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Sampling locations for bowhead whale Balaena mysticetus skin samples (outliers excluded) in the eastern Canadian Arctic
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The eastern Canada-West Greenland (EC-WG) bowhead whale Balaena mysticetus population is slowly recovering from the intensive commercial whaling of the 18th and 20th centuries. However, climate change, through effects on ice conditions and prey availability, is one of several threats that might affect bowhead whale recovery. In this study, we explo...
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... et al. 2003). Their winter distribution includes Hudson Strait, northern Hudson Bay, east Baffin Island and the ice edge along West Greenland (Reeves & Heide-Jørgensen 1996, Koski et al. 2006), while in spring they are usually found along the west coast of Greenland (e.g. Disko Bay), in Cumberland Sound, Foxe Basin and Lancaster Sound (see Fig. 1). Their summer range in cludes the fjords and bays of the Canadian High Arctic, Hudson Bay and Foxe Basin ( Cosens et al. 1997, Cosens & Innes 2000, Higdon & Ferguson ...
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... and satellite telemetry studies indicate sig- nificant sex and age class segregation within the EC- WG population, at least at times other than winter (Ferguson et al. 2010a, Heide-Jørgensen et al. 2003, 2006) (see Fig. 1). For instance, Disko Bay is an important feeding area for adult bow- head whales, and the vast majority of whales aggre- gating there in the spring are large adult females (>14 m) ( Laidre et al. 2008). In summer, Foxe Basin is used mainly by juvenile whales and females with their calves (Cosens & Blouw 2003), whereas the Gulf of ...
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... whale skin samples (n = 202) were col- lected between June and September from 1988 to 2009 at several locations of the Canadian eastern Arctic including Foxe Basin, Admiralty Inlet, Cum- berland Sound and Hudson Strait (Fig. 1, Table 1). However, the vast majority of the whales included in this study were sampled in July and August (> 94%) in Foxe Basin (84%) ( Table 1). Samples were ob - tained using a crossbow darting system ( Brown et al. 1991), and were preserved frozen at −20°C until iso- topic analyses. Information on age class was col- lected directly in the ...
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... samples were collected in July 2007 and September 2009 on board Canadian Coast Guard icebreakers at 24 locations in the Canadian eastern Arctic, including the Labrador Sea, Davis Strait, Baffin Bay and the Canadian Arctic Archipel- ago ( Fig. 1). A complete description of the sampling protocol is presented in Pomerleau et al. (2011c). Briefly, samples were collected with a Bongo net, a set of 2 adjacent 1 m 2 framed nets (mesh size 2 × 236 µm), towed verti- cally from 100 m (or near the bottom if sampling was done in a shallower area) to the surface at a speed of 1 m s −1 . ...
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... into 4 ml glass vials and kept frozen at −20°C until analysis. Pomerleau et al. (2011c) defined 4 biogeographic domains within the EC-WG bowhead whale distribution range, which were characterized by specific prey assemblages and water mass characteristics. These regions included Davis Strait, Baffin Bay, Lan- caster Sound and the Gulf of Boothia (Fig. 1). Marine zooplankton stable isotope data from this study were used as sources in a mixing model along with additional data from the literature ( Hobson 1993, Hobson et al. 2002. Since bowhead whales may ...
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Citations
... During summer, ECWG bowhead whales are found in bays and fjords in the Canadian High Arctic, such as the Gulf of Boothia, Foxe Basin, eastern Baffin Island, and as far south as Hudson Bay (Cosens & Innes, 2000;Cosens et al., 1997;Ferguson et al., 2010;Higdon & Ferguson, 2010;Pomerleau et al., 2011). Bowhead whales feed on zooplankton (e.g., calanoid copepods ;Fortune et al., 2020b,c;Pontbriand et al., 2023), primarily during late summer through autumn (e.g., Finley, 2001;Pomerleau et al., 2011Pomerleau et al., , 2012. However, stable isotope analysis and movement data from tagged whales have revealed that bowhead whales likely feed year-round, although at a lower rate in winter Matthews & Ferguson, 2015;Pomerleau et al., 2018). ...
Climate change poses new challenges to Arctic marine mammals, with increasing vessel traffic and associated underwater noise pollution emerging as significant threats. The bowhead whale ( Balaena mysticetus ), an endemic Arctic cetacean, faces these new threats. The Eastern Canada‐West Greenland (ECWG) bowhead whale population migrates through areas with the highest levels of vessel traffic in the Canadian Arctic. Here, we document the spatial and temporal overlap between 36 satellite‐tagged ECWG bowhead whales and vessels equipped with Automatic Identification System (AIS) transponders during 2012–2017. We report 1,145 instances where vessels were within 125 km of a tagged whale, with 306 occurrences within distances ≤50 km. Overlap between vessels and tagged bowhead whales was quantified monthly within years to investigate individual whale encounter rates. Results indicate that ECWG bowhead whales encounter the majority (79%) of vessels annually during August–October, with the highest number of encounters (42%) observed in September. Encounter rates ranged from 0.25 to 0.51 vessels encountered per day per whale during August–October compared to <0.07 vessels per day in all other months in this study. To better inform conservation strategies, further research is required to assess bowhead whale behavioral responses relative to distance from vessels.
... Three key copepod species -Calanus glacialis, Calanus hyperboreus, and Metridia longaaccount for 50-80% of the biomass of Arctic zooplankton (Mumm et al., 1998;Darnis et al., 2008). The vertical migration of these species not only supplies carbon from the surface to the benthic region in Arctic marine ecosystems (Kosobokova and Hirche, 2009;Forest et al., 2011;Sampei et al., 2012) but can also affect the distributions of their major predators, such as fish (Boreogadus saida, Mallotus villosus) and whales (Balaena mysticetus) (Benoit et al., 2010;Pomerleau et al., 2012;Hop and Gjøsaeter, 2013;McNicholl et al., 2016). Therefore, it is important to accurately understand the vertical distributions of these key copepod species to gain insight into the interrelationships among organisms within the Arctic marine ecosystem. ...
Diel vertical migration (DVM) of zooplankton plays a vital role in biological carbon pump and food web interactions. However, there is considerable debate about the DVM of zooplankton in response to environmental changes in the Arctic Ocean. We investigated DVM behavior in the key Arctic copepods Calanus glacialis, Calanus hyperboreus, and Metridia longa following the midnight sun period in the East Siberian continental margin region. The two Calanus species showed non-DVM behaviors, whereas M. longa showed a typical DVM pattern consistent with the solar radiation cycle. Additionally, these species showed different vertical distributions. Calanus glacialis was distributed at depths above 20 m in the warm fresh water, where the highest density gradient was observed. Calanus hyperboreus was distributed at depths between 30 and 55 m in the cold salty water, where a high contribution of micro phytoplankton and the subsurface chlorophyll maximum (SCM) layer were observed. M. longa was found across a broader range of temperature and salinity than both Calanus species, and it was distributed in the upper water column, where the SCM layer was observed at night and at depths between 100 and 135 m in the daytime. These results imply that M. longa can be well adapted to the changing Arctic Ocean environment, where sea ice loss and ocean warming are ongoing, whereas C. hyperboreus can be the most vulnerable to these changes. These findings provide important information for understanding variations in the vertical distributions of key copepod species in the rapidly changing Arctic marine environment.
... Reeves et al. 1983), their dispersal potential and ability to shift their distribution to match that of their prey is considerable. For the EC-WG population, the variation in habitat use by different demographic groups in the population based on energetic requirements and predator avoidance (Cosens & Blouw 2003, Heide-Jørgensen et al. 2010, Fortune et al. 2020c, and the inter-individual diet variation ob served (Pomerleau et al. 2012(Pomerleau et al. , 2014 suggest spatial and dietary flexibility. ...
... To maximize filtering efficiency and prey acquisition while at depth, they periodically close their mouth, presumably to clean the baleen plates and swallow the prey (Simon et al. 2009) or to reduce drag when prey density is low (van der Hoop et al. 2019), before reopening it to continue filtering. Several studies have characterized the diet of EC-WG bowhead whales using stomach content analysis (Pomerleau & Ferguson 2011a, Fortune et al. 2020a, in situ prey sampling near foraging whales (Fortune et al. 2020a), stable isotope (SI) analysis (Pomerleau et al. 2012), and fatty acid analysis (Pomerleau et al. 2014). Results indicate that EC-WG bowhead whales mainly feed on large calanoid copepods such as C. gla cialis, C. hyperboreus, Metridia longa and Para euchateta spp., and that mysids (e.g. ...
... Mysis oculata) and euphausiids are secondary prey items. Pomerleau et al. (2012Pomerleau et al. ( , 2014 reported important inter-individual variability in diet, and cluster analyses in both studies revealed distinct groups within the population based on their SI ratios or fatty acid profiles. However, none of the groups were dominated by individuals from a specific region, year, sex, or age class, and, thus, the mechanism driving interindividual diet variation remained unknown. ...
Shifts in zooplankton quantity and quality caused by climate change could challenge the ability of bowhead whales to meet their energetic requirements. When facing such selection pressure, intra-population variation dampens the negative effects and provides population-level resilience. Previous studies observed inter-individual diet variation in bowhead whales, but the mechanism responsible for the variation was undetermined. We investigated foraging variability in Eastern Canada-West Greenland bowhead whales using dietary biomarkers (stable isotopes, fatty acids) and movement data (satellite telemetry with time-depth recorders) from the same individuals. We found that bowhead whale individuals using distinct summer and fall foraging habitats displayed differences in horizontal movements, foraging dive depth, and diet. For individuals using the Canadian Arctic Archipelago habitat (Foxe Basin, Gulf of Boothia, Prince Regent Inlet, Lancaster Sound and Admiralty Inlet, Nunavut), they performed long distance movements across regions, and their foraging dive depth was generally shallow, but increased from July to November. These whales displayed higher δ ¹³ C and δ ¹⁵ N values and ratios of C16:1n7/C16:0. Individuals using the West Baffin Bay habitat (Cumberland Sound, Baffin Bay, Davis Strait) were more localized in their horizontal movements and consistent over time in their foraging dive depth, which was generally deeper. These whales displayed lower δ ¹³ C and δ ¹⁵ N values and ratios of C16:1n7/C16:0. Overall, this inter-individual variation in diet and foraging behaviour could indicate some niche variation which would be beneficial for the population under changing habitats and prey availability.
... This finding is consistent with the Bering-Chukchi-Beaufort bowhead population that exploit prey aggregations near the sea bottom during fall (Olnes et al., 2020). To a lesser extent, shallow epipelagic dives during early summer may have also reflected consumption of mysids, euphausiids and chaetognaths (Pomerleau et al., 2012). ...
The ecological impact of environmental changes at high latitudes (e.g., increasing temperature, and decreased sea ice cover) on low-trophic species, such as bowhead whales, are poorly understood. Key to understanding the vulnerability of zooplanktivorous predators to climatic shifts in prey is knowing whether they can make behavioural or distributional adjustments to maintain sufficient prey acquisition rates. However, little is known about how foraging behaviour and associated environmental conditions fluctuate over space and time. We collected long-term movement (average satellite transmission days were 397 (± 204 SD) in 2012 and 484 (± 245 SD) in 2013) and dive behaviour data for 25 bowhead whales (Balaena mysticetus) equipped with time-depth telemetry tags, and used hierarchical switching-state-space models to quantify their movements and behaviours (resident and transit). We examined trends in inferred two-dimensional foraging behaviours based on dive shape of Eastern Canada-West Greenland bowhead whales in relation to season and sea ice, as well as animal sex and age via size. We found no differences with regards to whale sex and size, but we did find evidence that subsurface foraging occurs year-round, with peak foraging occurring in fall (7.3 hrs d⁻¹ ± 5.70 SD; October) and reduced feeding during spring (2.7 hrs d⁻¹ ± 2.55 SD; May). Although sea ice cover is lowest during summer foraging, whales selected areas with 65% (± 36.1 SD) sea ice cover. During winter, bowheads occurred in areas with 90% (± 15.5 SD) ice cover, providing some open water for breathing. The depth of probable foraging varied across seasons with animals conducting epipelagic foraging dives (< 200 m) during spring and summer, and deeper mesopelagic dives (> 400 m) during fall and winter that approached the sea bottom, following the seasonal vertical migration of lipid-rich zooplankton. Our findings suggest that, compared to related species (e.g., right whales), bowheads forage at relatively low rates and over a large geographic area throughout the year. This suggests that bowhead whales have the potential to adjust their behaviours (e.g., increased time allocated to feeding) and shift their distributions (e.g., occupy higher latitude foraging grounds) to adapt to climate-change induced environmental conditions. However, the extent to which energetic consumption may vary seasonally is yet to be determined.
... The effects of climate change on bowhead whale phenology, ecology, habitat selection, body condition, behaviour, and population dynamics have been the subject of considerable speculation (e.g. Burek et al., 2008;Pomerleau et al., 2012;Chambault et al., 2018;Fortune et al., 2020aFortune et al., , 2020b. Undoubtedly, change is already occurring in terms of, for example, ice conditions (reduced thickness and coverage, timing of break-up and freezeup), predation (from killer whales), and prey availability (from competition with other zooplanktivores as well as the relative productivity of various zooplankton species), and more change is on the way (Moore et al., 2019(Moore et al., , 2021Kovacs et al., 2020). ...
The history of bowhead whaling and hunt management in the eastern and central Canadian Arctic is reviewed. Subsistence hunting of bowhead whales by Inuit resumed in the 1990s under co-management arrangements that were part of land-claims settlement agreements. Removals by whaling in both Canada and Greenland have been accounted for in IWC Scientific Committee assessments of the Eastern Canada–West Greenland (EC-WG) stock, but Canada, having withdrawn from IWC membership in 1982, has no legal obligation to consider IWC management advice. From 1994-2021 the total reported catch of bowheads in the central and eastern Canadian Arctic was 39 (not including struck-and-lost whales or whales that died from incidental entanglement in fishing gear). Sixteen different communities, most of which had a long history of bowhead whaling prior to the arrival of commercial whalers, took at least one bowhead over that 27-year period. More than half of the recent catches have been by the communities of Igloolik, Sanijarak, Naujaat and Coral Harbour, all in the Foxe Basin–Repulse Bay–northern Hudson Bay region where at least occasional hunting of bowheads by local people had persisted until well into the 1970s. Greenland’s reported landed catches totaled from 2009-2015, with no successful hunts reported since 2015. Well over a third of the whales landed by both countries combined have been mature females, the most valuable class in terms of potential for population increase. Several factors in addition to hunting and entanglement in fishing gear are likely affecting EC-WG bowheads, including increased exposure to killer whale predation (linked to the massive reduction in sea ice) and other changes in ecological conditions driven primarily by climate change (e.g. more industrial activity, more vessel traffic, more noise). Recent analyses suggest the EC-WG stock of bowheads has grown considerably since the end of commercial whaling, with best estimates of current abundance in the range of 6000-7000 individuals. Even though the population appears capable of sustaining present levels of removal and disturbance, it is important for monitoring efforts to continue in both Canada and Greenland, with regular Indigenous participation. Local observations and traditional knowledge can be valuable sources of information on animal health, behaviour and phenology.
... and the pteropod Limacina helicina (Lubny-Gertsik, 1959;Itoh et al., 2014). All three species are prey items of several higher trophic level species, including bowhead whales (Lowry, 1993;Lowry et al., 2004;Pomerleau et al., 2011Pomerleau et al., , 2012Pomerleau et al., , 2014. Since the seasonal and inter-annual variations in the concentration of these zooplankton species, particularly the lipid rich copepod C. glacialis, are likely to play a major role for foraging bowhead whales and other higher trophic level species including fishes, marine birds and other marine mammals, it is critical to understand the linkages between the abundance of these key zooplankton species and the environmental conditions. ...
The foremost flooding event of the past century happened in 2013 on the Amur River, which flows into the Sea of Okhotsk. Concurrently, the winter of 2012–2013 was a year of heavy sea ice and delayed onset of melting in this region. To examine the joint effects of these major, regional-scale hydrological freshening events on oceanographic processes, we compared physical (CTD, tides and currents) and biological (zooplankton) data measured in 2004 and 2013 in Academy Bay, Sea of Okhotsk. Our results indicate that the difference in sea water temperature between the two years played a primary role in shaping zooplankton variability. Data collected in 2013 showed that water temperature was colder and that the upper layer was substantially fresher (∼4–5 psμ) than in 2004. This decrease in water temperature and salinity reduction was accompanied by a significant decrease in the abundance of some key zooplankton species including Calanus glacialis, Pseudocalanus spp. and Sagitta elegans and a corresponding increase in the abundance of Limacina helicina. Delayed melting of sea ice in 2013 potentially triggered a mismatch in pelagic production that may have impacted the recruitment of calanoid copepods. Variation in tidal and subtidal advection of cold and highly saline Okhotsk Sea shelf water appears to be an important process influencing regional variation in zooplankton abundance. The occurrence of such hydrological events has the potential to trigger cascading effects through the food web.
... Bowhead whales are specialized filter feeders, and may be at physiological risk if baleen plates are fouled by fuel oil or become entangled in nets or debris (Lambertson et al., 2005). Also, the warming of the Arctic is expected to favor smaller and leaner zooplankton species from more temperate waters, thus changing the food web which may result in bowhead whales, as zooplankton specialists, having to cope with changes in food quality and availability (Pomerleau et al., 2012;Fortune et al., 2020a). ...
Bowhead whales (Balaena mysticetus L., 1758) of the Eastern Canada-West Greenland population have been hunted by Inuit for millennia. Significant commercial harvests, conducted by European and American whalers for about 400 years, ended ca. 1915. A small co-managed subsistence harvest from this population has occurred inconsistently in Canada and Greenland, since 1996 and 2009, respectively. Since near extirpation from commercial whaling, population size has increased and the Inuit subsistence hunt now requires a harvest management framework that incorporates knowledge of abundance trends, population dynamics, and carrying capacity. Here, we use a model estimate of pre-commercial exploitation abundance to approximate carrying capacity and develop a management framework with reference points and corresponding stock status zones. When applied to recent abundance estimates, our framework indicates that the population is likely within the healthy (N50–N70) zone. Thus, an appropriate management objective is to support continued population increase, with concurrent marginal harvesting, while maintaining the population level above the target reference point (N70) of ca 12,000 whales. However, there remains large uncertainty about current population size and growth rate. The resulting data gaps require a plan for future research to monitor this population in the context of climate changes.
... One explanation is that migration is ubiquitous among high-latitude swimming mammals due to seasonal pulses of resources in summer followed by either constraints to food resources or ice coverage in winter (e.g. Pomerleau et al. 2012). Meanwhile, bats at high latitudes invariably migrate and/or hibernate to avoid winter resource limitations (e.g. ...
• Migration is ubiquitous among animals and has evolved repeatedly and independently. Comparative studies of the evolutionary origins of migration in birds are widespread, but are lacking in mammals. Mammalian species have greater variation in functional traits that may be relevant for migration. Interspecific variation in migration behaviour is often attributed to mode of locomotion (i.e. running, swimming, and flying) and body size, but traits associated with the evolutionary precursor hypothesis, including geographic distribution, habitat, and diet, could also be important predictors of migration in mammals. Furthermore, mammals vary in thermoregulatory strategies and include many heterothermic species, providing an alternative strategy to avoid seasonal resource depletion.
• We tested the evolutionary precursor hypothesis for the evolution of migration in mammals and tested predictions linking migration to locomotion, body size, geographic distribution, habitat, diet, and thermoregulation. We compiled a dataset of 722 species from 27 mammalian orders and conducted a series of analyses using phylogenetically informed models.
• Swimming and flying mammals were more likely to migrate than running mammals, and larger species were more likely to migrate than smaller ones. However, heterothermy was common among small running mammals that were unlikely to migrate. High-latitude swimming and flying mammals were more likely to migrate than high-latitude running mammals (where heterothermy was common), and most migratory running mammals were herbivorous. Running mammals and frugivorous bats with high thermoregulatory scope (greater capacity for heterothermy) were less likely to migrate, while insectivorous bats with high thermoregulatory scope were more likely to migrate.
• Our results indicate a broad range of factors that influence migration, depending on locomotion, body size, and thermoregulation. Our analysis of migration in mammals provided insight into some of the general rules of migration, and we highlight opportunities for future investigations of exceptions to these rules, ultimately leading to a comprehensive understanding of the evolution of migration.
... Many studies using SIA provide data that can be applied for conservation practices (e.g. Valenzuela et al. 2009, Pomerleau et al. 2012). Population and stock structure studies, which are fundamental for conservation and management (Boyd et al. 2010), have elucidated important particularities amongst diff erent stocks of the same species. ...
RESUMO A análise de isótopos estáveis (AIE) fornece informações sobre a produtividade do oceano e aspectos ecológicos de baleias relacionados ao uso do habitat e ecologia alimentar, estrutura de estoque, fi siologia e evolução. Foram revisados estudos publicados usando a AIE em baleias em todo o mundo entre novembro de 1979 e junho de 2017. Foram avaliadas lacunas nas áreas geográfi cas e heterogeneidade entre as espécies estudadas usando essa metodologia. Também investigamos quais tecidos foram mais utilizados para análise, as fontes de variação em valores de isótopos estáveis, a combinação desta metodologia com outras técnicas e como pode ser útil para a conservação deste táxon e dos ecossistemas marinhos. Um total de 63 publicações foi encontrado e foi possível detectar aumento no número de publicações, uma vez que 49% dos estudos foram realizados nos últimos 7 anos e meio do período analisado. Quase 55% dos estudos concentraram-se na ecologia de forrageio e no uso do habitat. As cerdas bucais foram o principal tecido analisado. Os estudos investigaram 14 espécies, sendo mais comuns aqueles relacionados a baleia-fi n, Balaenoptera physalus (N=19) e a baleia-da-Groenlândia, Balaena mysticetus (N=18). As metodologias de telemetria e AIE combinadas foram úteis para entender as variações geográfi cas em valores de isótopos estáveis. A metodologia pode também ter valor no cenário de mudanças climáticas fornecendo informações sobre plasticidade alimentar e amplitude de nicho de diferentes espécies, por exemplo. Apesar das incertezas relacionadas à distribuição dos valores de isótopos estáveis no mar e às taxas de incorporação em baleias, por exemplo, a AIE fornece informações ecológicas primordiais para o manejo e conservação desse grupo.
... Bowhead whales (Balaena mysticetus) feed on patchily distributed prey such as amphipods, copepods, cirripedes, gastropods, euphausiids and mysids in the eastern Arctic [1][2][3] . Like other large, zooplanktivorous predators, they must consistently locate energy-rich prey patches (e.g., North Atlantic right whales [4][5][6], which are in turn controlled by temperature, salinity, ice-formation and recession, phytoplankton availability, and mixing 7,8 . ...
... However, relatively little is known about the feeding behaviour and primary prey of bowhead whales throughout their range-particularly in Canadian waters. What is known about bowhead diet in the Eastern Canadian Arctic has come qualitatively from stomach content analysis from a few harvested animals 2 , or has been inferred from stable-isotope 3,18 and fatty acid 19 analysis. Eastern Canada-West Greenland (ECWG) bowhead whale diet and behaviour has only been well studied in the eastern limit of their range in Disko Bay (western Greenland). ...
As zooplanktivorous predators, bowhead whales (Balaena mysticetus) must routinely locate patches of prey that are energy-rich enough to meet their metabolic needs. However, little is known about how the quality and quantity of prey might influence their feeding behaviours. We addressed this question using a new approach that included: (1) multi-scale biologging and unmanned aerial system observations of bowhead whales in Cumberland Sound, Nunavut (Canada), and (2) an optical plankton counter (OPC) and net collections to identify and enumerate copepod prey species through the water column. The OPC data revealed two prey layers comprised almost exclusively of lipid-rich calanoid copepods. The deep layer contained fewer, but larger, particles (10% greater overall biomass) than the shallow prey layer. Dive data indicated that the whales conducted long deep Square-shaped dives (80% of dives; averaging depth of 260.4 m) and short shallow Square-shaped dives (16%; averaging depth of 22.5 m) to feed. The whales tended to dive proportionally more to the greater biomass of zooplankton that occurred at depth. Combining behavioural recordings with prey sampling showed a more complex feeding ecology than previously understood, and provides a means to evaluate the energetic balance of individuals under current environmental conditions.
