and geomorphological features. Population-level studies that analytically integrate genome-wide data with environmental information (i.e., seascape genomics) have the potential to inform the spatial distribution of adaptive diversity in wide-ranging marine species, such as many marine mammals. We assessed genotype-environment associations (GEAs) in 214 common dolphins ( Delphinus delphis ) along > 3000 km of the southern coast of Australia. Results We identified 747 candidate adaptive SNPs out of a filtered panel of 17,327 SNPs, and five putatively locally-adapted populations with high levels of standing genomic variation were disclosed along environmentally heterogeneous coasts. Current velocity, sea surface temperature, salinity, and primary productivity were the key environmental variables associated with genomic variation. These environmental variables are in turn related to three main oceanographic phenomena that are likely affecting the dispersal of common dolphins: (1) regional oceanographic circulation, (2) localised and seasonal upwellings, and (3) seasonal on-shelf circulation in protected coastal habitats. Signals of selection at exonic gene regions suggest that adaptive divergence is related to important metabolic traits. Conclusion To the best of our knowledge, this represents the first seascape genomics study for common dolphins (genus Delphinus ). Information from the associations between populations and their environment can assist population management in forecasting the adaptive capacity of common dolphins to climate change and other anthropogenic impacts.
... Foraging trip metrics and movement patterns may also be related to other oceanographic influences such as current speeds, eddies and upwelling cells, which vary substantially along the South African coast (Roberson et al. 2017). Although the spatial distribution and foraging strategies of pinnipeds are often related to environmental influences (Foo et al. 2019(Foo et al. , 2020, other factors such as competition may also be im plicated, particularly at smaller spatial scales (Wege et al. 2019). Thus, the longer foraging trips observed for animals from Kleinsee and False Bay could be linked to higher levels of intra-specific competition at these larger colonies and may reflect strategies of resource partitioning (e.g. ...
Knowledge of animal foraging behaviour has implications for management and conservation. While Cape fur seals Arctocephalus pusillus pusillus comprise a major proportion of the southern African marine predator biomass, little is known about their at-sea movements. We investigated foraging distribution, habitat use and diving behaviour for 35 adult female Cape fur seals from 3 breeding colonies experiencing contrasting oceanographic regimes. Animals from Black Rocks, the smallest and eastern-most colony, undertook shorter foraging trips and utilised shallower waters over the shelf. In comparison, animals from the larger west coast colonies, at Kleinsee and False Bay, travelled further and utilised deeper shelf and shelf-slope waters. However, across colonies, females typically preferred depths of <500 m and slopes of <5°. Kleinsee and False Bay seals selected sea surface temperatures within the range typically preferred by pelagic prey species such as round herring, sardine and anchovy (14-19°C). Black Rocks individuals showed bimodal preferences for colder (16°C) and warmer waters (>22°C). Dive behaviour was similar between Kleinsee and False Bay individuals (unavailable from Black Rocks), with both pelagic and benthic foraging evident. Diel patterns were apparent at both sites, as dive depth and benthic diving increased significantly during daylight hours, likely reflecting vertical movements of prey species. We provide the first assessment of Cape fur seal movement behaviour for the South African component of the population. Observed geographic differences likely reflect the availability of suitable habitat but may also indicate differences in foraging strategies and density-dependent effects throughout the range of this species.
Full-text available
Long-nosed fur seals (Arctocephalus forsteri) were tagged as pups in colonies on Kangaroo Island, South Australia in eight consecutive pupping seasons from 1988–89 to 1995–96. Thirty-nine tagged animals were sighted on the southern Australian coast, being 0.89% of those tagged. They were aged from 9 months to 14 years 6 months, with half in their second and third years. Most records (88%) were of animals that moved eastwards. The most distant records were from Sydney in the east (1700 km), south of Tasmania in the south (1240 km) and Head of Bight in the west (700 km). One animal was seen twice, both times on the north coast of Kangaroo Island, once underwater and two years later ashore. Satellite telemetry studies of juvenile A. forsteri from Kangaroo Island showed that they typically forage in pelagic waters ~1000 km further south in association with the subtropical front. The study reported here shows that some animals tagged as pups disperse widely as juveniles around the southern Australian coast. The possibility of genetic interchange between breeding colonies is suggested by sightings of three tagged females aged 4 years and older at non-natal colonies.
Full-text available
Marine predators frequently exhibit consistency in foraging behaviors despite the dynamic nature of marine ecosystems, which has the potential for ecological and evolutionary implications depending on the timescale at which it persists. We examined behavioral consistency in movements and diving behavior of adult female California sea lions (Zalophus californianus), which are abundant, generalist central-place foragers inhabiting an ecosystem characterized by small- and broad-scale oceanographic variability. We used biologging devices to measure repeatability of behavior within a season and stable isotope analysis of whiskers to quantify behavior across a 2-year period associated with anomalous environmental conditions that affected prey availability. Sea lions were significantly repeatable in all variables across multiple timescales (Radj = 0.26–0.82), although repeatability estimates were generally higher for variables related to characteristics of individual dives (e.g., dive depth) than those that described dive bouts (e.g., bout duration) or spatial use (e.g., volume of 3D utilization distribution). These differences may result from the fact that diving behaviors vary with prey type, whereas spatial use and bout variables may reflect the foraging success within prey patches or movement among patches. There was variation in how predictable individual sea lions were in their diving behaviors, which was largely unrelated or negatively related to foraging site fidelity. The strength of behavioral consistency decreased with time yet persisted across the 2-year period, suggesting that while sea lions alter their behavior in response to environmental change, the behavioral flexibility of individuals may ultimately be constrained by consistency.
Central place foragers often change their foraging behaviour in response to changes in prey availability in the environment. Lactating Long-nosed fur seals (LNFS; Arctocephalus forsteri) at Cape Gantheaume in South Australia have been observed to display alternate foraging strategies where they forage on the shelf in summer and switch to oceanic foraging in winter. We investigated the relationship between changes in shelf summertime upwelling and the timing and variability when females switch from predominantly shelf to oceanic foraging. Geolocation tags were deployed on females from summer to winter in 2016 and 2017, giving us longitudinal tracks over the transition period. The timing of switching from shelf to oceanic foraging was primarily driven by seasonal oceanographic changes on the shelf – specifically when the strength of the seasonal localised upwelling began to decline. The individual variability in the timing of the switch was driven by the strength of the coastal upwelling with variability being greater in years when upwelling strength was weaker. By comparing our results to that of previous studies on the same colony, we found qualitative evidence that inter-annual environmental variability likely influences whether individuals display a single or multiple foraging strategies. This further highlights the flexibility in foraging strategies used by LNFS in response to environmental changes. The effect of inter-annual differences in foraging strategies on overall reproductive success warrants further investigation.
The ocean circulation in the Great Australian Bight (GAB) is dominated by the surface-intensified Leeuwin Current (LC) over the outer continental shelf, and the Flinders Current farther offshore. In the GAB, the LC flows eastwards and varies seasonally, with strongest currents of up to 0.8 m/s (at 130.5°E), bringing warm and salty waters as far east as western Tasmania. The Flinders Current flows westwards, as an undercurrent at depths of around 500 m over the continental slope and at the surface offshore of the LC. Off the shelf, the GAB is rich in mesoscale eddies, with surface-intensified currents of up to 0.4 m/s that are coherent over the full water depth (getting weaker with depth). Within deep-water eddies, isotherms are displaced vertically by up to 200 m. Eddies in the eastern GAB are most energetic in austral winter and spring - coincident with the seasonal weakening of the LC. The eastern-most “penetration” of GAB eddies occurs in austral winter - when the LC starts to weaken. We hypothesise that the horizontal shear associated with the LC generates eddies in the eastern GAB. The volume transport of the LC at the head of the GAB is typically between 1 and 7 Sv, with a clear seasonal cycle, and the interannual variability of LC transport is up to 2 Sv.
How animal movement decisions interact with the distribution of resources to shape individual performance is a key question in ecology. However, links between spatial and behavioural ecology and fitness consequences are poorly understood because the outcomes of individual resource selection decisions, such as energy intake, are rarely measured. In the open ocean, mesoscale features (approx. 10-100 km) such as fronts and eddies can aggregate prey and thereby drive the distribution of foraging vertebrates through bottom-up biophysical coupling. These productive features are known to attract predators, yet their role in facilitating energy transfer to top-level consumers is opaque. We investigated the use of mesoscale features by migrating northern elephant seals and quantified the corresponding energetic gains from the seals' foraging patterns at a daily resolution. Migrating elephant seals modified their diving behaviour and selected for mesoscale features when foraging. Daily energy gain increased significantly with increasing mesoscale activity, indicating that the physical environment can influence predator fitness at fine temporal scales. Results show that areas of high mesoscale activity not only attract top predators as foraging hotspots, but also lead to increased energy transfer across trophic levels. Our study provides evidence that the physical environment is an important factor in controlling energy flow to top predators by setting the stage for variation in resource availability. Such understanding is critical for assessing how changes in the environment and resource distribution will affect individual fitness and food web dynamics.
The distribution of marine predators is driven by the distribution and abundance of their prey; areas preferred by multiple marine predator species should therefore indicate areas of ecological significance. The Southern Ocean supports large populations of seabirds and marine mammals and is undergoing rapid environmental change. The management and conservation of these predators and their environment relies on understanding their distribution and its link with the biophysical environment, as the latter determines the distribution and abundance of prey. We addressed this issue using tracking data from 14 species of marine predators to identify important habitat.
Individual behavioural specialisation has far-reaching effects on fitness and population persistence. Theory predicts that unconditional site fidelity, that is fidelity to a site independent of past outcome, provides a fitness advantage in unpredictable environments. However, the benefits of alternative site fidelity strategies driving intraspecific variation remain poorly understood and have not been evaluated in different environmental contexts. We show that contrary to expectation, strong and weak site fidelity strategies in migratory northern elephant seals performed similarly over 10 years, but the success of each strategy varied interannually and was strongly mediated by climate conditions. Strong fidelity facilitated stable energetic rewards and low risk, while weak fidelity facilitated high rewards and high risk. Weak fidelity outperformed strong fidelity in anomalous climate conditions, suggesting that the evolutionary benefits of site fidelity may be upended by increasing environmental variability. We highlight how individual behavioural specialisation may modulate the adaptive capacity of species to climate change.
Long-term fidelity to foraging areas may have fitness benefits to individuals, particularly in unpredictable environments. However, such strategies may result in short-term energetic losses and delay responses to fast environmental changes. We used satellite tracking data and associated diving data to record the habitat use of nine individual southern elephant seals over 34 winter migrations. By assessing overlap in two- and three-dimensional home ranges we illustrate strong long-term (up to 7-year) fidelity to foraging habitat. Furthermore, a repeatability statistic and hierarchical clustering exercise provided evidence for individual specialization of foraging migration strategies.We discuss the possible influences of stable long-term foraging migration strategies on the adaptability of individual elephant seals to rapid environmental change. Our results further illustrate the need for more long-term longitudinal studies to quantify the influence of individual-level site familiarity, fidelity and specialization on population-level resource selection and population dynamics.
Although some associations between the leatherback turtle Dermochelys coriacea and the Gulf Stream current have been previously suggested, no study has to date demonstrated strong affinities between leatherback movements and this particular frontal system using thorough oceanographic data in both the horizontal and vertical dimensions. The importance of the Gulf Stream frontal system in the selection of high residence time (HRT) areas by the North Atlantic leatherback turtle is assessed here for the first time using state-of-the-art ocean reanalysis products. Ten adult females from the Eastern French Guianese rookery were satellite tracked during post-nesting migration to relate (1) their horizontal movements to physical gradients (Sea Surface Temperature (SST), Sea Surface Height (SSH) and filaments) and biological variables (micronekton and chlorophyll a), and (2) their diving behaviour to vertical structures within the water column (mixed layer, thermocline, halocline and nutricline). All the turtles migrated northward towards the Gulf Stream north wall. Although their HRT areas were geographically remote (spread between 80-30°W and 28-45°N), all the turtles targeted similar habitats in terms of physical structures, i.e. strong gradients of SST, SSH and a deep mixed layer. This close association with the Gulf Stream frontal system highlights the first substantial synchronization ever observed in this species, as the HRTs were observed in close match with the autumn phytoplankton bloom. Turtles remained within the enriched mixed layer at depths of 38.5±7.9 m when diving in HRT areas, likely to have an easier access to their prey and maximize therefore the energy gain. These depths were shallow in comparison to those attained within the thermocline (82.4±5.6 m) while crossing the nutrient-poor subtropical gyre, probably to reach cooler temperatures and save energy during the transit. In a context of climate change, anticipating the evolution of such frontal structure under the influence of global warming is crucial to ensure the conservation of this vulnerable species.