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.

Two distinct stress coping strategies, proactive and reactive, have been stated in various animal studies, each associated with a set of behavioural and physiological characteristics. In a given challenging situation, proactive animals show more aggression, a higher general activity and a predominant sympathetic reaction. In contrast, the reactive copers respond more with immobility and avoidance, and a predominant parasympathetic/hypothalamic activation. This divergence in coping has also been indicated in salmonid fish. Interestingly, many of the differences reported between sea-ranched and wild fish resembles characteristics that differentiate proactive and reactive copers. In the present thesis it is shown that individuals with divergent stress coping styles are identifiable in several brown trout (Salmo trutta) populations. Further, the results show that the distribution of individuals displaying these distinct stress coping strategies differs between populations. This strongly indicates that these traits are heritable and that the variation in selection regime in the native rivers influences these traits. In addition, the results show that populations with hatchery origin are biased towards having higher frequencies of trout displaying a proactive style than populations having wild origin. Also, even though the frequency of early sexual maturation, known as a viable alternative life history in salmonids, differs between populations of brown trout, no link between stress coping strategy and early sexual maturation were found. However, this thesis show that maternal contribution, in the form of egg size, is of major importance whether the progeny will sexually mature early and that it also might be of importance for stress coping strategy. Further, correlations of traits commonly associated with stress coping strategies and behavioural syndromes across context and over time is investigated. The results show that individuals with a strong sympathetic reactivity are more prone to change their behaviour than others.

Rainbow trout (Oncorhynchus mykiss) are introduced in large parts of the world and are commonly farmed for consumption as well as a valued sport fish. Many species of salmonids show large intraspecific variation in pigmentation, which has been shown to correlate with stress response and several other behavioral traits. In this study, the behavior and stress response of rainbow trout linked to pigmentation is investigated, depending on previous sport fishing experience. Through data from a previous study on rainbow trout in semi-natural ponds, locomotor activity was measured as a proxy of stress, under three different sport fishing treatments. From previous photos, the pigment spots of each rainbow trout are counted to test the correlation with locomotor activity. In addition, it is tested whether different previous experience of sport fishing means a higher stress response when re-exposed to fishing. No significant relationship between pigment spots and locomotor activity could be obtained for the three treatment groups. However, significant differences in locomotor activity due to angling experience between treatment groups upon re-exposure to fishing were found, with fish that were inexperienced in angling having higher locomotor activity compared to previously caught fish. Sport fishing and catch-and-release had the effect of reducing locomotor activity in rainbow trout, which can be interpreted as fishing could both stress them and trigger the fish's feeding response, depending on previous experience. Fishing is believed to create a passivation due to the negative association of being caught, while fish not previously caught were activated by sport fishing. The study's missing correlation between pigment spots and stress has been both confirmed and denied in other studies and may depend on the origin and the degree of domestication, which means that the correlation within other species of salmonids or fish with different origins would be relevant to investigate. / Regnbåge (Oncorhynchus mykiss) förekommer introducerade i stora delar av världen och är vanliga att odlas för konsumtion samt en uppskattad sportfisk. Många arter av salmonider visar stor intraspecifik variation i pigmentering, vilket visats korrelera med stressrespons och flera andra beteendemässiga karaktärsdrag. I denna studie undersöks regnbågarnas beteende och stressrespons kopplat till pigmentering, beroende på tidigare erfarenhet av sportfiske. Genom data från en tidigare studie på regnbåge i semi-naturliga dammar mäts rörelseaktivitet som indirektmått på stress, under tre olika sportfiskebehandlingar. Från tidigare foton räknas varje regnbåges pigmentfläckar för att testa korrelationen med rörelseaktivitet. Därtill testas om olika tidigare erfarenhet av sportfiske, innebär högre stressrespons vid återexponering för fiske. Inget signifikant samband mellan pigmentfläckar och rörelseaktivitet kunde erhållas för de tre behandlingsgrupperna. Signifikanta skillnader i rörelseaktivitet på grund av erfarenheten av sportfiske mellan behandlingsgrupperna vid återexponering för fiske fanns dock, där fisk som var oerfaren sportfiske hade högre rörelseaktivitet jämfört med fisk som fångats tidigare. Sportfiske och catch-and-release hade effekten att minska rörelseaktiviteten hos regnbågar, vilket kan tolkas som att fisket både kunde stressa och trigga fiskens födorespons, beroende på tidigare erfarenhet. Fisket tros skapa en passivisering på grund av den negativa associationen att bli fångad, medan fisk som inte fångats tidigare aktiverades av sportfisket. Studiens uteblivna samband mellan pigmentfläckar och stress har både bekräftats och dementerats i andra studier och kan bero på ursprung och graden av domesticering, vilket gör att sambandet inom andra arter av salmonider eller fisk med olika ursprung vore aktuellt att undersöka.