Abstract: Bio-logging is a methodological approach in which miniature data recording devices are temporarily attached to free-ranging animals to monitor their movement, behaviour and physiology, as well as the physical parameters of the environment directly surrounding the animals, turning them into bio-plateformes. Unsurprisingly bio-logging emerged from marine and polar studies where the monitoring of individuals in these harsh and remote places cannot be done using traditional approaches. Miniaturization and technological advances has meant that the range of species that can be instrumented, as well as the diversity of the questions that can be sought through bio-logging, are expanding fast. New sensors are constantly being developed, pushing further the limits of this field. Instrumented animals deliver information not only on their activities but also on the physical characteristics of the environments they go through. For instance, over the last two decades, loggers attached to deep diving seals have supplemented physical oceanographic measurements with hydrographic profiles from CTD loggers but also with new series of biological measurements. For examples, fluorescence and light sensors provided information on the concentration of phytoplankton in the euphotic layer; miniature echo sounders together with high sensitivity and fast responding light sensor to detect bioluminescence, brought considerable progress in detecting small size particles (>1-2 mm) such as marine snow, zooplankton, but also fish and squids and estimate their abundance.

Abstract: Tracking data of marine predators are increasingly used in marine spatial management. We developed a spatial data set with estimates of the monthly distribution of 6 pelagic seabird species breeding in the Northeast Atlantic. The data set was based on year-round global location sensor (GLS) tracking data of 2356 adult seabirds from 2006-2019 from a network of seabird colonies, data describing the physical environment and data on seabird population sizes. Tracking and environmental data were combined in monthly species distribution models (SDMs). Cross-validations were used to assess the transferability of models between years and breeding locations. The analyses showed that birds from colonies close to each other (<500 km apart) used the same nonbreeding habitats, while birds from distant colonies (>1000 km) used colony-specific and, in many cases, non-overlapping habitats. Based on these results, the SDM from the nearest model colony was used to predict the distribution of all seabird colonies lying within a species-specific cut-off distance (400-500 km). Uncertainties in the predictions were estimated by cluster bootstrap sampling. The resulting data set consisted of 4692 map layers, each layer predicting the densities of birds from a given species, colony and month across the North Atlantic. This data set represents the annual distribution of 23.5 million adult pelagic seabirds, or 87% of the Northeast Atlantic breeding population of the study species. We show how the data set can be used in population and spatial management applications, including the detection of population-specific nonbreeding habitats and identifying populations influenced by marine protected areas.

Abstract: Changing environmental conditions in the Arctic make it important to document and understand habitat preferences and flexibility of vulnerable high-latitude mammals. Indirect proxies are especially useful for elusive species, such as rodents. This study explores incisor microwear as an indicator of variation in behavior and microhabitat use in Siberian lemmings (Lemmus sibiricus) and narrow-headed voles (Lasiopodomys gregalis) from the Yamal Peninsula, Russia. Fifty-nine individuals were sampled at four sites along a latitudinal gradient from forest-tundra ecotone to high-Arctic tundra. Lemmings are present at the northernmost site, voles at the southernmost site, and both species at the middle two. Lemmus sibiricus prefers wet, mossy lowland, whereas La. gregalis favors drier thickets and more open microhabitats and burrows underground. Feature-based analyses indicate higher densities of features and more uniformly oriented striations for voles than lemmings at sites with both species. The species also differ significantly in microwear texture attributes suggesting larger features for lemmings, and smaller ones, but more of them, for voles. While no texture differences were found between sites within species, voles from sites with open tundra have higher striation densities than those from the forest-tundra ecotone. Furthermore, lemmings from open tundra sites have higher striation densities than those from the water-saturated, moss-covered northernmost site. While microhabitat preferences and burrowing by voles likely contribute to differences between species, variation within seems to reflect habitat variation given differences in abrasive loads between sites. This suggests that incisor microwear patterning can be used to track microhabitat differences among Arctic rodent populations.

Abstract: In colonially breeding marine predators, individual movements and colonial segregation are influenced by seascape characteristics. Tidewater glacier fronts are important features of the Arctic seascape and are often described as foraging hotspots. Albeit their documented importance for wildlife, little is known about their structuring effect on Arctic predator movements and space use. In this study, we tested the hypothesis that tidewater glacier fronts can influence marine bird foraging patterns and drive spatial segregation among adjacent colonies. We analysed movements of black-legged kittiwakes (Rissa tridactyla) in a glacial fjord by tracking breeding individuals from five colonies. Although breeding kittiwakes were observed to travel up to ca. 280 km from the colony, individuals were more likely to use glacier fronts located closer to their colony and rarely used glacier fronts located farther away than 18 km. Such variation in the use of glacier fronts created fine-scale spatial segregation among the four closest (ca. 7 km distance on average) kittiwake colonies. Overall, our results support the hypothesis that spatially predictable foraging patches like glacier fronts can have strong structuring effects on predator movements and can modulate the magnitude of intercolonial spatial segregation in central-place foragers.

Abstract: This study is based on the analysis of detailed measurements of firn dielectric properties performed in Antarctica through coring down to 106 m. Dielectric measurements in the frequency band (0.4–2.5 GHz) have been carried out using an open−resonator probe. Density was also measured for the same samples. The experimental results confirmed the well−known dependence of the real part of permittivity ε′ on depth and density, showing an increase of ε′ with density. The imaginary part also increases with depth with a rather complex dependence on frequency, probably due to the presence of salts or impurities. The analysis of the experimental data was performed by implementing 3D and 2D full wave numerical models, to simulate a mixture of firn crystals at prescribed densities, corresponding to the measured densities on the ice cores. The numerical analysis of the ensemble of inclusions showed that the usual symmetric formulae used for modeling ice dielectric properties agree with the average results of the simulation, but they are not able to explain the spreading of the measured data at given density. A dielectric model was then developed allowing for quantification of the dependence of dielectric properties on density, by combining two models: one consisting in firn crystals into an air host, the other assuming the presence of air inclusions into a homogeneous firn host. The weighted equation is based on the volume fraction. A simple geometric shape (ellipsoidal) is assumed for both ice crystals and air inclusions. This kind of shape is reasonable for the purpose of the dielectric study. The result is a mixture, smoothly changing from firn particles in air (low density) to air bubbles in an ice matrix (high density). A statistical analysis has been accomplished to investigate the dependence of the dielectric properties on the geometrical arrangement of the inclusions. For that purpose, a large number of simulations with different arrangements (micro−states) giving rise to the same average density (macro−states) has been carried out. The permittivity change due to micro−state variability appears to be at least two−three times the model variation due to density alone, and comparable to the measured variability at a given depth, suggesting that firn structure has a significant effect on the dielectric properties.