Archaeological research has provided evidence of change in the settlement and subsistence practices of human groups inhabiting the Great Plains throughout the Holocene. A substantial part of this reorganization appears to be tied to concurrent changes affecting local bison populations, a species upon which these groups were uniquely dependant. Although bison are thought to have been strongly affected by the severe climates of the Mid-Holocene, there is an absence of appropriate models from which to interpret data in the archaeological and paleontological records. Nevertheless, new techniques are allowing for the determination of ecological information directly from prehistoric remains. This study uses stable isotope ratios (813C, 8'SN, 8D) in bone collagen to examine the dietary ecology of bison in Southern Saskatchewan during eight distinct time periods spanning the last 9,000 years. Stable isotopes of hydrogen and nitrogen in the tissues of animals relate to aspects of local climate, while stable-carbon isotope values reflect dietary choices. When employed in a comparative fashion, these sources may be used to construct simple models of foraging behaviour.<p> The environmental data developed from this investigation appear to correlate generally with patterns predicted by conventional models of Holocene climate. Nevertheless, at least one period of unexpectedly moderate temperature was identified from a context dating to the and Mid-Holocene. The ecological impact of such an episode may have been significant. In addition, the results of this study suggest that bison diet has a complex relationship with local climate. Changes in plant distribution resulting from variations of temperature and precipitation appear to have less of an impact upon bison consumption patterns than do climatically induced changes in the nutritional quality of vegetation. Nevertheless, during specific time periods characterized by similar climatic regimes, their relative consumption of certain forage species (C3 and C4 plants) does not appear to have been consistent. Such a discrepancy may reflect adaptive differences between bison from distinct time periods, or alternatively, the effects of a climatic difference undetectable by isotopic means. In either case, it would appear that bison of the past may have been subject to significant nutritional stresses that could have caused them to behave in fundamentally different ways from modern populations.

Albatross populations are currently in decline around the world. Survival and reproduction of these large pelagic birds depends mostly on the conditions they encounter in their marine environment. Their ability to range far across ocean basins exposes them to a variety of anthropogenic threats. It is thus crucial to understand spatial and temporal patterns in the distribution and habitat use of each albatross species during different stages of their annual cycle in the context of seasonally changing demands as well as environmental constraints, in order to develop effective conservation measures. Using Global Location Sensing (GLS) loggers I investigated the non-breeding movements and habitat associations of three threatened or near-threatened albatross species breeding in New Zealand’s Chatham Islands, the Chatham Albatross (Thalassarche eremita), Northern Buller’s Albatross (T. bulleri platei) and Northern Royal Albatross (Diomedea epomophora sanfordi), within South American waters. Chatham and Northern Buller’s Albatrosses mainly occupied waters with mean sea surface temperatures (SST) of 17-18ºC along the coasts of Chile and Peru, while Northern Royal Albatrosses were mostly found in 10-12ºC waters off southern Chile and Argentina. Monthly movement patterns were linked to seasonal shifts in temperature range, suggesting SST was an important environmental factor in explaining the observed spatial and temporal patterns. GLS loggers were also applied to study the patterns of movement and habitat use of Chatham Albatrosses when migrating across the South Pacific between breeding and non-breeding grounds. The route and timing of migration were consistent over the three year period of the study, although subject to individual variation. Stopovers on migration were found to be common, lasting between 3 and 26 days. Activity patterns suggested that birds stopped in order to forage en route. Lastly, I used high resolution Global Positioning Sensing (GPS) loggers to address the fine-scale movements and habitat selection of foraging Chatham Albatrosses over three years during early chick rearing. This is a time when their behaviour is expected to respond to increased energetic demands as they are feeding young chicks. Foraging trips lasted between 1 and 6 days and the foraging range rarely exceeded 400 km. The location of potential foraging spots varied between years, but followed non-random patterns in bathymetry, slope, SST and Chlorophyll a. The results presented here suggest that albatrosses rely on predictable habitat features but are flexible to respond to fine scale changes within their marine environment. The dynamic nature of both birds and environment may prove challenging but has to be taken into account in conservation planning.

Timber harvesting results in patches of regenerating forest that are substantially different from surrounding unharvested stands, and provides an opportunity to investigate the effect of habitat change on forest fauna. In this thesis I used timber harvesting as an experimental treatment to investigate the effect of a changed resource base on the home range and resource selection of the swamp wallaby, Wallabia bicolor. I recorded habitat attributes at unharvested control, recently harvested (<12 months old), 5 year old and 10 year old sites. Initially, harvesting removed almost all above-ground plant biomass, although the nitrogen and water content of grass on recently harvested sites was relatively high. Five years after harvesting, sites were dominated by densely regenerating 1-3 m tall Eucalyptus seedlings. Relative to unharvested sites, there was substantial lateral cover and values of a forage quality index were high. In contrast, 10 year old sites supported dense, closed stands of 3-6 m tall eucalypt regeneration, had a moderate amount of lateral cover and had low values of the forage quality index. (For complete abstract open document)

Foraging decisions of large herbivores can be affected by many factors and have great effect on both above- and below-ground ecosystems. Here, I determine to which degree temporal (seasonality), or spatial (habitat) factors influence the foraging behaviour of Svalbard reindeer (Rangifer tarandus platyrhynchus) and asses if small-scale foraging behaviour correlates with an animals’ patch residence time. I analysed behavioural observations on 15 Svalbard reindeer between summer and autumn 2022, recording both behaviour and habitat use. Using mixed-effects multinomial logistic regression, the interaction between seasonal change from summer to autumn and habitat best explained the variation in Svalbard reindeer foraging behaviour. The foraging behaviour “standing-grazing” was found to have the highest observed amount in all habitat types and increased over the growing season. Contrastingly, the foraging behaviour of “walking-grazing” had its highest abundance in the beginning of the study period, and then decreased over the course of the season for all analysed habitats. In addition, “walking-grazing” was found to be significantly correlated with patch residency time and decreased the longer an individual stayed in a patch. With presumable high plant quality early in the season, my results imply how Svalbard reindeer are greatly stationary foragers, but prioritizing to become relatively mobile when it is beneficial. Thus, highlighting how Svalbard reindeer respond dynamically to shifts in foraging conditions. These findings provide knowledge about what factors may impact the foraging behaviours of Arctic herbivores and helps contribute to a broader understanding of how changes in foraging behaviours may alter arctic ecosystems.

No description available.

Foraging behaviour in Drosophila melanogaster larvae is influenced by natural allelic variation in the foraging (for) gene that encodes a cyclic GMP – dependent protein Kinase (PKG), such that rovers (forR) traverse greater distances while foraging than sitters (fors). Foraging behaviour is also influenced by natural allelic variation in the wings up A (wupA) gene that encodes the Troponin-I protein (TnI). Specifically, wupAlow allele suppresses the dominance of the forR allele, turning rovers into sitters. The dominance of the natural wupA alleles and their interactions with allelic combinations in for has not been characterized. I conducted various crosses and found that wupA alleles exhibit incomplete dominance. More importantly, I found that allelic combinations of wupA and for gave rise to a range in larval foraging behaviour. In this study, I propose that this gradient effect in foraging behaviour is due to variation in levels of PKG activity and TnI phosphorylation potential.

Foraging behaviour in Drosophila melanogaster larvae is influenced by natural allelic variation in the foraging (for) gene that encodes a cyclic GMP – dependent protein Kinase (PKG), such that rovers (forR) traverse greater distances while foraging than sitters (fors). Foraging behaviour is also influenced by natural allelic variation in the wings up A (wupA) gene that encodes the Troponin-I protein (TnI). Specifically, wupAlow allele suppresses the dominance of the forR allele, turning rovers into sitters. The dominance of the natural wupA alleles and their interactions with allelic combinations in for has not been characterized. I conducted various crosses and found that wupA alleles exhibit incomplete dominance. More importantly, I found that allelic combinations of wupA and for gave rise to a range in larval foraging behaviour. In this study, I propose that this gradient effect in foraging behaviour is due to variation in levels of PKG activity and TnI phosphorylation potential.

Das Ziel der vorliegenden Arbeit war es, die Eignung von vierzehn Pflanzenarten des Wirtschaftsgrünlands für die Etablierung von Grasnarben für die Hühnerfreilandhaltung zu untersuchen. Neun Gräser und fünf Kräuter, deren hohe Leistungsfähigkeit aus intensiv bewirtschafteten Systemen, und deren gute Schnitt-, Weide- und Trittverträglichkeit bekannt sind, wurden vergleichend bewertet. In einem Feldexperiment wurde die Verträglichkeit der Pflanzen gegenüber Beweidung mit Hühnern untersucht. Die Hypothese lautete, dass sich die Leistungsfähigkeit der Arten deutlich unterscheiden würde, da die Störung, die durch Beweidung mit Hühnern erzeugt wird, stärker und von anderer Natur ist als in anderen Bewirtschaftungssystemen. Monokulturen und eine Mischsaat der vierzehn Arten wurden einer Umtriebsbeweidung mit Legehennen in drei Stufen der Weidedauer unterzogen. Die Wirkung der Faktoren Pflanzenart, Weidedauer und Umtrieb auf Bodendeckung, Dichte der Triebe und Vegetationspunkte, und Wachstum der oberirdischen Biomasse wurde analysiert. Aus ersteren Zielgrößen wurde die Resistenz der Grasnarbe gegenüber der Beweidung abgeleitet, aus der dritten ihre Resilienz. Die Hypothese, dass sich die untersuchten Arten stark im Hinblick auf ihre Resistenz und Resilienz gegenüber Beweidung mit Hühnern unterscheiden würden, wurde bestätigt. Unsere Ergebnisse deuteten darauf hin, dass Gräser prinzipiell besser für die Bepflanzung von Auslaufflächen geeignet sind als Kräuter. Die Arten Festuca arundinacea und Poa supina zeigten mit einer Bodendeckung von über 80 %, einer konstanten Triebdichte und einer gleich bleibenden, vergleichsweise hohen Wachstumsrate von mehr als 4,8 g Trockenmasse m-2 d-1 die beste Leistungsfähigkeit bei wiederholter Beweidung und langer Weidedauer. In einem ergänzenden Gefäßversuch im Gewächshaus wurde untersucht, welche mit der Wuchsform in Zusammenhang stehenden Eigenschaften die Toleranz der Pflanzen gegenüber Beweidung mit Hühnern erklären. Die Hypothese bestand darin, dass die Biomasseallokation vor der Störung und die Lage von Speicherorganen und Knospen für klonales Wachstum die Schädigungstoleranz bestimmen würden; sie würde bei Arten hoch sein, bei denen diese Organe konzentriert an der Sprossbasis und unterhalb von oder nahe der Erdoberfläche liegen. Eine Auswahl der im Freilandversuch verwendeten Pflanzenarten, die drei Wuchsformen repräsentierte (Arten ohne Ausläufer; Arten mit Stolonen; Arten mit Rhizomen) wurde einer standardisierten mechanischen Schädigung in drei Intensitäten ausgesetzt, welche zugleich auf Spross und Wurzel wirkte. Die Ergebnisse dieses Versuchs zeigten, dass die Pflanzenart, nicht aber die Wuchsform die Toleranz gegenüber Schädigung bestimmten. Die höchste Toleranz wurde bei F. arundinacea und Poa pratensis festgestellt. Der Wiederaufwuchs oberirdischer Biomasse war über alle Arten und Intensitäten der Behandlung hinweg stark mit der relativen Wurzelbiomasse (der Wurzelbiomasse der behandelten Pflanze im Verhältnis zu der der Kontrollpflanze) korreliert, allerdings nicht mit der Wurzelbiomasse vor der Behandlung. Die Resistenz der Wurzel gegenüber mechanischer Schädigung ist daher offenbar eine wesentliche Determinante der Toleranz gegenüber der untersuchten Störung. Schließlich wurde der Einfluss von botanischer Zusammensetzung und Degradierung der Grasnarbe auf das Nahrungssuchverhalten der Hühner untersucht. In dem oben erläuterten Feldexperiment war die Häufigkeit der Verhaltensweisen Picken an Pflanzen, Picken am Boden und Scharren aufgezeichnet worden. Aus den Daten ging hervor, dass Pflanzenart und Degradierung der Grasnarbe das Nahrungssuchverhalten der Hühner signifikant beeinflussten. Eine steigende Weidedauer reduzierte die Bodendeckung grüner Vegetation signifikant; allerdings unterschieden sich die untersuchten Pflanzenarten deutlich im Hinblick auf das Ausmaß der Degradierung, die durch standardisierte Beweidungsdauer erzeugt wurde. Bei steigender Weidedauer und sinkender Bodendeckung grüner Vegetation war bei den meisten Pflanzenarten eine Abnahme der Häufigkeit des auf die Grasnarbe gerichteten Pickverhaltens (Picken an Boden und Pflanzenteilen summiert) nachweisbar. Dieses Ergebnis wird als bedeutsam für das Tierwohl erachtet, da in Umwelten, die wenig Anreiz zu Picken an Objekten bieten, die Gefahr besteht, dass die Tiere vermehrt Federpicken zeigen. Wir leiten aus diesen Ergebnissen ab, dass die Wahl von Pflanzenarten wie P. supina, die sowohl eine hohe Resistenz gegenüber der durch Beweidung verursachten Störung aufweisen, als auch einen starken Anreiz zu Nahrungssuchverhalten, und insbesondere zu Picken liefern, als Begrünung den Beitrag der Auslauffläche zu Tierwohl und –gesundheit fördern können. Zusammenfassend haben unsere Experimente gezeigt, dass die Wahl der Pflanzenart zur Auslaufbegrünung ein wichtiger Faktor zur Gewährleistung der Multifunktionalität der Grasnarbe ist. Pflanzen, die bei langer Beweidung eine stabile Bodendeckung und starkes Wachstum aufweisen, können einen höheren Anteil der im Auslauf anfallenden Nährstoffmengen binden und tragen somit zum Schutz von Boden und Wasser bei. Eine Grasnarbe, die zusätzlich das Nahrungssuchverhalten anregt, begünstigt Tierwohl und -gesundheit. Von den untersuchten Arten zeigte P. supina insgesamt das beste Ergebnis in Bezug auf diese Kriterien; F. arundinacea zeichnete sich zwar durch eine hohe Resistenz gegenüber der Störung durch die Beweidung aus, allerdings schien diese Art weniger stark bepickt zu werden. Wir schließen daraus, dass die Wahl der Pflanzenart für die Auslaufbegrünung als eine wichtige Methode des Auslaufmanagements betrachtet werden kann, die etablierte Methoden der Auslaufpflege, wie Umtriebsbeweidung mit ausreichenden Beweidungspausen und eine Gestaltung des Auslaufs, welche die Tiere zur Nutzung der gesamten Fläche animiert, ergänzen sollte.

Conselho Nacional de Desenvolvimento Científico e Tecnológico / The food niche and the interactions between different groups of bees and plants can be studied, in dissimilar systems, using the association of tools, such as plant-bait, pollen analysis and interaction network approach. In this context, the general aim of this work was to study the interactions between bees and plants in two ecological systems: one natural, using species of Malpighiaceae as plant-baits, and other crop area, using the consortium between eggplant (Solanum melongena) and pumpkin (Cucurbita moschata) as bait plants. In the natural system, observations of the foraging behaviour and the analysis of pollen loads of oil-collecting bees sampled in Byrsonima spp. showed that: 1) the behaviour of foraging for pollen and oil was significantly associated with the taxonomic groups; 2) the main pollen source for these bees was Byrsonima spp. and 3) the robustness of interaction networks was influenced by the removal of bees according to the abundance, body size and taxonomic groups. Additionally, in this system we also studied the food niche of Exomalopsis fulvofasciata. This species foraged in five floral sources (being Byrsonima the most important) and used predominantly small pollen grains and flowers with non poricidal anthers. In the agrosystem, we observed a low similarity in the communities of flower visitors between the two crops that have been exploited for the collection of complementary resources (pollen and nectar). Furthermore, we observed that the complete system, formed by all bee species, both crops and surrounding plants, showed a greater robustness to the removal of species than all the simplest scenarios, except for the exclusion of bees according to their abundance. Thus, the results obtained in this study contributed to a greater understanding of bees-plants interactions in natural areas in Cerrado and crop areas. Information about the foraging behaviour and food niche, associated with simulations of possible extinction scenarios can be used to support actions of conservation and management of pollinators. / O nicho alimentar e as interações entre diferentes grupos de abelhas e plantas podem ser estudados, em sistemas distintos, usando a associação de ferramentas, como planta-isca, análise polínica e abordagem de redes de interações. Nesse contexto, o objetivo geral deste trabalho foi estudar as interações entre abelhas e plantas em dois sistemas ecológicos: um natural, utilizando espécies de Malpighiaceae como plantas-iscas, e outro cultivado, utilizando-se consórcio de cultivos de abóbora-menina (Cucurbita moschata) e berinjela (Solanum melongena) como plantas-iscas. No sistema natural, a observação do comportamento de forrageamento e a análise das cargas polínicas das abelhas coletoras de óleo amostradas em Byrsonima spp. mostraram que: 1) os comportamentos de forrageamentos para pólen e óleo foram significativamente associados aos grupos taxonômicos; 2) a principal fonte de pólen para esses insetos foi Byrsonima spp. e 3) a robustez das redes de interações foi influenciada pela remoção das abelhas de acordo com a abundância, tamanho corporal e grupos taxonômicos. Além disso, nesse sistema também foi estudado o nicho alimentar de Exomalopsis fulvofasciata (Apidae). Essa espécie forrageou em cinco fontes florais (sendo Byrsonima a principal delas) e usou predominantemente grãos de pólen pequenos e flores com anteras não poricidas. Já no agrossistema, foi verificada uma baixa similaridade entre as comunidades de visitantes florais dos cultivos que foram explorados para a coleta de recursos complementares (pólen e néctar). Além disso, observou-se que o sistema completo, formado por todas as espécies de abelhas, ambos os cultivos e as plantas do entorno, apresentou maior robustez quanto à remoção de espécies do que todos os cenários mais simples, exceto quanto a eliminação das abelhas de acordo com a abundância. Assim, os resultados obtidos contribuiram com o Bmaior entendimento das interações abelhas-plantas em reservas naturais de Cerrado e áreas cultivadas. As informações sobre os comportamentos de forrageamento e o nicho alimentar, associada às simulações de possíveis cenários de extinções, podem ser usadas como subsídio para ações de conservação e manejo dos polinizadores. / Doutor em Ecologia e Conservação de Recursos Naturais

L'étude des mouvements et du comportement de plongée des prédateurs marins en relation avec les caractéristiques biotiques et abiotiques de l'environnement permet d'apporter des indications précieuses sur les stratégies comportementales innées et/ou qu'ils ont développé afin de maximiser l'acquisition des proies dans un environnement donné. Le phoque de Weddell est le seul mammifère marin vivant toute l'année dans la banquise permanente. Bien que son comportement ait été bien étudié en été lorsque les individus se reproduisent et muent sur la glace de mer, nous ne savons presque rien de leur l'écologie hivernale. Cependant, l'hiver est une période cruciale dans le cycle de vie des phoques de Weddell durant laquelle ils passent 80% de leur temps à chasser sous la glace afin de stocker l'énergie nécessaire pour la saison de reproduction suivante. Grâce à l'utilisation de données télémétriques, l'objectif principal de cette thèse était d'améliorer notre compréhension des stratégies de recherche alimentaire adoptées par les phoques de Weddell pendant l'hiver dans deux régions de l'Antarctique de l'Est (Dumont D'Urville et Davis). Tout d'abord, nous avons développé deux méthodes permettant d'identifier et de quantifier l'effort de recherche alimentaire au sein de la plongée, pour des données de plongée haute et basse résolutions. Ces indices de l'effort de recherche alimentaire ont été ensuite utilisés afin d'étudier l'influence de plusieurs paramètres clés de l'environnement (topographie, intensité lumineuse, glace de mer, masses d'eau) sur le comportement de recherche alimentaire des phoques de Weddell. / Studying the movement patterns and diving behaviour of top predators in relation with biotic and abiotic environmental features can provide valuable insights in the behavioural tactics they have evolved and/or learned to maximize prey acquisition in a given environment. The Weddell seal is the only marine mammal inhabiting the coastal fast-ice area year-round. While its behaviour has been well studied in summer when individuals are breeding or moulting on the sea-ice, virtually nothing is known about their winter ecology. However, winter is a crucial period in Weddell seals life cycle during which they spend 80% of their time diving under the ice to store the energy needed for the following breeding season. Using telemetric data, the main aim of this thesis was to improve our understanding of the foraging strategies adopted by Weddell seals during winter in two locations of East Antarctica (Dumont D’Urville and Davis). First, we developed two methods to identify and quantify within dive foraging effort from both high and low-resolution dive datasets. Then, these foraging metrics were used to investigate the influence of several key abiotic parameters of the Antarctic environment (topography, light intensity, sea-ice, water masses) on Weddell seals’ foraging behaviour.