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Publisher's version (útgefin grein), Entanglement in fishing gear is a significant anthropogenic source of large whale injury and mortality. Although entanglements have been reported in the eastern North Atlantic, their frequency has not been previously estimated. This study used systematic scar analysis to estimate the frequency of non-lethal entanglements among individual humpback whales Megaptera novaeangliae off coastal Iceland, from 2005 through 2017. Images of the caudal peduncle and fluke insertions of 379 individuals were analyzed for wrapping injuries and notches known to be indicative of entanglement. The results indicated that at least 24.8% (n = 94, 95% confidence intervals [95% CI]: 20.5-29.1%) of individuals had a history of prior entanglement when first encountered. Depending on the metric used, the whales subsequently acquired new entanglement-related injuries at an average rate of 1.9% (95% CI: 0.6-3.2%) or 16.3% (95% CI: 3.0-29.3%) per year, with no statistically significant change over time. Furthermore, evidence suggests that at least some entanglements occurred locally. Observations of whales with gear still entangling the body confirmed the patterns of injury studied here. These results are lower than scar-based estimates from other parts of the world, but the cause of this difference requires further study. Scar-based methods underestimate the frequency of prior entanglement because some injuries heal beyond recognition, do not involve the caudal peduncle, and may occur on whales that die before they are studied. Long-term monitoring of humpback whale entanglement in Icelandic coastal waters is important for evaluating the local effects of fisheries, as well as the viability of the endangered Cape Verde breeding population., This work was funded in part by a National Geographic Explorer Grant awarded by the National Geographic Society, a PhD sponsorship grant awarded by Gentle Giants Whale Watching, and a Doctoral Grant awarded by Rannís Icelandic Research Fund. We thank all the students at the University of Iceland’s Húsavík Research Center for contributing data, the Faxaflói Ceta - cean Research volunteers (in Húsavík and Reykjavík), and all the whale-watching companies in Iceland who showed interest in the project and contributed photographs and/or space onboard their vessels for data collection. Furthermore, we thank the anonymous reviewers, who provided valuable input into the manuscript. Photographs used in the figures are copyright of University of Iceland (Figs. 2,3,4a1,b,c, 5 & 6a,b,d) Elding Adventures at Sea (Fig. 6c), and Charlie Frank Lavin (Elding Whale Watching Akureyri) (Fig. 4a2).

Publisher's version (útgefin grein), [No abstract available], First, we would like to thank Thierry Jauniaux from the University of Liège for collecting samples from Ha01 andguiding all sample collection. We are also grateful to the other interns and students from Húsavík Research Centerwho collected data and helped to coordinate this stranding response, and specifically to Nolwenn Dameron andChiara Vischioni for taking photographs of dead whales. More generally, thank you to the guides, locals, and touristswho reported sightings all around Iceland. In addition, we are grateful to Gísli Víkingsson from the Icelandic MarineResearch Institute and Paul Wensveen at University of Iceland for providing information on Icelandic beaked whalesightings and strandings. Thank you to Andrew Brownlow for his advice on publishing this report and personal com-munication of beaked whale stranding information. Finally, we would like to thank the editor, associate editor, andtwo anonymous reviewers for providing constructive feedback and improving the quality of this article.

Publisher's version (útgefin grein), Non-breeding movement strategies of migratory birds may be expected to be flexibly adjusted to the distribution and quality of habitat, but few studies compare movement strategies among populations using distinct migration routes and wintering areas. In our study, individual movement strategies of red-necked phalaropes (Phalaropus lobatus), a long-distance migratory wader which uses saline waters in the non-breeding period, were studied using light-level geolocators. Results revealed a migratory divide between two populations with distinct migration routes and wintering areas: one breeding in the north-eastern North Atlantic and migrating ca. 10,000 km oversea to the tropical eastern Pacific Ocean, and the other breeding in Fennoscandia and Russia migrating ca. 6,000 km-largely over land-to the Arabian Sea (Indian Ocean). In line with our expectations, the transoceanic migration between the North Atlantic and the Pacific was associated with proportionately longer wings, a more even spread of stopovers in autumn and a higher migration speed in spring compared to the migration between Fennoscandian-Russian breeding grounds and the Arabian Sea. In the wintering period, birds wintering in the Pacific were stationary in roughly a single area, whereas individuals wintering in the Arabian Sea moved extensively between different areas, reflecting differences in spatio-temporal variation in primary productivity between the two wintering areas. Our study is unique in showing how habitat distribution shapes movement strategies over the entire non-breeding period within a species., RvB was funded by the Netherlands Organization for Scientific Research (project number 866.13.005) and supported by the LUVRE project. We also thank the European Union (FP7-PEOPLE-2013-CIG, 618841) for funding our research. BM and SH were supported by Fram Center and RR was supported by a postdoctoral contract of the Juan de la Cierva program, from the Spanish Ministerio de Ciencia e Innovación (JCI-2012-11848, CGL2013-42585-P, CGL2016-78530-R). Work at Constable Pynt by OG and LB (part of program 1,036 Interactions) were supported by the French Polar Institute, IPEV. Work at Fetlar was funded by the RSPB and the Shetland Ringing Group. AL received financial support from the Academy of Finland (grant 275606). AS was supported through the grant of RFBR #18-05-60261 Arctic, JAA from FCT (SFRH/BPD/91527/2012) and BÞ from RANNIS (152470-052) and University of Iceland equipment fund. KV received support from Kone foundation.

Publisher's version (útgefin grein), Baleen whales face the challenge of finding patchily distributed food in the open ocean. Their relatively well-developed olfactory structures suggest that they could identify the specific odours given off by planktonic prey such as krill aggregations. Like other marine predators, they may also detect dimethyl sulfide (DMS), a chemical released in areas of high marine productivity. However, dedicated behavioural studies still have to be conducted in baleen whales in order to confirm the involvement of chemoreception in their feeding ecology. We implemented 56 behavioural response experiments in humpback whales using two food-related chemical stimuli, krill extract and DMS, as well as their respective controls (orange clay and vegetable oil) in their breeding (Madagascar) and feeding grounds (Iceland and Antarctic Peninsula). The whales approached the stimulus area and stayed longer in the trial zone during krill extract trials compared to control trials, suggesting that they were attracted to the chemical source and spent time exploring its surroundings, probably in search of prey. This response was observed in Iceland, and to a lesser extend in Madagascar, but not in Antarctica. Surface behaviours indicative of sensory exploration, such as diving under the stimulus area and stopping navigation, were also observed more often during krill extract trials than during control trials. Exposure to DMS did not elicit such exploration behaviours in any of the study areas. However, acoustic analyses suggest that DMS and krill extract both modified the whales’ acoustic activity in Madagascar. Altogether, these results provide the first behavioural evidence that baleen whales actually perceive prey-derived chemical cues over distances of several hundred metres. Chemoreception, especially olfaction, could thus be used for locating prey aggregations and for navigation at sea, as it has been shown in other marine predators including seabirds., This research was funded by the Fondation Total (www.fondation.total.com), grant #144903 to A.C., and the Ministère de l'Enseignement Supérieur et de la Recherche (www.enseignementsup-recherche.gouv.fr) to B.B., Bourse doctorale. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

Publisher's version (útgefin grein), Genomes are dynamic biological units, with processes of gene duplication and loss triggering evolutionary novelty. The mammalian skin provides a remarkable case study on the occurrence of adaptive morphological innovations. Skin sebaceous glands (SGs), for instance, emerged in the ancestor of mammals serving pivotal roles, such as lubrication, waterproofing, immunity, and thermoregulation, through the secretion of sebum, a complex mixture of various neutral lipids such as triacylglycerol, free fatty acids, wax esters, cholesterol, and squalene. Remarkably, SGs are absent in a few mammalian lineages, including the iconic Cetacea. We investigated the evolution of the key molecular components responsible for skin sebum production: Dgat2l6, Awat1, Awat2, Elovl3, Mogat3, and Fabp9. We show that all analyzed genes have been rendered nonfunctional in Cetacea species (toothed and baleen whales). Transcriptomic analysis, including a novel skin transcriptome from blue whale, supports gene inactivation. The conserved mutational pattern found in most analyzed genes, indicates that pseudogenization events took place prior to the diversification of modern Cetacea lineages. Genome and skin transcriptome analysis of the common hippopotamus highlighted the convergent loss of a subset of sebum-producing genes, notably Awat1 and Mogat3. Partial loss profiles were also detected in non-Cetacea aquatic mammals, such as the Florida manatee, and in terrestrial mammals displaying specialized skin phenotypes such as the African elephant, white rhinoceros and pig. Our findings reveal a unique landscape of “gene vestiges” in the Cetacea sebum-producing compartment, with limited gene loss observed in other mammalian lineages: suggestive of specific adaptations or specializations of skin lipids., This work was supported by Project No. 031342 cofinanced by COMPETE 2020, Portugal 2020 and the European Union through the ERDF, and by Fundac¸a~o para a Cie^ncia e a Tecnologia through national funds. R.R.F. thanks the Danish National Research Foundation for its support of the Center for Macroecology, Evolution, and Climate (grant DNRF96). We acknowledge the various Cetacea genome consortiums for genome sequencing and assemblies. We also thank Gısli Vikingsson at the Marine and Freshwater Research Institute in Iceland for lending us the Larsen gun and to North Sailing whale watching for the use of their zodiac.

Publisher's version (útgefin grein), Central place foraging theory (CPF) has been used to predict the optimal patch residence time for air-breathing marine predators in response to patch quality. Humpback whales (Megaptera novaeangliae) forage on densely aggregated prey, which may induce drastic change in prey density in a single feeding event. Thus, the decision whether to leave or stay after each feeding event in a single dive in response to this drastic change, should have a significant effect on prey exploitation efficiency. However, whether humpback whales show adaptive behavior in response to the diminishing prey density in a single dive has been technically difficult to test. Here, we studied the foraging behavior of humpback whales in response to change in prey density in a single dive and calculated the efficiency of each foraging dive using a model based on CPF approach. Using animal-borne accelerometers and video loggers attached to whales, foraging behavior and change in relative prey density in front of the whales were successfully quantified. Results showed diminishing rate of energy intake in consecutive feeding events, and humpback whales efficiently fed by bringing the rate of energy intake close to maximum in a single dive cycle. This video-based method also enabled us to detect the presence of other animals around the tagged whales, showing an interesting trend in behavioral changes where feeding duration was shorter when other animals were present. Our results have introduced a new potential to quantitatively investigate the effect of other animals on free-ranging top predators in the context of optimal foraging theory.

Publisher´s version (útgefin grein), Humpback whale songs associated with breeding behaviors are increasingly reported outside of traditional low latitude breeding grounds. Songs from a subarctic feeding ground during the winter were quantitatively characterized to investigate the structure and temporal changes of the songs at such an atypical location. Recordings were collected from 26. January to 12. March, 2011, using bottom mounted recorders. Humpback songs were detected on 91% of the recording days with peak singing activities during 9.–26. February. The majority of the recordings included multiple chorusing singers. The songs were characterized by a) common static themes which transitioned consistently to predictable themes, b) shifting themes which occurred less predictably and c) rare themes. A set median sequence was found for four different periods (sets) of recordings (approximately 1 week each). The set medians were highly similar and formed a single cluster indicating that the sequences of themes sung in this area belonged to a single cluster of songs despite of the variation caused by the shifting themes. These subarctic winter songs could, thus, represent a characteristic song type for this area which is comparable to extensively studied songs from traditional low latitude breeding grounds. An increase in the number of themes per sequence was observed throughout the recording period including minor changes in the application of themes in the songs; indicating a gradual song progression. The results confirm that continual singing of sophisticated songs occur during the breeding season in the subarctic. In addition to being a well-established summer feeding ground the study area appears to be an important overwintering site for humpback whales delaying or canceling their migration where males engage in active sexual displays, i.e. singing. Importantly, such singing activity on a shared feeding ground likely aids the cultural transmission of songs in the North Atlantic., This research was funded by the Doctoral Grants of The University of Iceland Research Fund (in Icelandic), 200913-Doktorsstyrkir Rannsóknasjóðs Háskóla Íslands to EEM; http://sjodir.hi.is/sites/sjodir.hi.is/files/rsj_pdf_uthl2009.pdf. Further information about the grant can be found at the funder’s website: http://sjodir.hi.is/research_funds_0. The second funder is The Conservation Fund of Pálmi Jónasson, and a list of grant receivers can be found at the following webpage: http://www.natturuverndarsjodur.is/subpage2_2.asp. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

Publisher's version (útgefin grein), Killer whales have a cosmopolitan distribution and as a species are generalists, feeding on a variety of prey. However, local populations tend to specialise on specific prey types. In Icelandic waters, killer whales are generally associated with herring and, thus, have been presumed to be herring specialists. However, recent studies suggest a more complex foraging ecology, possibly including a mosaic of strategies. With increased observational effort in recent years due to research and whale-watching activities, there have been several reports of interactions with different prey, including confirmed predation events. In this study we aimed to summarise the range of potential prey of killer whales observed in Icelandic waters. We report on 12 previously unpublished accounts and review 15 accounts published in the scientific literature or local newspapers, making a total of 27 events where killer whales were observed interacting with actual or potential prey. Thirteen different species, including birds (n = 1), cephalopods (n = 1), fish (n = 5) and marine mammals (n = 6), are reported, although herring is by far the species that killer whales are most often observed interacting with. This study provides the first summary of actual and suspected killer whale prey in Icelandic waters, and contributes towards our understanding of this population’s prey preferences. However, describing the diet of individuals/groups was not possible and this study points to a need for continued monitoring to understand the intricacies of killer whale foraging behaviour in this area., MB was employed by Elding Whale Watching, MOE was employed by Whales Hauganes ehf., MTM was employed by Láki Tours, JNR was employed by Special Tours and BT was employed by Iceland Pro Cruises. The funders provided support in the form of salaries for authors and in all cases (except Iceland Pro Cruises) provided platforms from where observations were made, but did not have any additional role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript. The specific roles of these authors are articulated in the ‘author contributions’ section. Funding for dedicated research was provided by the Icelandic Research Fund. The funder had no role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript.