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- Data packageData from: Behavioural flexibility in an Arctic seabird using two distinct marine habitats to survive the energetic constraints of winter(2022-11-08) Patterson, Allison; Gilchrist, H. Grant; Robertson, Gregory J.; Hedd, April; Fifield, David A.; Elliott, Kyle H.Background: Homeothermic marine animals in Polar Regions face an energetic bottleneck in winter. The challenges of short days and cold temperatures are exacerbated for flying seabirds with small body size and limited fat stores. We use biologging approaches to examine how habitat, weather, and moon illumination influence behaviour and energetics of a marine bird species, thick-billed murres (Uria lomvia). Methods: We used temperature-depth-light recorders to examine strategies murres use to survive winter in the Northwest Atlantic, where contrasting currents create two distinct marine habitats: cold (−0.1 ± 1.2 °C), shallower water along the Labrador Shelf and warmer (3.1 ± 0.3 °C), deep water in the Labrador Basin. Results: In the cold shelf water, murres used a high-energy strategy, with more flying and less diving each day, resulting in high daily energy expenditure and also high apparent energy intake; this strategy was most evident in early winter when day lengths were shortest. By contrast, murres in warmer basin water employed a low-energy strategy, with less time flying and more time diving under low light conditions (nautical twilight and night). In warmer basin water, murres increased diving at night when the moon was more illuminated, likely taking advantage of diel vertically migrating prey. In warmer basin water, murres dove more at night and foraging efficiency increased under negative North Atlantic Oscillation (calmer ocean conditions). Conclusions: The proximity of two distinct marine habitats in this region allows individuals from a single species to use dual (low-energy/high-energy) strategies to overcome winter energy bottlenecks.
- Data packageData from: Prey capture and selection throughout the breeding season in a deep-diving generalist seabird, the thick-billed murre(2019-07-18) Brisson-Curadeau, Émile; Elliott, Kyle H.Generalist seabirds forage on a variety of prey items providing the opportunity to monitor diverse aquatic fauna simultaneously. For example, the coupling of prey consumption rates and movement patterns of generalist seabirds might be used to create three‐dimensional prey distribution maps (‘preyscapes’) for multiple prey species in the same region. However, the complex interaction between generalist seabird foraging behaviour and the various prey types clouds the interpretation of such preyscapes, and the mechanisms underlying prey selection need to be understood before such an application can be realized. Central place foraging theory provides a theoretical model for understanding such selectivity by predicting that larger prey items should be 1) selected farther from the colony and 2) for chick‐feeding compared with self‐feeding, but these predictions remain untested on most seabird species. Furthermore, rarely do we know how foraging features such as handling time, capture methods or choice of foraging location varies among prey types. We used three types of animal‐borne biologgers (camera loggers, GPS and depth‐loggers) to examine how a generalist Arctic seabird, the thick‐billed murre Uria lomvia, selects and captures their prey throughout the breeding season. Murres captured small prey at all phases of a dive, including while descending and ascending, but captured large fish mostly while ascending, with considerably longer handling times. Birds captured larger prey and dove deeper during chick‐rearing. As central place foraging theory predicted, birds travelling further also brought bigger prey items for their chick. The location of a dive (distance from colony and distance to shore) best explained which prey type was the most likely to get caught in a dive, and we created a preyscape surrounding our study colony. We discuss how these findings might aid the use of generalist seabirds as bioindicators.
- Data packageData from: Northwest range shifts and shorter wintering period of an Arctic seabird in response to four decades of changing ocean climate(2021-11-29) Patterson, Allison; Gilchrist, H. Grant; Gaston, Anthony; Elliott, Kyle H.Climate change is altering the marine environment at a global scale, with some of the most dramatic changes occurring in Arctic regions. These changes may affect the distribution and migration patterns of marine species throughout the annual cycle. Species distribution models have provided detailed understanding of the responses of terrestrial species to climate changes, often based on observational data; biologging offers the opportunity to extend those models to migratory marine species that occur in marine environments where direct observation is difficult. We used species distribution modelling and tracking data to model past changes in the non-breeding distribution of thick-billed murres Uria lomvia from a colony in Hudson Bay, Canada, between 1982 and 2019. The predicted distribution of murres shifted during fall and winter. The largest shifts have occurred for fall migration, with range shits of 211 km west and 50 km north per decade, compared with a 29 km shift west per decade in winter. Regions of range expansions had larger declines in sea ice cover, smaller increases in sea surface temperature, and larger increases in air temperature than regions where the range was stable or declining. Murres migrate in and out of Hudson Bay as ice forms each fall and melts each spring. Habitat in Hudson Bay has become available later into the fall and earlier in the spring, such that habitat in Hudson Bay was available for 21 d longer in 2019 than in 1982. Clearly, marine climate is altering the distribution and annual cycle of migratory marine species that occur in areas with seasonal ice cover.