Behaviours are the result of the interaction between genetic factors, past experiences, and labile environmental and social influences. Usually, the behavioural variability of an individual is smaller than the behavioural range of its species, but stable over time and contexts. This intraindividual consistency has been termed animal personality, and is found in a wide range of taxa. Personality types have various fitness and behavioural consequences. In particular, proactive individuals seem to perform better in most, but not all, learning tasks. Furthermore, personality types may also influence behavioural reaction towards the task at hand. For instance, in the literature, reactive individuals are expected to explore new environments more slowly, but to respond better to changes in their environment than proactive individuals. Here, we report the characterization of personality profiles in mallards over a period of 8 months, as well as their reactions towards a spatial-learning task. Mallards' exploration scores were repeatable both in novel environment and in novel object tests. Even though they did not differ in their baseline cortisol levels, fast-exploring birds had lower cortisol levels 30 min after the occurrence of a stressor than slow-exploring birds. Irrespective of their personality, all our birds successfully learned to find a food location within a maze. Yet, fast-exploring individuals took longer to accomplish the task, potentially because they habituated faster to stress and could engage earlier in other activities within the maze. Our results contrast with recent views of the respective consequences of being reactive or proactive. They thus highlight the importance of considering the habituation to stress when investigating the relative advantages of the reactive e proactive continuum, as well as taking into account the personality bias when conducting cognitive experiments.