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Many animals are social foragers. Foraging with others may confer a number of advantages, but is also likely to present a number of challenges that are not encountered by solitary foragers. For instance, whilst feeding in a group may interfere with an animal's ability to learn new foraging skills or the location of new foraging patches by itself, it may simultaneously provide it with the opportunity to acquire new skills or knowledge by means of social learning. This thesis addresses a number of questions relating to the interaction between social foraging and social learning using small groups of captive budgerigars, Melopsittacus undulatus, as a test species. In particular, it investigates the spread of novel foraging behaviour through groups of birds under conditions that either permit or restrict a high degree of ‘scrounging' (food stealing) by naïve birds from skilled ‘producers' in their group (Chapter Three). Scrounging is found to inhibit naïve budgerigars' performance of new foraging skills, but appears to facilitate their underlying acquisition, or motivation to acquire these skills, when the need arises – for instance, when producers are lost from their group. In addition, the thesis assesses the importance of a number of different individual-level characteristics, such as age, sex, and competitive rank, in predicting birds' propensity to behave as producers rather than scroungers when foraging in a group (Chapter Four). The thesis also examines budgerigars' relative use of social and personal information when selecting foraging locations (Chapter Five), and assesses the importance of group social networks in predicting individual birds' order and latency to arrive at foraging patches (Chapter Six). Budgerigars are found to rely on social information when they lack any personal information about foraging locations. When equipped with both social information and personal information, some, but not all birds appear still to utilise social information. Birds' social networks appear to have little bearing on individuals' foraging patch visitation times.

Made available in DSpace on 2016-07-27T14:20:00Z (GMT). No. of bitstreams: 1 RAPHAEL MOURA CARDOSO.pdf: 1296913 bytes, checksum: 8b2625c1a0fa267fe8ef037e09343e1c (MD5) Previous issue date: 2008-09-19 / Pesquisas prévias indicam que os processos de facilitação social e intensificação do estímulo podem aumentar a aceitação de um item alimentar desconhecido dentro de grupos de macacos-prego. Os macacos-prego forrageiam em grupo e o sucesso individual é afetado pelo comportamento de outro membro do grupo. Ademais, os adultos de macacos-prego são socialmente tolerantes, principalmente em relação aos imaturos. Por exemplo, durante o processamento de frutos encapsulados os imaturos permanecem próximos ao indivíduo que processa o alimento, ou mesmo surrupiam pequenos pedaços de alimentos consumidos pelos companheiros. A tolerância, por sua vez, é considerada como um aspecto que favorece a troca de informações sociais em um grupo. Em Cebus nigritus, por exemplo, a emissão de assobios afeta o comportamento da audiência em relação à escolha de onde buscar alimento. Em contextos de exploração de uma fonte alimentar, o macaco-prego do cerrado (Cebus libidinosus) também emite assobios que, em geral, atraem outros indivíduos à fonte alimentar. No presente trabalho, realizamos experimentos envolvendo a apresentação, em uma estação alimentar (EA), de 20 itens alimentares conhecidos e 20 desconhecidos a um grupo semi-livre de Cebus libidinosus do Bosque Laranjeiras em Goiânia (16°43 S: 49°13 W). durante as sessões, registrávamos: o sexo e a faixa etária dos indivíduos em contato com a EA, a 05m e a 10 m da EA, em intervalos de 1 minuto; todas as ocorrências de interações que envolviam o interesse pelo alimento em posse de outro, e a identidade dos sujeitos envolvidos. Todas as sessões foram filmadas e gravadas digitalmente. Para cada indivíduo filmado na EA somamos o número de notas e sílabas de assobios foram contabilizadas a partir de sonogramas gerados pelo programa Avisoft LabPro 4.39. O tamanho e composição do grupo presente na área experimental foram similares entre as duas condições (alimento familiar e alimento novo), e indicou tolerância em relação à proximidade de imaturos. Os macacos mostraram-se sensíveis à novidade alimentar, emitindo mais comportamentos exploratórios e menos de familiaridade nesta condição. A probabilidade de ocorrência de interações do tipo Interesse pelo Alimento do Outro foi significativamente maior na condição onde o alimento apresentado era desconhecido ao grupo. A emissão de assobios foi maior na condição em que o alimento era familiar e apresentou uma correlação negativa com comportamentos de inspeção (uma medida indireta de novidade alimentar). Nossos resultados corroboram a ideia de que a tolerância e a troca de informações entre os indivíduos podem compensar os custos associados à competição durante o forrageio social, em particular no caso de informações sobre novos recursos. Sugerimos novas investigações sobre o papel das vocalizações associadas ao alimento no processo de aprendizagem de quais itens desconhecidos são seguros ou não.

The current study utilized two experiments to assess Smith's (1981) simple per capita-maximization model, which provides a quantitative framework for predicting optimal group sizes in social foraging contexts. Participants engaged in a social foraging task where they chose to forage for points exchangeable for lottery prizes either alone or in a group that has agreed to pool and share all resources equally. In Experiment 1, groups (“settlements”) of 10 or 12 participants made repeated group membership choices. Settlements were exposed to three conditions in which the optimal group size was either 2, 5, or 2 for the 10 person settlement or 3, 4, or 6 for the 12 person settlement. A linear regression of the data from Experiment 1 revealed a strong relationship between the observed group sizes and group sizes predicted by the simple per capita maximization model. Experiment 2 was a systematic replication of Experiment 1 in which single participants foraged for shared resources with groups of automated players in a computerized simulation. Automated player group choices mirrored group choices of participants in Experiment 1; excluding the data for the best performing participant. Thus, the participant acted essentially in the stead of the best performing participant for each condition. Two logistic regressions provided mixed support for the model, while failing to replicate the results of Experiment 1, providing mixed support for the use of the simple per capita maximization model in predicting group sizes in social foraging contexts.

En biologie évolutive, la variation phénotypique a longtemps été réduite au substrat sur lequel agissait la sélection naturelle. Toutefois, la constance intra-individuelle et le maintien intra-populationnel de certains comportements conduisirent au milieu des années 90 au développement du concept de personnalité animale, basé sur la caractérisation de traits tels que la néophobie, l’agressivité, les tendances exploratoires ou la prise de risque. De nombreuses études montrent que la personnalité est soumise à la sélection naturelle et est reliée à certaines stratégies biodémographiques, telles que la dispersion ou le comportement anti-prédateur.Les liens entre la personnalité animale et les stratégies d’appariement et d’approvisionnement, deux composantes fondamentales de la vie des organismes, ont pourtant été négligés jusqu’ici. Nous nous sommes donc attachés au cours de cette thèse à déterminer l’influence de la personnalité sur certains comportements sexuels et alimentaires à l’aide d’un organisme modèle en écologie comportementale : le Diamant mandarin (Taeniopygia guttata). Puis, à l’inverse, nous avons souligné le rôle des sélections naturelle et sexuelle dans le maintien des variations de personnalité.Nos principaux résultats indiquent que certains traits de personnalité mesurés sont inter-corrélés au niveau de notre population captive d’oiseaux, définissant un syndrome comportemental. De plus, la personnalité prédit de manière différentielle le succès d’approvisionnement entre les contextes de compétition par exploitation et par interférence. Ainsi, les individus proactifs sont dominants lors d’épisodes de compétition par interférence mais souffrent d’un plus faible succès d’approvisionnement lors de jeux producteur-chapardeur. Ces résultats soulèvent la possibilité que la sélection naturelle favorise différentes personnalités dans différents contextes, offrant un mécanisme d’explication du maintien des variations intra-populationnelles de personnalité. De plus, ils suggèrent que la personnalité contraint l’optimalité des comportements à travers les situations. Enfin, dans un contexte de choix du partenaire, nous avons montré que la personnalité des femelles utilisées dans des tests de préférence par association influence les mesures de la sélectivité, des scores de préférence et de leur répétabilité.L’étude conjointe de la personnalité animale et des stratégies d’appariement et d’approvisionnement constitue ainsi une voie prometteuse dans l’explication du maintien des variations de personnalité par sélections naturelle et sexuelle, ainsi que dans l’étude de l’influence de la personnalité sur les stratégies biodémographiques des organismes en contextes alimentaire et sexuel / In evolutionary biology, phenotypic variation has for a long time been considered as the raw material on which natural selection acts. However, research on the consistency of behaviour led to the development of the animal personality concept during the 1990s. This concept was based on the characterization of traits such as neophobia, aggressiveness, exploratory tendencies and risk-taking behaviour. Since then, several studies have shown that personality can evolve through natural selection and is related to many life-history traits, such as dispersal or anti-predator behaviour.Pairing strategies and foraging strategies are two fundamental components of an organism’s life, but their relationships with personality have so far been neglected. In this thesis, we determined the extent to which personality influences sexual and feeding behaviour, using the zebra finch (Taeniopygia guttata) as a model organism. Our work highlights the role of natural and sexual selection on the maintenance of personality variation.Some personality traits are related to each other within our sample, defining a behavioural syndrome. Moreover, personality predicted feeding success in competitive situations, but differently for scramble and interference competition. Proactive individuals were dominant in interference competition but had lower feeding success in producer-scrounger games. Interestingly, these results suggest that natural selection could favour different personalities depending on the context, perhaps explaining the maintenance of personality variation within populations. Moreover, personality could constrain behavioural optimality across situations. Finally, in a mate-choice context, we found that female personality influences selectivity, preference and its repeatability during spatial association tests.The joint study of personality and pairing and foraging strategies thus represents a promising avenue of research for understanding the maintenance of personality variation through natural and sexual selection. Moreover, personality can considerably influence some life-history traits in sexual and foraging contexts