Abstract

Cognitive bias tasks have been used effectively to assess the welfare of animals in a variety of captive settings. However, they have not yet been used to assess the welfare of wild animals, which is increasingly influenced by human activity. Therefore, I aimed to develop a cognitive bias task for use in the wild. I adapted the standard judgement bias paradigm to test free living woodland birds, with the prediction that birds in more fear-inducing habitats would show a cognitive bias by making more pessimistic judgements of an ambiguous stimulus. To assess the influence of a naturally variable environment on wild birds’ welfare, an area of woodland was mapped in order to identify areas expected to induce a high level of fear (further away from cover, closer to paths) and areas expected to induce a lower level of fear (close to cover, further away from paths and open areas). Free standing bird feeders were placed at 15 ‘high-fear’ and 15 ‘low-fear’ locations, as inferred from the map. At the feeders, a foraging-based judgement bias task was presented; the stimuli were artificial dough ‘worms’ of different colours – red and yellow. Following habituation, the red worms were made unpalatable by coating them with a Bitrex (denatonium benzoate) solution, and the birds’ learning of the colour discrimination was measured by recording the removal of worms over time. Finally, intermediate orange worms were introduced, to assess the birds’ judgement of an ambiguous stimulus. Location had a significant effect on the number of worms takenthroughout the stages of the task, with consistently more being taken from the low-fear feeders. This difference in foraging behaviour suggests that the habitat map successfully identified locations that induced different affective states for birds, further evidencing the impact of understory cover and human disturbance on birds’ welfare. However, discrimination training was unsuccessful as the colour of the worms did not significantly affect how many were taken, potentially due to insufficient training presentations, or Bitrex not being an adequate deterrent. Therefore, it cannot be confirmed that the birds perceived the intermediate stimulus as ambiguous. This study highlights the potential advantages and challenges associated with using cognitive measures in the wild. Anthropogenic activity is increasingly impacting the welfare of wild animals, therefore, further developments of alternative methods for assessing the welfare of wild animals should be considered a research priority.