L'environnement marin est soumis à un ensemble de processus physiques, chimiques et biologiques qui le rendent très dynamique. Les prédateurs tels que les oiseaux marins doivent donc ajuster leurs mouvements aux changements de disponibilité de leurs proies afin de survivre et de se reproduire. L'évolution de leur plasticité comportementale se traduit par la mise en place d'un éventail de tactiques de prédation. Nous avons étudié les comportements de recherche alimentaire chez le fou de Bassan Morus bassanus en Atlantique nord afin d'évaluer l'ampleur de leur plasticité comportementale au cours de leurs mouvements en mer. Ces analyses basées sur les enregistrements d'appareils électroniques miniaturisés portés par les oiseaux (GPS et géolocateurs) ont été effectuées à cinq échelles spatio-temporelles : individuelle, populationnelle, meta-populationnelle, saisonnière et interannuelle. La plasticité individuelle est forte et se traduit, principalement par le biais d'une modulation de la durée des voyages en mer et des zones d'alimentation exploitées. Ceci sous-entend une mémorisation de la position des zones de nourrissage les plus profitables et de leur variabilité spatio-temporelle ; postulat confirmé par nos analyses qui indiquent que les fous anticipent la position de leur aire de nourrissage dans les premiers kilomètres de leur voyage en mer, alors que celle-ci n'est pas encore en vue. Nous avons également identifié des différences inter-populationnelles notoires pour les mouvements en mer et pour les domaines vitaux des fous pendant la saison de reproduction, mais aussi pendant la période hivernale. A l'automne et au printemps, nos analyses nous ont en outre permis d'identifier un corridor migratoire emprunté par les fous entre les Shetland et l'Afrique de l'Ouest, alors qu'on considère généralement que cette espèce présente une dispersion non-orientée en dehors de la saison de reproduction. L'ensemble de nos résultats ont des implications majeures pour une meilleure compréhension de l'écologie spatiale des prédateurs marins confrontés à la variabilité naturelle et anthropique de leur environnement, ainsi que pour la gestion de leurs populations et la mise en place d'aires marines protégées ou de mesures conservatoires ajustées aux dynamiques spatio-temporelles. / Physical, chemical and biological processes generate considerable variability in the distribution and abundance of marine organisms. In order to survive and successfully breed, marine predators, among them seabirds, must adjust their movements to changes in the availability of their prey. We studied the foraging behaviour of the northern gannet Morus bassanus in several European colonies to understand how a flexible predator manages environmental variability. We analysed records from miniaturized data loggers (GPS and geolocators) at five spatio-temporal scales: individual, populational, meta-populational, seasonal and inter-annual. These data revealed strong individual plasticity, which allows gannets to modulate the length and duration of their foraging trips and to exploit a panel of memorized feeding areas, for which they anticipate location from a distance. We identified differences in the movements at sea and in home range between colonies during the breeding and the interbreeding seasons. Although gannets were thought to follow a non-oriented dispersion during the interbreeding season; our results showed a clear migratory corridor from Shetland to the West African coast. These results have major implications for a better comprehension of spatial ecology of marine predators facing natural and anthropogenic variability of their environment, as well as for population management, the implementation of marine protected areas, and any conservation measures which depend on spatio-temporal dynamics.

Following catastrophic exploitation throughout the North Atlantic, breeding seabird populations have begun to recover thanks to regulatory protection and restoration and management efforts. As bird populations increase, new challenges emerge, including overgrowth of vegetation that limits the open nesting habitat favored by most tern species. Though managers have used a variety of measures to reduce vegetation cover, these techniques have rarely been quantified or compared experimentally. During the summers of 2009 and 2010, I applied two different techniques, controlled burning and artificial weed barriers (muslin fabric and artificial turf) to experimental plots on Eastern Egg Rock and Outer Green Island, near-shore seabird nesting islands in mid-coastal Maine. I then monitored vegetation regrowth and use by nesting terns to assess the effectiveness of these techniques for opening and maintaining Common Tern nesting habitat during a full breeding season, comparing treated plots to vegetated control plots and existing tern nesting habitat. Burned areas did not remain open for the full nesting season, but regrew shortly after laying, leading to near-complete nest failure in these plots. Tern nest and fledging success was similar in weed barrier (1.37 chicks/pair) and untreated tern nesting habitat (1.38 chicks/pair) plots. Replacement of existing vegetation, tested at a limited scale on Outer Green Island, did not succeed. These three techniques represent only a small fraction of vegetation management techniques used throughout the North Atlantic region. Through literature review and consultation with North Atlantic colony managers, I collected information on vegetation management on 34 tern nesting islands between 33 and 55° N latitude and developed a summary of different vegetation control techniques used. I identified 14 technique types suitable for use in nesting colonies: i.e., that can be applied before and after (but not during) the nesting period of May-July, that do not cause destructive impacts to the surrounding ecosystem, and that involve materials and labor that can be transported to inaccessible offshore islands. Of these techniques, 8 created usable tern nesting habitat for a full breeding season, and the most successful techniques required constructing habitat over existing vegetation. The success of different methods depended heavily on the plant communities and soil types involved. In general, vegetation management options were more limited and less successful for elevated, rocky islands than for low, sandy islands. Often, techniques that successfully removed one species or group of species (i.e., perennial grasses) failed due to rapid colonization by other species (i.e., herbaceous annuals). This review of past and ongoing vegetation management techniques used on seabird nesting islands, including their costs, methods for application, and effectiveness, provides seabird managers a reference when evaluating current and future vegetation management programs.

This dissertation aims to contribute toward the understanding of water-entry and -exit behaviors in nature. Since water is nearly a thousand times denser than air, transitioning between the two mediums is often associated with significant changes in force. Three topics with implications in water-entry are discussed, along with a fourth topic on water-exit. For a plunge-diving seabird, the first two stages of water-entry (initial impact and air-cavity formation) create large stresses on the bird's neck. Linear stability analysis of a cone-beam system impacting water shows buckling and non-buckling behaviors on the beam, which is extended to the diving birds. The next topic is related to the third stage of water-entry (air-cavity pinch-off), in which the chest feathers come in contact with the water. Here, the elasticity of Northern Gannet contour feathers is calculated using the nonlinear bending equation. The third topic will explore the formation of ripples along air cavity walls and their resulting force after pinch-off. An acoustic model predicts the observed wavelengths of the ripples. The final topic will delve into the mechanics of how animals leap out of water. A scaling law that balances the power of thrust and drag will predict the height of the jump. Finally, a bio-inspired robot was built to help identify physical conditions required to jump out of water. / Ph. D. / In nature, animals use enter and exit water (water-entry and water-exit, respectively) as a strategy for hunting prey and/or escaping predators. In this dissertation, we focus on the fluid mechanics of water-entry and water-exit phenomena as it pertains to animals. First, we study how seabirds plunge-dive into water at high speeds without neck injuries. Second, we discuss calculating the elasticity of bird feathers. Next, the rippling behavior of air-cavities is studied in the context of force production. Finally, we study the water-exit phenomenon of animals leaping out of water. The topics of this dissertation have implications in the water-entry and -exit of vehicles and autonomous robotics.

En milieu marin, les oiseaux sont souvent observés en groupe lors de la recherche et de la chasse de proies. Les mécanismes sous-jacents à ces comportements ainsi que leurs conséquences sur l'approvisionnement alimentaire des individus sont peu connus du fait des difficultés d'observation en mer. Pour expliquer ces stratégies de groupe communes à de nombreuses espèces d'oiseaux marins, la principale hypothèse propose qu'elles répondent aux spécificités de leurs champs de proies. Le milieu marin pélagique est caractérisé par une forte variabilité spatio-temporelle. Dans ce milieu ouvert, les ressources sont agrégées de façon hiérarchiques et leur localisation est changeante. Le milieu marin est ainsi propice au développement de stratégies de groupe pour l'approvisionnement alimentaire. Cette thèse étudie les interactions sociales lors des voyages en mer d'un oiseau marin, le fou du Cap. L'objectif est d'en évaluer la prévalence et les effets sur l'approvisionnement alimentaire des individus. Des adultes reproducteurs ont été équipés de GPS et de micro-caméras afin d'étudier leurs mouvements en mer en relation avec leur contexte proximal. Tous les oiseaux équipés ont interagi avec des congénères, lors des phases de posées sur l'eau, en vol pour la recherche de proie, ou en chasse sur un banc de proies. La présence de congénères est le moteur principal des mouvements des fous du Cap à une échelle inférieure à la dizaine ou la vingtaine de kilomètres. Plusieurs types d'interactions ayant une influence sur les capacités d'approvisionnement alimentaire des individus ont été mis en évidence. Lors de la recherche de proies, les fous réagissent à leurs congénères en modifiant leur direction de vol, et réduisent ainsi leur temps de recherche. Les fous sont attirés par les agrégations de congénères ; la détection de groupes de prédateurs en chasse augmente les distances de détection des proies. Par ailleurs, des observations vidéos sous-marines de groupes de prédateurs en chasse sur des bancs de poissons ont été utilisées pour quantifier l'influence des prédateurs sur les captures de proies des fous du Cap. Les attaques successives des prédateurs déstructurent les bancs et augmentent les succès de capture des individus. La thèse met en évidence le rôle prépondérant des interactions sociales entre oiseaux marins au cours de toutes les étapes d'un voyage d'approvisionnement alimentaire : de l'orientation vers une zone potentielle de nourrissage à la capture de proies, en passant par la localisation et l'exploitation de bancs de poissons. Le développement des stratégies de groupe chez les fous du Cap répond d'une part à la difficulté de localisation et d'autre part aux stratégies d'évitement de leurs proies. La capacité à former des groupes de chasse pour rechercher et exploiter des proies pourrait constituer une condition essentielle au maintien des populations de fous du Cap, et pourrait expliquer la forte occurrence de ce comportement chez les oiseaux marins. La notion de compétition entre oiseaux de mer serait donc à tempérer, tant la facilitation entre eux est importante. / In the marine environment, seabirds are commonly observed foraging in groups. The mechanisms underlying these behaviours, and their consequences on the foraging success of individuals, are poorly understood due to the difficulties in studying their behaviour at sea. The main hypothesis proposed to explain these group strategies, which are common to many seabird species, is that seabirds respond to the characteristics of their prey fields. The marine environment is vast and highly dynamic. The resources are aggregated in hierarchical patches of which the location is constantly changing. The marine environment therefore favours the evolution of foraging group strategies to increase the success of individuals. The objective of this thesis is to study the social interactions during the foraging trips of a seabird, the Cape gannet, and to study their effects on the foraging decisions of individuals. Breeders were equipped with GPS devices and video-cameras in order to study their movement at sea in relation to their proximate environment. All the individuals equipped in this study interacted with conspecifics at sea, either when sitting on the water, flying in search for prey, or hunting at a school of fish. Predators within the proximate environment of Cape gannets were the main drivers of their movement patterns at scales roughly < 20 km. Several types of interactions were observed to affect the foraging capacities of individuals. While searching for prey, gannets reacted to conspecifics by changing their flight direction thereby reducing the time to find prey. Gannets were attracted to aggregations of conspecifics, and the detection and joining of foraging groups increased their abilities to find and hunt for inconspicuous prey. Furthermore, underwater video footages of pelagic fish schools under predation were used to quantify the influence of group foraging on the feeding success of Cape gannets. Successive attacks by several individuals disorganized the fish schools and increased the feeding success of individual birds. This thesis highlights the important role of social interactions along all stages of a foraging trip in Cape gannets: when choosing a direction from the colony to orientate towards a patch of food, in order to locate inconspicuous prey, and to capture fish in schools. The use of group strategies in Cape gannets seems to have evolved in response to both the difficulties in locating prey in the marine environment and the anti-predatory behaviour of fish schools. The ability to form groups to forage at sea could be essential to the persistence of Cape gannet populations. These mechanisms could partly explain the prevalence of colonial breeding in seabirds. Competition between seabirds should therefore be moderated, as facilitation during foraging seems to play a crucial role in enhancing feeding success of individuals.

L’Arctique se réchauffe deux fois plus vite que le reste du monde, entrainant des changements majeurs des écosystèmes marins. Par exemple, l’étendue de la banquise diminue, et la distribution des masses d’air change, modifiant les régimes de vents et de précipitations. Parallèlement à ces changements climatiques, l’Arctique est soumise à une pollution anthropique croissante amenée par les circulations atmosphériques et océaniques, et accentuée par le développement des activités humaines locales. Dans ce contexte, il est urgent de comprendre les impacts écologiques de ces modifications environnementales sur les espèces de cette région. Les mergules nains (Alle alle) sont les oiseaux marins les plus abondants de l’Arctique, et des acteurs clés des réseaux trophiques côtiers. Bien que des travaux récents aient suggéré une forte résilience de ces organismes aux changements globaux, une étude approfondie permettant de comprendre de manière détaillée l’impact de ces changements était essentielle. Au cours de ce travail de thèse, nous avons donc utilisé une approche pluridisciplinaire (écologie alimentaire, écotoxicologie, bioénergétique, écologie du déplacement) menée à long terme afin de caractériser la sensibilité des mergules nains aux changements de leur environnement pendant la saison de reproduction (été) et en hiver. Nous avons pour cela étudié une population de mergules nains au Groenland Est. Nos résultats montrent que les mergules sont fortement impactés par les changements en cours. Pendant la période de reproduction, leurs proies changent et leur effort de plongée augmente en l’absence de banquise, même s’ils demeurent fidèles à leur zone de nourrissage sur le talus continental. Ceci tend à diminuer leur condition corporelle et celle de leur poussin, mais n’impacte pas leur survie. En hiver, les mergules nains optimisent leur migration et leur distribution en fonction de la distribution de leurs proies et de leur paysage énergétique. Ainsi, nos modèles prédictifs indiquent qu’un réchauffement de l’Atlantique nord pourrait être bénéfique pour les populations en diminuant leurs besoins énergétiques. Enfin, nous avons trouvé que les mergules nains consomment des microplastiques, et ce en les confondant avec leurs proies. Cette source de pollution supplémentaire pourrait augmenter avec la fonte de la banquise qui libère des microplastiques jusque-là stockés dans la glace. Ce travail souligne l’importance des programmes à long terme pour l’étude des impacts des changements globaux. / The Arctic is warming twice faster than the rest of the world, leading to major changes for marine ecosystems. For example, sea-ice extent is decreasing, and air mass distribution is changing, thus modifying wind and precipitation regimes. In parallel, the Arctic is subject to increasing anthropogenic pollution carried by atmospheric and oceanic circulation, and accentuated by the development of local human activities. In this context, there is an urgent need to understand the ecological impacts of these environmental modifications on the species of this region. Little auks (Alle alle) are the most abundant seabird in the Arctic, and key players of coastal food webs. Although recent works suggested a high resiliency of little auks to global changes, a comprehensive study was needed to understand in detail the impacts of these changes. Through this work, we used a multidisciplinary approach (diet ecology, ecotoxicology, bioenergetics, foraging ecology) on the long term to characterize little auk sensitivity to environmental changes during the breeding season (summer) and in winter. We therefore studied a little auk population in East Greenland. Our results show that little auks are indeed impacted by ongoing changes. During the breeding season, their prey change and their diving effort increase when there is no sea-ice, even if they remain faithful to their feeding grounds on the continental slope. This tends to decrease their body condition and that of their chick, but does not impact their survival. In winter, little auks optimize their migration and their distribution according to the distribution of their prey and their energetic landscape. Therefore, our predictive models indicate that a warming of the North Atlantic could be benefic for little auk populations, by reducing their energetic needs. Finally, we found that little auks ingest microplastics, by confusing them with their prey. This additional source of pollution could increase with sea-ice loss that release microplastics stocked in the ice. This work underlines the importance of long term monitoring programs for the study of global change impacts.

Seabirds are often used as indicator species for changes in marine ecosystems due to the species visibility and sensitivity to changing conditions, such as changes in prey abundance. They often reside in habitats affected by anthropogenic impacts such as large-scale fisheries and pollution. Understanding the connection between seabirds and their surrounding environment can give us important insight about the ecology of the ocean and how anthropogenic pressures affects it. Studying feeding habits, and foraging behavior especially, is useful for understanding seabird´s responses to changing environments. Feeding studies are commonly used in seabird monitoring and requires a lot of time and resources. Monitoring of seabirds are also logistically challenging, and the risk of disturbing bird colonies must be considered. It can be especially complicated when studying cliff nesting seabirds such as the common murre, Uria aalge, the study species for this thesis. Photography as a method for monitoring seabirds may limit the need of people on site, hence minimize disturbance and save time and resources. This study provides insight in whether it is a viable option to use photography instead of on-site field studies when monitoring sea birds. This was accomplished by installing cameras and monitor a feeding study at Stora Karlsö, Sweden, parallel with performing the usual monitoring in the field. This thesis makes it clear that a camera study very well could replace the field study without any larger concerns, although, improvements need to be considered if the study is to maintain a high quality and for results to be reliable.

During 2008 – 2009, we quantified foraging behavior of adult Atlantic puffins (Fratercula arctica) by deploying time-depth recorders (TDRs) on 18 adults and collected morphological measurements from 40 adults nesting on Petit Manan Island, Maine. Dive data were successfully retrieved from 5 birds foraging for 14 days in 2008, and 8 birds foraging for 18 days in 2009. Pooling across all birds, a total of 8,097 dives were recorded, with peaks in activity during 0400-0800 and 1600-2000, and no diving between 2100 and 0400. Mean (± SD) dives/bird/day was 276.4 (± 84.7), with dives grouped into bouts lasting 17.8 (± 31.5) minutes, consisting of 8.9 (± 3.4) dives. Dive depth was less than 15 m for 86% of the dives. Mean maximum dive depth across birds was 9.7 (± 1.7) m, with the deepest dive being 40.7 m. Females made fewer deep dives (27-41 m), had more midday dives (1000 - 1559), and their dives were spread across a greater number of bouts per day than males. Given a mean foraging trip length of 60.1 (± 38.3) minutes for 26 birds observed in 2009, we estimate that adult puffins foraged, on average, within 31 km of the colony. Morphological measures were recorded by a single observer and included body mass, wing chord, bill depth, bill length, culmen, and head-bill length, and represented 19 males and 21 females, based on blood sample analysis. Data were analyzed using classification trees, and our final tree used culmen length and bill depth to correctly classify 34 of 40 (85%) birds (kappa = 0.695, P < 0.01). Use of our model can greatly improve the ability of biologists to identify sex of puffins in the field at this colony site, but variability in morphological data we collected at addition colonies indicates that future work is needed to determine its applicability throughout the Gulf of Maine. During 2009, we measured burrow characteristics of alcids and empty burrows. Breeding success and burrow characteristics were measured for nests of 104 puffins, 58 guillemots and 4 razorbills, with burrow characteristics measured for an additional 12 guillemot and 56 empty burrows. Mean diameter of burrow openings of puffins, guillemots, razorbills and empty burrows were significantly different, and artificial puffin burrows had significantly smaller openings than natural while artificial and natural guillemot burrows had similar opening diameters. Hatch, chick, and nest success of puffins was similar among burrow types, but guillemots had higher hatch and nest success in artificial burrows. The variables we used to create models for predicting hatch and nest success for puffins and guillemots had inadequate discriminatory power to predict success.

De nombreux espèces utilisent des signaux multicomposants/multimodales. Au cours de cette thèse, nous avons étudié les signaux acoustiques et visuels produits dans le cadre du choix du partenaire chez le Manchot royal. Concernant les composantes acoustiques, nous avons identifié des arrangements syllabiques spécifiques à chacun des sexes. La fréquence fondamentale et l'énergie des cris des manchots royaux, ainsi que certaines caractéristiques colorimétriques signalent des informations sur la classe d'âge de l'émetteur. Nous avons montré que l'appareil vocal des manchots royaux permet les individus de produire deux bandes de fréquences harmoniques puisqu'ils présentent un syrinx trachéo-bronchique et donc deux sources sonores. En résumé, ce travail de thèse a contribué à une meilleure compréhension des signaux utilisés dans le cadre du choix du partenaire chez une espèce monomorphique qui présente un comportement reproducteur très coûteux. / Communication signals used in sexual selection can be costly to produce and even reduce the emitter’s fitness. Many species use multicomponent signals communication systems in different signal modalities. Here, we study visual and acoustic signals produced in the context of mate choice on a sexually monomorphically ornamented seabird, the king penguin. We identified a sex-specific syllable pattern in the vocalisations of 1-year-old fledglings, juveniles and adult birds. We found that fundamental frequency and energy components of calls and beak spot and ear patch ornament parameters signal information about the age-class of the emitter. Investigating the vocal apparatus of adult king penguins, we showed that king penguins can produce “two voices” since they have a tracheobronchial syrinx, i.e. two sound sources. This thesis contributed to our understanding of signals used in mate choice in a sexually monomorphically ornamented species that exhibits a very costly breeding behaviour.

Most albatrosses are critically endangered, endangered or vulnerable due to the deleterious impact of fisheries, pollution, introduced species, habitat alteration, and climate change. Foraging behaviour influences many aspects of seabird biology, and a detailed understanding of foraging ecology is required to better predict the impacts of significant changes to the marine environment. Campbell Albatross (Thalassarche impavida) is a threatened endemic, confined to a small number of locations on Campbell Island, New Zealand and was recently split from the closely related Black-browed Albatross (T. melanophrys). We currently lack much basic information on the foraging behaviour of this species, hindering our ability to understand how change may have occurred in the past and make predictions about it’s long-term future. First, I used GPS loggers and stable isotope analysis of blood to investigate how distribution and foraging effort (distance travelled and duration) varied with sex and breeding stage. I found that Campbell Albatrosses are sexually dimorphic and showed sex-specific foraging behaviour and habitat use – although this varied by stage of reproduction. Because males and females may be vulnerable to different threats, such as interactions with fisheries, I compared the spatial overlap and high resolution spatio-temporal overlaps between fisheries vessels and albatrosses within New Zealand’s Exclusive Economic Zone (EEZ). Albatrosses utilised 32% of the EEZ, however they overlapped with fisheries vessels in only 0.20% of the area. Previous research has demonstrated that the influence of fisheries vessels goes beyond the immediate location of the boat itself. Campbell Albatross have low levels of spatio-temporal overlap with fisheries – with males overlapping more than females. More generally, my results indicate that adding data on fine scale interactions will improve fisheries risk assessments, and provide information needed for the conservation and management of the Campbell Albatross. A key development in recent ecological research has been a greater appreciation that inter-individual variation in foraging behaviour can have profound population-level consequences. Accordingly I tested for individual differences in foraging behaviour in Campbell Albatrosses. The majority of individuals demonstrated both annual and inter-annual individual consistency in foraging locations, and the degree of specialisation was influenced by both sex and year. Consistent terminal latitude and longitude of foraging trips indicated high foraging area fidelity with a degree of flexibility in the fine-scale location. During brooding, females used the Campbell Plateau and showed more consistent behaviours than males, which tended to forage in the Southern Ocean. This adds to a growing body of evidence of individual foraging specialisation among seabirds in general and albatrosses in particular and reveals marked inter-individual differences in vulnerability to threats. In light of the evidence of individual foraging specialisations in the Campbell albatross, I also preformed a literature review of individual foraging specialisations across all seabirds. I found studies examining foraging specialisation for 35 species, with 28 (80%) providing evidence of consistent inter-individual differences (i.e. specialisation). Current studies suggest that specialisation is influenced by environmental variability and resource predictability, however, with limited data in tropical regions, more studies are needed to test these links. In summary, my thesis has provided new information on Campbell Albatross foraging ecology. Sex specific variations in behaviour and habitat use may influence conservation and management strategies. I have been able to contextualise the consistent individual differences in foraging distribution described for this species in light of global patterns of individual foraging specialisation in seabirds and highlight future areas of research.

During the summer of 2008 and 2009, we studied the ecology of the Kittlitz’s Murrelet (Brachyramphus brevirostris), a small diving seabird and candidate for the U.S. Endangered Species List, in Prince William Sound (PWS), Alaska. At-sea survey data suggests that the population significantly increased from 2001 to 2009, however there is limited evidence of reproductive success. Habitat use models showed individuals were observed in shallower waters, closer to glaciers, the shoreline, and further from moraines than the available habitat during the daytime. Finer extent sampling from 2008 suggests temperature-depth profiles also influence Kittlitz’s Murrelet daytime habitat use. The associations between Kittlitz’s Murrelets and water column characteristics are likely an effect of prey availability. Stable isotope work in 2009 suggests birds were generalist foragers prior to the breeding season, becoming more specialized following the breeding season. This specialization may have been a response to strict foraging constraints during the flightless fall molt. Time budgets of radio-tagged individuals suggest birds may have been responding to ephemeral prey concentrations, and working near their maximum energetic limits. Remote monitoring of radio-tagged individuals showed birds left the glacial fjord system during the nighttime, possibly spending these hours near gillnet fishing areas, suggesting a new possible area of concern in evaluating potential threats to Kittlitz’s Murrelet populations.