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Baleen whales are key consumers in marine habitats that serve as vectors of nutrients, but their populations have been slow to recover from past commercial whaling due to their low reproductive rates and ongoing anthropogenic threats. Climate impacts have become central to the demography and habitat use of baleen whales, and conservation efforts must account for these impacts to be effective. However, knowledge of baleen whale climate responses is lacking, and current survey effort is insufficient to capture changes in migration and habitat use for many species. Due to their unique combination of ecological and life history characteristics, baleen whales are particularly vulnerable to climate change and their climate responses should be expected to differ fundamentally from those of other marine consumers. These characteristics include the need for both large quantities and high densities of prey, the need to accumulate large energy reserves seasonally, as well as highly migratory movements and the reliance on high-latitude foraging areas with narrow seasonal windows in resource availability. Climate responses in baleen whales may involve abrupt changes in foraging habitat in contrast to more gradual poleward shifts observed in other species, changes in the timing, extent or tendency for migration, and changes in energy accumulation or fitness. Recognizing that climate impacts may differ from other species is critical to measuring and anticipating changes to baleen whale populations in the face of ongoing climate change, and to effectively managing their populations in the future. North Atlantic right whales (Eubalena glacialis), arguably the best studied baleen whale species at a population scale, exemplify expectations for baleen whale climate responses and the implications for future management and conservation. Right whales have shown abrupt changes to traditional patterns of habitat use and migratory behavior, with major implications for the effectiveness of existing protections. Understanding and detecting baleen whale climate responses and effectively guiding management in the face of ongoing change will require increased survey effort and novel methods to survey remote habitats; improved knowledge of mechanisms of prey aggregation and climate impacts on these processes; and continued development and refinement of mechanistic models and dynamic management strategies. 

Background Albatrosses can commute long distances to feed during the breeding season by avoiding energetically costly flapping flight. Energy from both wind and waves can be used to sustain soaring and reduce flapping flight, yet most studies of albatross flight have focused solely on the influence of wind. Methods To examine how wind and waves allow albatrosses to reduce energetic costs by limiting flapping flight, we analyzed how the flap rates of five albatross species (370 individuals) across two ocean basins varied with wind speed and swell height. Results For all study species, soaring using both wind and waves resulted in an 89–93% reduction in the number of flaps per hour and thus more energetically efficient flight. We found notable differences in the relative importance of wind and waves for albatrosses breeding in the Southern Ocean and North Pacific. The flap rates of Southern Ocean species, black-browed (Thalassarche melanophris), grey-headed (T. chrysostoma), and wandering (Diomedea exulans) albatrosses, were better explained by variability in windspeed whereas those of North Pacific species, black-footed (Phoebastria nigripes) and Laysan (P. immutabilis) albatrosses, were better explained by variability in swell height. Conclusions Our results suggest that Southern Ocean species relied more on dynamic soaring by exploiting winds whereas North Pacific species relied more on wave-slope soaring using swells. This divergence in behavior is likely the result of differences in the regional winds and swells between the two ocean basins. Although windspeeds experienced by albatrosses in both oceans were similar, North Pacific species experienced greater swell heights, likely allowing them to extract more wind energy from waves than albatrosses in the Southern Ocean. Our research highlights the importance of both wind and waves for albatross movement and the need to better understand environmental impacts on physiological drivers of foraging energetics to assess responses of seabirds to a rapidly changing climate. 

Abstract Wind is a major factor driving seabird movement and energetics, the effects of which are modulated by morphology. Developments in tagging technology now make it possible to test predictions from aerodynamic theory about the effects of wind on flight performance in free‐ranging birds. Waves are also thought to have a strong influence on seabird movement but have received less attention.We investigated the interplay between wind, waves, and morphology and tested predictions of flight theory in giant petrels (Macronectesspp.), which show greater sexual size dimorphism than any other seabird. We quantified flapping rates as a proxy of energy expenditure using accelerometers deployed on northern giant petrels (M. halli;n = 45) and southern giant petrels (M. giganteus;n = 48) breeding at Bird Island, South Georgia in 2022 and 2023. Wind and waves experienced by birds tracked with Global Positioning System (GPS) loggers were integrated with ERA5 reanalysis data to assess how flapping rates and ground speeds, respectively, were influenced by wind and waves. Using generalized additive mixed models, we predicted the spatial distribution of suitable habitat for soaring based on wind and wave conditions.Both wind and waves strongly influenced flight energetics; flapping rates decreased with increasing wind speed and swell height in all species and sexes. Together, wind and waves allowed giant petrels to reduce flapping rates by 76% to 91%. Wind also influenced the speed of travel; ground speed increased with wind speed in tail‐ and crosswinds, but generally decreased with wind speed in headwinds.Male giant petrels had higher wing loadings, and as predicted by flight theory, required higher air speeds for soaring flight and had higher flapping rates than females. Potential soaring habitat was much more limited for male than for female giant petrels, suggesting that differences in flight energetics between sexes may contribute to sexual segregation in foraging areas.Our results demonstrate how morphology, wind and waves combine to influence the flight energetics of giant petrels. Understanding the interactions among these factors is central to understanding environmental drivers of seabird distribution and to predicting responses to continued climate change. Read the freePlain Language Summaryfor this article on the Journal blog. 

ABSTRACT Estimates of movement costs are essential for understanding energetic and life-history trade-offs. Although overall dynamic body acceleration (ODBA) derived from accelerometer data is widely used as a proxy for energy expenditure (EE) in free-ranging animals, its utility has not been tested in species that predominately use body rotations or exploit environmental energy for movement. We tested a suite of sensor-derived movement metrics as proxies for EE in two species of albatrosses, which routinely use dynamic soaring to extract energy from the wind to reduce movement costs. Birds were fitted with a combined heart-rate, accelerometer, magnetometer and GPS logger, and relationships between movement metrics and heart rate-derived V̇O2, an indirect measure of EE, were analyzed during different flight and activity modes. When birds were exclusively soaring, a metric derived from angular velocity on the yaw axis provided a useful proxy of EE. Thus, body rotations involved in dynamic soaring have clear energetic costs, albeit considerably lower than those of the muscle contractions required for flapping flight. We found that ODBA was not a useful proxy for EE in albatrosses when birds were exclusively soaring. As albatrosses spend much of their foraging trips soaring, ODBA alone was a poor predictor of EE in albatrosses. Despite the lower percentage of time flapping, the number of flaps was a useful metric when comparing EE across foraging trips. Our findings highlight that alternative metrics, beyond ODBA, may be required to estimate energy expenditure from inertial sensors in animals whose movements involve extensive body rotations. 

Climate change is redistributing biodiversity globally and distributional shifts have been found to follow local climate velocities. It is largely assumed that marine endotherms such as cetaceans might shift more slowly than ectotherms in response to warming and would primarily follow changes in prey, but distributional shifts in cetaceans are difficult to quantify. Here we use data from fisheries bycatch and strandings to examine changes in the distribution of long-finned pilot whales (Globicephala melas), and assess shifts in pilot whales and their prey relative to climate velocity in a rapidly warming region of the Northwest Atlantic. We found a poleward shift in pilot whale distribution that exceeded climate velocity and occurred at more than three times the rate of fish and invertebrate prey species. Fish and invertebrates shifted at rates equal to or slower than expected based on climate velocity, with more slowly shifting species moving to deeper waters. We suggest that traits such as mobility, diet specialization, and thermoregulatory strategy are central to understanding and anticipating range shifts. Our findings highlight the potential for trait-mediated climate shifts to decouple relationships between endothermic cetaceans and their ectothermic prey, which has important implications for marine food web dynamics and ecosystem stability. 

Abstract Background Inertial measurement units (IMUs) with high-resolution sensors such as accelerometers are now used extensively to study fine-scale behavior in a wide range of marine and terrestrial animals. Robust and practical methods are required for the computationally-demanding analysis of the resulting large datasets, particularly for automating classification routines that construct behavioral time series and time-activity budgets. Magnetometers are used increasingly to study behavior, but it is not clear how these sensors contribute to the accuracy of behavioral classification methods. Development of effective  classification methodology is key to understanding energetic and life-history implications of foraging and other behaviors. Methods We deployed accelerometers and magnetometers on four species of free-ranging albatrosses and evaluated the ability of unsupervised hidden Markov models (HMMs) to identify three major modalities in their behavior: ‘flapping flight’, ‘soaring flight’, and ‘on-water’. The relative contribution of each sensor to classification accuracy was measured by comparing HMM-inferred states with expert classifications identified from stereotypic patterns observed in sensor data. Results HMMs provided a flexible and easily interpretable means of classifying behavior from sensor data. Model accuracy was high overall (92%), but varied across behavioral states (87.6, 93.1 and 91.7% for ‘flapping flight’, ‘soaring flight’ and ‘on-water’, respectively). Models built on accelerometer data alone were as accurate as those that also included magnetometer data; however, the latter were useful for investigating slow and periodic behaviors such as dynamic soaring at a fine scale. Conclusions The use of IMUs in behavioral studies produces large data sets, necessitating the development of computationally-efficient methods to automate behavioral classification in order to synthesize and interpret underlying patterns. HMMs provide an accessible and robust framework for analyzing complex IMU datasets and comparing behavioral variation among taxa across habitats, time and space.