Why in earth? Dustbathing behaviour in jungle and domestic fowl reviewed from a Tinbergian and animal welfare perspective

The majority of studies of dustbathing behaviour address the question of causation. Dustbathing shows a clear diurnal rhythm and under unrestricted conditions, hens dustbathe about every 2 days. Birds deprived of litter show a rebound in dustbathing behaviour when litter is again made available, suggesting an increase in motivation after deprivation and so an influence of internal factors With respect to external factors, it has long been believed that dustbathing is socially facilitated, but this has been questioned in recent studies. The presence of a suitable substrate is an important stimulus for eliciting dustbathing, and hens seem to prefer substrates with a fine structure such as sand and peat. Dustbathing is further increased if the substrate is combined with light and heat. The question of whether or not hens are motivated to dustbathe has important consequences for bird welfare in commercial housing systems, but motivational studies give somewhat conflicting evidence. In the final part of this review, both normal litter dustbathing and 'sham' dustbathing in the absence of litter are discussed from a welfare perspective.