Syftet med denna studie var att undersöka om det fanns olika personlighetstyper hos mjölkkor av raserna SRB och SLB och om dessa personlighetstyper skilde sig mellan ras, ålder och vilken sida djuren stått på i lösdriften. Korna observerades i tre olika testmiljöer för att se huruvida konsistenta de var i deras beteenden: ostörda i lösdriften, vid mjölkning och med ett främmande objekt i lösdriften. Beteenden som studerades var normala beteenden, sociala beteenden, tramp och sparkningar vid mjölkning och interaktioner med det främmande objektet. Tolv beteendevariabler användes i en PCA (principal component analysis) och visade två komponenter som tillsammans kunde förklara 51,2 % av den totala variansen. Den första komponenten speglade aggression och extraversion, som ingår i medgörlighet och extraversion i den mänskliga femfaktorsmodellen. Den andra komponenten speglade ett mer introvert beteende och rädsla, som går under extraversion och neuroticism i samma modell. Oberoende T-test visade inga signifikanta skillnader mellan någon av komponenterna och ras eller sida i lösdriften p>0,05, däremot en tendens till skillnad mellan den första komponenten och ålder, där den äldre gruppen individer visade tydligare personlighetsdrag p<0.1. Tidigare studier har visat att personlighetsdimensioner som medgörlighet, neuroticism och extraversion ofta förekommer bland flera arter. Då olika personligheter hanterar stressfulla situationer på olika sätt, är detta ämne av stor vikt när det gäller förbättrandet av djurens välfärd. / The purpose of this study was to investigate if different personality dimensions existed in dairy cows of two breeds (SRB and Holstein) and if these personality dimensions differed between breed, age and how the animals were placed in the loose housing system. To investigate behavioural consistency, the cows were observed in three different situations: uninterrupted in their home pen, during milking and with a novel object in their home pen. Normal and social behaviour was observed as well as stepping and kicking during milking and interactions with the novel object. Twelve behavioural variables were used in a principal component analysis, which showed two components that together explained 51,2 % of the total variance. The first component reflected aggression and extraversion, which are included in agreeableness and extraversion in the human five-factor model. The second component reflected fear and introversion, which are included in neuroticism and extraversion in the same model. Independent-samples T test showed no significant differences between any of the components and breed or placement in the loose housing system p>0,05, however there was a tendency between the first component and age, where the older group showed a more defined personality p<0,1. Other studies have showed that personality dimensions such as agreeableness, neuroticism and extraversion often exist in several species. Different personalities cope with stressful situations in different ways, making this topic relevant to the improvement of animal welfare.

Ökad kunskap om djurs beteendesyndrom kan möjliggöra förbättrade bevarandeåtgärder för hotade arter. I den här studien genomgick 108 blankålar (Anguilla anguilla) två beteendetester; “open-field test” och “novel-object test”. Ålars morfologi och val av föda, habitat och dygnsaktivitet har i tidigare studier visats hänga ihop. I den här studien undersökte jag om det fanns något samband mellan ålarnas morfologi, aktivitet samt respons på främmande föremål. De ålar som var mest aktiva under open-field-testet var också de ålar som visade störst intresse för det främmande föremålet i novel-object-testet. Det fanns dock inte något samband mellan morfologi och aktivitet eller mellan morfologi och respons på främmande föremål. Detta innebär att ett utforskande och djärvt beteendesyndrom har upptäckts hos vissa av ålarna, medan den bakomliggande faktorn fortsätter vara okänd. / Increased knowledge of behavioural syndromes may contribute to enhancing our conservation methods for endangered species. In this study, the behavior of 108 silver eels (Anguilla anguilla) was assessed in two assays: an open-field test and a novel-object test. Eel morphology and diel activity as well as diet and habitat use have previously been shown to correlate with each other. In this study, I investigated the potential relationship between the morphology, activity and response to a novel object. The most active eels during the open-field test were also the ones that expressed the most interest for the novel object. There was, however, no correlation between morphology and activity or morphology and response to the novel object. This means an exploring and bold behaviour syndrome was discovered amongst some of the eels, whilst the underlying cause remains unknown.

Throughout the animal kingdom, individuals often differ consistently from one another in how they cope with their environment. In particular, consistent behavioural variation, known as animal personality, is a substantial driver of a range of important ecological and evolutionary processes. As most animal species are social for at least part of their lives and group living is common, a crucial link between personality and the social context may be expected. In this thesis I systematically investigate this link, using three-spined stickleback fish (Gasterosteus aculeatus) as my model system. I begin by showing that fish vary consistently in their boldness and sociability, with only boldness being positively linked to food intake for fish at rest. This finding provides support for evolutionary theory that links personality variation to life-history strategies, and lays the basis for work related to the social context. I continue by investigating how the social context may modulate personality variation and show that short contact with a social group may have carry-over effects and obfuscate personality expression when individuals are alone. Next, I observed fish in different pairs over time and found that social experience from both the current as well as previous social contexts are integrated in the risk-taking and leadership decisions of individuals but also depends on their boldness type. This result provides support for the importance of social feedback in the expression of personality differences. I go on to demonstrate that, in a pair, bolder fish have lower social attraction, with positive effects on individual’s leadership but negative effects on social coordination. Finally, by detailed tracking of the collective movements and group foraging of free-swimming shoals, I reveal boldness and sociability have complementary driving effects of on social structure, collective behaviour, and group functioning. Furthermore, I show that in turn the group composition determines the performance of individual personality types, providing a potential adaptive explanation for the maintenance of personality variation. Taken together, these studies provide an integrated account of animal personality and the social context and highlight the presence of a feedback loop between them, with personality variation being a key driver of collective behaviour and group functioning but also strongly affected and potentially maintained by it.