The visual barriers affect the drills’ behaviour in many positive ways and appear to diminish the visitor effect in several behaviours of the drills at Parken Zoo as previous studies suggested. However, the negative welfare indicators social agonistic behaviour and visitor interaction were still affected by visitors after the installation of the visual barriers, implying that the drills still find visitors stressful and that further improvements on the observation area indoors should be considered for the welfare of the drills at Parken Zoo.

With outdoor-only access together with feeding enrichment, the drills showed to be more active, forage more, be less stressed and focus less on visitors compared to with an indoor/outdoor access without added feeding enrichment. This suggests that outdoor-only access and feeding enrichment would be a valid option during summer season for the drills at Parken Zoo for the benefit of their welfare.