To cope with a changing environment, animals have traditionally been considered to behave adaptively to each situation faced. Yet, individual behavioural responses can both differ widely within populations, and show between-individual consistency (i.e. describing variation in animal personality). In this thesis, I focus on individual differences in animal personality and cognition (i.e. how animals perceive, process, store and act on environmental stimuli), and explore the possibility that they are interlinked. I use domestic- and red junglefowl (Gallus gallus ssp.), a species that is cognitively, behaviourally and socially complex, to explore these aspects of behaviour, through a series of studies. Animal personality and coping styles are frequently used terms to describe within- and between-individual differences in behaviour, which are consistent over time and across various situations. The terms are often used as synonyms, even though they differ in some respects. In paper I, I show that animal personality and coping styles can be measured in red junglefowl, and that behavioural flexibility might be an important aspect for both. Further, I show that the terms should not be used as synonyms since they describe different aspects of behavioural variation. In paper II, I observe large individual variation in both personality traits and learning speed in both chicks and adult red junglefowl. Interestingly, learning performance does not correlate across tasks, contrasting what has been found in humans and rodents. Thus, individuals that learn rapidly in one task are not necessarily fast learners in another task. I observe a relationship between personality and cognition that is task- and age-dependent, in which exploration relates to learning speed, but in opposite directions for chicks compared to adult females. In paper III, I show that red junglefowl chicks that are more behaviourally flexible have a stronger preference for new generalised stimuli, than less behaviourally flexible chicks. Behavioural flexibility was associated with fearfulness, indicating variation in reactive-proactive coping styles. In paper IV, I show that early cognitive stimulation to some extent can affect adult personality, thus showing a causal relationship between personality and cognition. Not all personality traits were affected, which might depend on the type of cognitive stimulation chicks were exposed to. Important cognitive processes like perception and decision-making, can contain biases. One such bias is called judgment bias, which describes how individuals interpret ambiguous stimuli on a scale from positive to negative (optimism to pessimism). In paper V, I show that alteration of emotional state can influence such biases. Here, unpredictable stress influence judgment bias negatively, when individuals are housed in simpler, but not in complex environments, suggesting that there is an effect of additive stress that lead to reduced optimism. Complexity instead seems to buffer against negative effects of stress, since individuals in complex environments remained optimistic after stress exposure. Furthermore, increased dopamine activity was associated with optimism in chicks. In paper VI, I find that aspects of personality associate with how chicks judge ambiguity. Highly active individuals are more likely to approach cues than less active individuals, and when approaching, individuals that are slow to approach ambiguous cues are more vigilant when assayed in personality assays. Vigilant individuals might be more worried and reactive, which suggest that emotional traits can influence responses in a judgment bias task. Taken together, I show consistent behavioural differences among individuals describing personality and coping styles, and variation in cognition. I show that these traits are related, and that there is an interplay between them, in which cognition can influence personality, and vice versa. I further show that judgment may be affected by the individual’s current affective state and personality. Thus, I show a complex relationship between personality and cognition that in combination with environmental effects can help explain behavioural variation.

Senescens, in common language aging, remains one of the most poorly understood phenomena in biology. However, one thing we do know for sure, is that all individuals will age, and that all who are now young and fertile will eventually get old, and lose their ability to be as susceptible to changes in the environment as they were before. The question is why certain species and individuals become much older than others. With this master thesis, I aim to investigate what evolutionary and physiological factors cause the naked mole rat to become so much older than other similar sized rodents. The study is based on a synthesis of scientific articles and scientific books, and the results showed that eusociality, fossoriality, stress resilience, high H₂O₂ consumption, and high levels of copper and zinc superoxide dismutase may be potential factors in why the naked mole rat becomes so much older than other similar sized rodents. To completely understand the factors that influence the senescence of the naked mole rat is difficult, as the phenomenon of senescence is still a bit of a mystery in biology. But with further research and further studies about the topic, one may in the future be able to understand which factors completely affect the slow senescens of the naked mole rat, and then also get important information to another researches about senescence. / Senescens, i vardagligt språk åldrande, är fortfarande ett av de minst förstådda fenomenen inom biologin. En sak vi vet säkert är dock att alla individer åldras, och att alla som nu är unga och fertila, kommer med tiden att åldras och förlora sin förmåga att vara lika mottagbara för förändringar i miljön som tidigare. Frågan är dock varför just vissa arter och individer blir så mycket äldre än andra. Med denna litteraturstudie på magisternivå vill jag undersöka vilka potentiella evolutionära och fysiologiska faktorer som gör att just nakenråttan blir så mycket äldre än andra jämnstora gnagare. Studien är baserad på en sammanställning av vetenskapliga artiklar och vetenskapliga böcker, och resultaten visade att eusocialitet, fossorialitet, stresstålighet, hög H₂O₂ förbrukning, och höga halter av koppar och zink superoxiddismutas kan vara potentiella faktorer till varför nakenråttan blir så mycket äldre än andra jämstora gnagare. Att fullt förstå vilka faktorer som påverkar nakenråttans senescens är svårt eftersom just fenomenet senescens fortfarande är lite av ett mysterium inom biologin. Men med vidare forskning och ytterligare studier inom området, så kanske man i framtiden kan förstå vilka faktorer som helt påverkar nakenråttans långsamma åldrande, och då även få viktig information med sig till annan forsning om just senescensen.

Dolphins at Kolmården dolphinarium were given a set of 20 floating fish hides, in order to simulate aforaging situation. The idea was to motivate the dolphins to use echolocation, in order to differentiatebetween hides which contained fish and hides that were empty. The dolphins would access the fish hidesfor 20-minute sessions five days per week, during a total period of five weeks. The results indicated thattheir interest in the fish hides was maintained over the entire study period for all individuals, and thisinterest did not correlate with age. However, older dolphins seemed more prone to solely inspect, possiblyby using echolocation aimed towards the fish hides than to physically interact with them. Neither was theirinterest affected by the dolphins’ pre-session activities. However, not all dolphins seemed interested in fishunless given to them by care takers. Thus, some dolphins were likely less motivated in solving theecholocation task. As a pod, the dolphins’ interest in this innovative enrichment was maintained over time,and the plasticity of these fish hides would suggest a range of different setups for the future. However,when analysing the potential use of echolocation cues, theoretical calculations of the target strengthdifferences between filled and empty fish hides, together with data on the physical interactions with them,suggested that the dolphins did not use sonar cues, but resorted to more or less random manipulation of thefish hides in order to eject the fish.

Piglet mortality is a widespread problem in pig productions today. In Sweden were the average mortality rate 16,9% year 2021 from birth to weaning. The most common cause is starvation and crushing by the sow. A pig production outside of Eskilstuna has problems with sows that crush their piglets, especially during the night when nobody is working. They have therefore decided to change number of feedings for sows. The purpose of this study is to evaluate whether the change in the feeding routine reduces piglet mortality and the behaviour of the sows and piglets. The piglets and sows were observed during the week of farrowing and the week after and the number of pigs that died during this period were noted. The results were analysed later in the program RStudio. The results showed some difference in behaviour between the sows and the piglets but no significant difference in piglet mortality between the groups. The results suggest that the change in number of feedings did not affect the piglet mortality and the pig production should therefore explore other factors affecting their high mortality rate. / Smågrisdödlighet är ett vida känt problem i grisproduktioner idag. I Sverige låg den genomsnittliga smågrisdödligheten från födsel till avvänjning på 16,9% år 2021. De mest vanliga orsakerna är svält och att suggan lägger sig på smågrisarna. En grisproduktion utanför Eskilstuna har problem med att suggan lägger sig på sina smågrisar, speciellt under natten när ingen är närvarande. Därför har de bestämt att ändra antalet utfodringar för suggor i BB-avdelningen. Syftet med den här studien är att utvärdera om det blir någon skillnad i smågrisdödlighet i samband med ändrade utfodringsrutiner. Grisarna observerades under grisningsveckan och efterföljande vecka och antalet smågrisar som dog i respektive grupp under observationsperioderna antecknades. Resultaten analyserades senare i programmet RStudio. Resultaten visade några skillnader i beteende hos både suggor och smågrisar men ingen signifikant skillnad i smågrisdödligheten kunde hittas mellan grupperna. Resultaten pekar därför på att ändringen av antalet utfodringar inte påverkade smågrisdödligheten utan produktionen bör utvärdera andra möjliga faktorer som kan påverka smågrisdödligheten.

A recent theory within behavioural ecology suggests that some animal behaviour traits are consistent over time and over different contexts as part of an animals’ “personality”. Animal personality has generally been accepted within vertebrates, but the idea of invertebrates expressing personality has long been meet with scepticism. In this study, I investigate if red wood ants (Formica rufa) show exploratory and bold behaviours that fulfil the personality criteria. Moreover, I test if this species prefers dark surfaces instead of white surfaces (scototaxis). My experiment included tests of 30 ants and two different behaviour trials targeting exploration and boldness that repeated over three different time periods. My results shows that the exploratory behaviours were correlated between trials conducted at different times and therefore, that this behaviour was repeatable. It was also clear that the red wood ant consistently showed large between individuals, indicating difference in personality. However, the studied ants did not show preferences for dark surfaces and the performance in the scototaxis trial did not correlate with any other measurable behaviour. The result of this study suggests that Formica rufa show behaviours that match the animal personality criteria for exploratory behaviour, but my result could not validate that bold behaviours were repeatable across time and context.

Stress can induce prolonged deleterious effects on many characteristics in chickens (Gallus gallus). Particular interest has been paid to early life stress. Social isolation as an early life stressor results in increased plasma corticosterone levels. Moreover, it induces behavioural and physiological changes as well as gene expression modifications in the hypothalamus. In the first part of my study, I aim to inquire into social isolation impacts on the short and long-term. Short and long-term effects were assessed by immune system, behaviour and weight. 82 male chickens were assigned to three groups (stress, control and enrichment). The stress group was exposed to social isolation, the enrichment group was provided with enrichment substrates while the control group was left untreated. According to my knowledge, this is the first study that investigates the effects of social isolation on the interuleikn-6 levels as an indicator of immune system response. My findings suggest that social isolation induces short and long-term effects on immune response as well as on body weight. In the second part of my study, I aim to develop a method investigating effects of early stress on DNA methylation in blood and sperm. For this purpose, two methods GBS (Genotyping by sequencing) and MeDIP (Methylated DNA immuneprecipitation) were f using pooled DNA from all individuals for the first time. Moreover, I developed a protocol for extracting sperm DNA from frozen testis. Combining both methods has many advantages, such as cost effectiveness and the ability to evaluate epigenetic signatures in large number of individuals

Cognition (i.e. how individuals perceive, process and react to environmental cues) is fundamental to all animals’ life. Despite this, what explains variation in cognitive abilities is still mainly unclear. Environment is assumed to influences cognitive variation, but the mechanisms for this are still unknown. According to the social intelligence hypothesis, living in a group with a rich social environment, generate challenges that can enhance cognitive abilities. Impulsivity (to not be able to inhibit impulses), one aspect of cognition, may be influenced by the social environment, however this has not yet been experimentally tested. Impulsivity can complicate life, both for humans and animals. In humans, high levels of impulsivity and lack of self-control are associated with addictions and psychiatric disorders, thus is considered to be maladaptive. In animals, impulsivity correlates with stereotypies. To improve our understanding of impulsivity, I experimentally investigated how early social environment affects individual variation in impulsivity. To test this, red junglefowl chicks were used because their group living nature, and our accumulated knowledge on their cognition and behaviour. To manipulate the social environment, chicks either grew up in larger groups (with 17 individuals) or smaller groups (with 7 individuals). During the chicks’ first five weeks of life, three aspects of impulsivity were tested; impulsive action, persistence (in a detour reaching test) and routine formation (in a reversal learning test). Chicks that grew up in larger groups tended to perform less impulsive actions, while social environment did not explain variation in persistence. Chicks from larger groups had less strong routine formation compared to chicks raised in smaller groups. This partially supports the social intelligence hypothesis, and suggest that early social life can affect cognitive traits and explain individual variation in such.

With the different threats sea turtles are currently facing, such as habitat reduction and pollution, increase of fishing and harvesting of aquatic resources by Humans, or invasive species, it is important to learn as much as possible about their biology and behaviour in order to ensure the success of conservation programs. In this study, loggerhead sea turtles (Caretta caretta) feeding behaviour duration as well as energy expenditure approximation during a feeding event were tested and compared using two different types of food: green shore crabs (Carcinus maenas) or Japanese clam (Ruditapes phillipinarum) or Venus clams (Chamelea gallina). The data show that the turtles took longer to approach the crabs but took more time to eat the clams. However, comparison of energy expenditure values for the feeding phase showed no significant differences. The turtles were observed to eat the clams’ shell as well as their meat. These shells are rich in calcium, which is one possible explanation for this behaviour. This study shows that data loggers represent a viable tool for studying the behaviours of marine animals.

It is now widely accepted that the concept of ”animal welfare” includes both the physical and mental wellbeing, and that providing positive experiences is equally important as avoiding and limiting negative ones. Most scientists seem to agree that horses experience positive welfare when exploring and feeding in complex environments and through friendly interactions with other members of the flock. In contrast, it is less clear in which situations they experience positive welfare when kept in captivity and their natural behaviours are restricted. We need indicators to assess if animals experience positive welfare, and the first aim of this thesis was a summary of the research on this subject presented the last decade. The indicators can be divided into signs of enjoyment and content (for example facial expression, body language and vocal and non-vocal sounds), luxury behaviours (behaviours not necessary for survival, such as play or allogrooming) and behaviours that supports the possibility to cope with challenges (such as friendly interactions or the possibility to control a situation). Since research has progressed so much the last decade, the second aim of this thesis was to create a checklist to be used when assessing the positive side of the welfare spectrum. However, it became clear that there is still need for more research before the indicators of positive welfare can be used in practice in a detailed checklist. This is partly due to the need for special equipment for analysis of some indicators and because many results were inconclusive or dependent on a specific context. The checklist is therefore limited to how to exclude that the horse experience negative welfare, how to provide more that the minimum level stated in the animal welfare legislation and how to provide daily possibilities to experience positive feelings. / Numera är det allmänt accepterat att begreppet ”djurvälfärd” omfattar både fysiskt och mentalt välbefinnande, och att god djurvälfärd innebär att erbjuda möjlighet till positiva upplevelser likaväl som att undvika och begränsa negativa. De flesta forskare verkar överens om att hästar upplever positiv välfärd när de ägnar sig åt utforskande och födosökande beteende i stimulansrika miljöer och interagerar vänligt med andra flockmedlemmar. I vilka situationer de upplever positiv välfärd då de hålls av människan, och de naturliga beteendena begränsas på olika sätt, är däremot mer oklart. För att kunna bedöma om djur upplever positiv välfärd måste man använda olika indikatorer, och denna uppsats sammanfattar det senaste decenniets forskning på området. Indikatorerna kan delas upp i tecken på belåtenhet eller njutning (t.ex. ansiktsuttryck, kroppsspråk och vokala och icke-vokala ljud), lyxbeteenden (dvs beteenden som inte är nödvändiga för djurs överlevnad som lek och allogrooming) och beteenden som understödjer möjligheten att hantera utmaningar (t.ex. vänskapliga interaktioner eller att kunna kontrollera sin situation). Eftersom forskningen gått så mycket framåt det senaste decenniet var målsättningen också att skapa en checklista som behandlar den positiva halvan av välfärdsskalan. Det visade sig dock när indikatorerna var sammanställda att det fortfarande krävs en hel del forskning innan de är praktiskt användbara i en så detaljerad checklista. Detta beror bland annat på att flera indikatorer kräver specialutrustning för analys och för att flera resultat var tvetydiga eller kontextberoende. Checklistan begränsas därför till att behandla hur man utesluter att hästen upplever negativ välfärd och erbjuder mer än miniminivån i djurskyddslagstiftningen samt erbjuder daglig möjlighet till att uppleva positiva känslor.

Captive environments like zoo exhibits offer limited space, lacking many of the environmental stimuli that are present in the wild. This may reduce animal welfare and potentially lead to the development of stereotypic behaviour like pacing. Environmental enrichment is used to prevent and reduce pacing and enhance animal well-being. The aim of this project was to evaluate sensory enrichments, and the effect of such enrichment on pacing in a group of Northern lynx by means of new, automated monitoring technologies in combination with traditional visual observations. The lynxes were exposed to valerian, catnip and cinnamon as olfactory enrichment. The acoustic enrichments were play-backed mouse squeals, roe deer barking and lynx vocalizations, and live crickets. The responses of the lynx were recorded by logging their subcutaneous HDX pit tags, and Bluetooth Low Energy (BLE) tags mounted on collars and using a wildlife camera. The results showed that catnip elicited clear “catnip responses” i.e sniffing, rubbing, biting and licking. The sounds were found to attract the lynxes and increase their arousal. One of the sounds, the lynx calls, elicited social behaviour. However, none of the sensory treatments reduced pacing. The combination of these automated technologies with visual observation was powerful to evaluate the effect of enrichment on captive lynxes and to monitor their activity patterns and stereotypic behaviours. Sensory enrichment could also be used in the wild as lures to attract lynxes to BLE or HDX PIT tag logging stations and to wildlife cameras, as part of monitoring a lynx population.