Vigilance behavior can aid in the detection of predators and may also play a role in observation of conspecifics, in food acquisition, and in the prevention of kleptoparasitism. However, in most occasions, vigilance is most important as an antipredator function. Generally, factors that increase the risk of predation also increase the amount of vigilance. We examined whether the reintroduction of the large predator, the wolf, in Yellowstone National Park (YNP) would influence coyote vigilance and foraging ecology. From December 1997 to July 2000, we collected 1743 h of coyote activity budgets. Coyote home ranges occurred within wolf territories (termed high-use or nonbuffer zone areas) and also between them in buffer zones. In high wolf use areas as well as when wolves were present, coyotes fed on carcasses much more; however, they increased the amount of vigilance and decreased rest to prevent predation. Wolf kills may provide a quick source of food and be energetically advantageous to coyotes; however, costs include increased vigilance, decreased rest, and a higher predation risk. Vigilance and avoidance behavioral responses to the reintroduction of large predators may ultimately be more common outcomes than actual killing by competing carnivores of prey. Keystone carnivore reintroductions have a variety of cascading effects throughout the ecosystem and can be driven by both numeric responses (trophic cascades) and behavioral responses ("behavioral cascades"). Behavioral cascades resulting from increased vigilance or spatial changes may lead ultimately to numeric changes and trophic cascades.

Dans l’optique de la gestion de population du puffin d’Audubon de Martinique, cette thèse a permis d’établir un diagnostic démographique et d’apporter des connaissances indispensables sur l’écologie marine de cette espèce. La population a connu une croissance assez marquée les dernières années, correspondant à une période où les rats ont été exterminés et le suivi de la colonie réduit pour limiter le dérangement. Cependant, le principal facteur ayant expliqué cette augmentation de la population, a été une amélioration des conditions marines favorisant une disponibilité des proies plus importante, particulièrement hors reproduction. L’augmentation de la survie des adultes a été alors expliquée en grande partie par un effet positif des variations de température d’eau de surface de l’océan (SST) hors reproduction et un effet positif du débit de l’Amazone avec un décalage d’un an. En mer, on remarque que le puffin d’Audubon de Martinique a un comportement sédentaire avec une distribution très régionale limitée aux Petites Antilles et proche des côtes du nord de l’Amérique du Sud. Sa niche alimentaire est sous la forte influence d’apports fluviaux de l’Amazone et de l’Orénoque, milieux à faible salinité et à SST élevée. De plus, les zones d’alimentation de la population de Martinique diffèrent de celle de Bahamas et cela suggère une double problématique de gestion de la sous-espèce de la Caraïbe. Ces nouvelles connaissances permettront de mieux orienter les mesures de conservation mais soulignent également le besoin de clarifier la taxonomie de cette espèce à l’échelle de la Caraïbe, la dynamique de la population et d’évaluer plus précisément les menaces en mer. / In the context of management of Audubon’s shearwater population from Martinique, this thesis has established a demographic diagnosis and provided essential knowledge on the marine ecology of this species. The population has experienced a fairly marked growth in recent years, corresponding to a period where the rats were exterminated and monitoring of colony was limited to reduce the disturbance. However, the main factor that explained the increase in population was improved marine conditions favoring greater availability of prey, especially outside reproduction. The increase in adult survival was then explained in large part by a positive effect of changes in ocean surface water temperature (SST) out of reproduction and a positive effect of the flow of the Amazon with a lag one year. At sea, we notice that the puffin Audubon Martinique has sedentary behavior with very limited regional distribution and the Lesser Antilles near the northern coast of South America. Its food niche is under the strong influence of riverine inputs of the Amazon and Orinoco, low salinity and high SST environments. In addition, foraging areas of Audubon's Shearwater from Martinique differ from that of the Bahamas and this suggests a double subspecies of the Caribbean management problematic. This new knowledge will help guide conservation measures but also underline the need to clarify the taxonomy of this species throughout the Caribbean, the dynamics of the population and to more accurately assess its threats at sea.

Les stratégies alimentaires peuvent être définies comme la mise en place d'ensembles cohérents de réponses morphologiques, physiologiques, écologiques ou comportementales permettant d’optimiser le succès alimentaire d’une espèce. Le présent travail s'est proposé d'aller au-delà de la simple analyse taxonomique des régimes alimentaires en utilisant les caractéristiques des proies pour explorer certains aspects des stratégies alimentaires et de l’énergétique de la prédation chez les mammifères marins de l’atlantique nord-est. L'objectif majeur était de contribuer à une meilleure compréhension du "pourquoi une proie est une proie ?" La valeur énergétique des proies est apparue comme un élément central des stratégies de prédation. Il en résulte que des coûts d'existence importants chez les mammifères marins doivent être soutenus par une alimentation de qualité élevée et ne peuvent pas être satisfaits simplement par une plus grande quantité de proies de qualité moyenne ou faible. Les résultats obtenus lors de cette thèse ont ainsi permis de progresser de la description des régimes alimentaires vers la compréhension de certaines relations fonctionnelles entre proies et prédateurs. Ainsi, les traits descriptifs de la qualité des proies, comme la teneur en lipides et la valeur énergétique, et les traits descriptifs des coûts d’existence des mammifères marins, comme l’indice mitochondrial et la teneur en lipides des muscles, sont significativement corrélés. Enfin, ce travail souligne que pour comprendre l'écologie alimentaire d'un prédateur, il faut surtout bien connaitre les caractéristiques de ses proies. / Foraging strategies can be defined as the establishment of a consistent set of morphological, physiological, ecological and behavioural responses allowing the optimization of foraging success. Beyond the simple description of the diet, the present work attempted to explore some aspects of foraging strategies and of the energetic of predation among northeast Atlantic marine mammals. The main goal of the study was to contribute to a better understanding of "why a prey is a prey?" Prey energy density appeared to be a key point of predation strategies. Hence, marine mammal species with high existence costs would need high quality prey items, and cannot fulfil their energy requirement just by ingesting more prey items of low to medium quality. The results of this thesis permitted to progress from a taxonomic description of marine mammal diets to the identification of functional relationships between prey and predators. Hence, traits of prey quality such as lipid content or energy density, and traits of predator cost of existence such as muscle mitochondrial density or muscle lipid content, were significantly correlated. Finally, this work underlines that in order to understand the foraging ecology of a predator, its prey characteristics have to be known.

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.

Increased afforestation and protective legislation in the latter half of the 20th Century allowed the British pine marten Martes martes population to recover from near extinction. Although still largely confined to northern Scotland, the marten population is expanding its size and range by utlising coniferous plantation forests which have become increasingly available. However, little is known about the marten’s ecology in plantation forestry, and less about how they may adapt to changing silvicultural trends. This study investigated aspects of pine marten ecology within Morangie forest, a managed plantation in NE Scotland, with the ultimate aim of formulating management guidelines for modern plantation forests. During the course of the study 11 pine marten were radiotracked and their home ranges mapped to examine marten-habitat associations at several spatial scales. Compositional analysis of habitat based on dominant vegetation type showed that martens established their home ranges in areas dominated by mature forest, whilst showing relative avoidance for open heath moor and grazed pasture. Within home ranges, foraging martens utilised patches of graminoid vegetation, such as those typically associated with Microtus voles, in areas with little or no tree canopy cover. These findings provide unequivocal evidence that fine-scale patches of non-forested habitat provide crucial foraging resources for marten, and therefore ought to be provisioned for in forest management plans. To assist the implementation of these requirements in forest planning, a model was developed to predict the fine scale distribution of Microtus-rich foraging habitat for marten using GIS-based habitat variables that are routinely available to forest managers: topographic wetness index, stand tree height and stand basal area. Management recommendations of ways to improve wind-firm plantation forests as habitats for pine marten are provided. To augment the investigation of marten spatial ecology, the diet of martens was examined seasonally through the analysis of contents from c. 2450 scats, 86 % of which were genetically identified as being pine marten in origin. Marten diets displayed marked seasonality, but small mammals, berries and small birds were the principal foods consumed based on both frequency of occurrence and estimated weight of biomass ingested. Comparison of the relative composition of small mammal species in the diet with those available in the environment revealed that marten displayed an indisputable preference for Microtus voles. Such habits demonstrate that the niche of Scottish martens has diverged from those in mainland populations which predominantly prey upon Clethrionomys voles. A comparison of the marten’s winter diet with those found in studies at similar latitudes (58°N) demonstrated that the Scottish diet was more similar to diets at more southerly latitudes as they contained more fruit and fewer large mammals than typically boreal diets. Investigation of inter-annual variation of the marten’s spring diet from five successive years revealed that Microtus were consistently the most important prey species in the diet each year. Indirect evidence of the relative abundance of Microtus suggested that Microtus populations were non-cyclic. Findings are discussed with reference to the unique ecological circumstances confronting marten in the Scotland; typical of insular populations the UK has a depauperate native fauna in comparison with mainland Europe, in addition to this, mild climatic conditions, particularly over winter, and a historically fragmented landscape appear to have allowed the niche of the Scottish marten to diverge from that considered typical elsewhere in its range. The Scottish marten is dependent on both forested and open habitats, and is both a Microtus specialist and trophic generalist.

Understanding the ecology of an organism is fundamental for defining conservation and management priorities for wildlife and natural ecosystems. The most basic ecological framework identifies the key components of an organism's habitat, and the scale for measuring the quality of those features. How these core needs are expressed and vary in the surrounding ecosystem changes over time and space. In marine systems, the physical environment has few strict boundaries, and variations regularly occur on a scale from days to decades. The dynamic and patchy nature of marine habitat makes defining the ecological roles of an animal difficult, even where baseline data exists. In this study I analyze long term field records on the ecological interactions between foraging gray whales (Eschrichtius robustus), and their mysid prey (Family mysidae) in Clayoquot Sound, B.C. By looking at spatial and temporal shifts at both trophic levels, I measure foraging responses and requirements, and assess prey resource availability and resiliency in the marine environment at a series of scales. Appreciation for bottom-up and topdown trophic interactions provides the foundation for identifying natural variability in marine habitat, and a baseline for conservation measures that seek to use marine predators as a barometer of broader ecosystem health.

The North Pacific humpback whale (Megaptera novaeangliae) population has been increasing at an average annual rate of ~6% since the early 1990s. In northern Southeast Alaska alone, there are now more whales than estimated for the entire North Pacific several decades ago. An understanding of how this growing population is repopulating traditional foraging grounds will benefit from detailed investigations of their prey preferences and trends in whale abundance and distribution relative to those prey. This dissertation examines these issues from late May until early September 2008 in Frederick Sound and Stephens Passage, a Southeast Alaskan feeding area historically used by humpback whales. The foundation for the study is an analysis of the life histories and abundance patterns of euphausiids, the principal prey of humpbacks in the area, during late spring and summer. Four species, Thysanoessa raschii, T. longipes, T. spinifera, and Euphausia pacifica, were identified in plankton net samples collected at random locations throughout the study site (n = 49) and in locations where a strong scattering layer was observed on a 120 kHz echosounder (n = 48). Both sample types varied in euphausiid species composition. Abundance patterns of immature euphausiids coupled with observations of females carrying spermatophores indicated differences between species in spawning schedules. Thysanoessa spp. began spawning in early April with the spring phytoplankton bloom and continued until late June, whereas E. pacifica began spawning in early June and continued until late August. This protracted recruitment of immature euphausiids was geographically widespread throughout the summer in contrast to adults, which, although present all summer, were found primarily in slope and shallow (< 100 m) areas. To determine if humpback whales preferred one euphausiid species or life-stage over another, net sample and hydroacoustic data collected in the vicinity of whales were compared to similar data collected in random locations throughout the study site. This revealed that whales targeted dense aggregations of adult euphausiids, but did not discriminate between the various species, which was surprising because of presumed differences in the energy density linked to their different spawning schedules. Additionally, whales did not spend time in areas with concentrations of immature euphausiids, which were likely not large enough during the study period to be suitable prey. With this preference for adult euphausiids, the abundance and distribution patterns of humpbacks were examined in relation to prey availability. Whale abundance was lowest at the beginning of the study in late May at ca. 68 whales and peaked in late July at ca. 228 animals – approximately 12% of the region’s estimated abundance for the study year. This study did not detect a concomitant increase in the availability of adult euphausiids, which is unsurprising since immature euphausiids would not recruit into the adult population until after the end of the study, and post-spawning mortality and predation pressure is presumably high during this time. Instead, whales clustered increasingly around comparatively fewer prey as the summer progressed. These observations, combined with a plateau in whale abundance after July, suggest that their abundance in the area was limited by euphausiid availability. Estimates of whales using the study site during the summer have remained similar over several decades despite a dramatic increase in humpback numbers in Southeast Alaska and elsewhere in the North Pacific. The results from this study suggest that, although the study site remains important seasonally to some whales, it is not a significant source of prey responsible for regional population growth in general. More likely, it is part of a network of feeding areas that has influenced the population trend. Further insight into these and the other issues raised in this dissertation could come from several additional analyses. An extended sampling season that captures the recruitment of immature euphausiids into the adult population would reveal whether a given year's prey cohort represents an important resource to whales in that same year, which has potential implications for interpreting mid-late season whale abundance patterns. As well, a photo-identification study would be useful in characterizing whale residency patterns and determining whether the abundance trends reflect a relatively small subset of the regional population using the area for most of the season or a continuous flow of a larger portion of the population. Finally, similar analyses as those outlined here but conducted in other areas within the region would provide additional insight into the network’s capacity to support the recovering whale population. / Graduation date: 2012

Understanding the movement behavior and foraging strategies of individuals across multiple spatial and temporal scales is essential not only for understanding the biological requirements of individuals but also for linking individual strategies to population level effects. Glacial fjords scattered throughout south-central and southeastern Alaska host some of the largest seasonal aggregations of harbor seals (Phoca vitulina richardii) in the world, and an estimated 15% of the harbor seal population in Alaska is found seasonally at these glacial ice sites. Over the last two decades, the number of harbor seals has declined at two of the primary glacial fjords, in Aialik Bay in south-central Alaska and in Glacier Bay in southeastern Alaska, thus raising concerns regarding the viability of seal populations in glacial fjord environments. From 2004-2009, the foraging ecology, diving behavior, and migration patterns of harbor seals from Glacier Bay National Park, Alaska were examined in relation to prey availability and oceanographic features in Glacier Bay and the surrounding regions of southeastern Alaska. Time-depth recorders, very high frequency transmitters, and satellite-linked transmitters were used to quantify the vertical and horizontal movement patterns of harbor seals in the marine environment. Specifically, (1) I characterized the diving behavior, foraging areas, and foraging strategies of female harbor seals from terrestrial and glacial ice sites relative to prey availability during the breeding season (May-June) in Glacier Bay, (2) I quantified the intra-population variation in at-sea post-breeding season (September-April) distribution and movement patterns of female harbor seals in relation to oceanographic features, (3) I quantified the post-breeding season migration patterns of female harbor seals relative to the boundaries of the marine protected area of Glacier Bay National Park, and (4) I characterized the use of the continental shelf region of the eastern Gulf of Alaska by female harbor seals from Glacier Bay, both as a foraging area and as a migratory corridor in relation to oceanographic features. During the breeding season, there was a substantial degree of intra-population variation in the diving behavior and foraging areas of juvenile and adult female seals from glacial ice and terrestrial sites in Glacier Bay. The presence of multiple diving strategies suggests that differences in the relative density and depth of prey fields in glacial ice and terrestrial habitats in addition to seal age and reproductive status may influence diving and foraging behavior of harbor seals. During the post-breeding season, juvenile and adult female harbor seals ranged extensively beyond the boundaries of the marine protected area of Glacier Bay National Park, throughout the northern inshore waters of southeastern Alaska and the continental shelf region of the eastern Gulf of Alaska between Cross Sound and Prince William Sound, Alaska (up to 900 kilometers away). Seals exhibited a relatively high degree of intra-population variation in their at-sea post-breeding season distribution patterns that may be a function of extrinsic factors such as oceanographic characteristics, which can influence prey availability as well as intrinsic factors including previous experience with foraging areas and seal condition and age. Use of the continental shelf region of the eastern Gulf of Alaska by harbor seals as a foraging area may be due to enhanced biological productivity which may be associated with ephemeral hydrographic and/or static bathymetric features. Despite extensive migrations of seals from Glacier Bay during the post-breeding season, there was a high degree of inter-annual site fidelity of seals to Glacier Bay the following breeding season after seals were captured. / Graduation date: 2012