Moroki, Y. 2019. Sham dustbathing in cages by subordinate hens is increased by a partition providing isolation. Applied Animal Behaviour Science 210, 68-72.

Subordinate hens express less sham dustbathing in cages than higher ranked hens, their bouts often being disturbed by a higher ranked hen. However, seeing conspecifics seems to encourage this behaviour by hens. So to avoid being disturbed, a partition between hens in a cage may facilitate sham dustbathing by subordinates. Therefore, one aim of this experiment was to test the effects of two types of partition, transparent (wire) and opaque (cardboard). The other aim was to test the response of birds of different rank. Experiments began when the hens were 35 weeks of age in non-furnished experimental cages, after determination of rank in groups of four (low (two birds), ‘middle’ or high). Thirty two hens were divided into eight pairs for each of two types: low and middle or low and high ranks. These were used first in wire partition experiments, then in cardboard partition experiments. For each experiment, four pairs were tested with a partition in a cage for two days, while the other four were used as controls, then the treatments were switched so that all pairs experienced both. Subordinate hens performed fewer sham dustbathing bouts than higher ranked hens in controls for both wire and cardboard experiments. However, when there was a wire partition between a low and a middle ranked hens, total time and percentage of hens sham dustbathing increased in subordinates compared to controls (P < 0.05), while middle ranked hens did not show a difference. When there was a wire partition between a low and a high ranked hens, total time spent sham dustbathing and number of bill rakes increased in subordinates compared to controls (P < 0.05), while high ranked hens did not show a difference. With a cardboard partition, the number of hens sham dustbathing and total sham dustbathing bouts increased in subordinate hens compared to controls (P < 0.05), whereas bouts decreased in middle ranked hens. With a partition, termination of sham dustbathing by interruption from another hen decreased by half in subordinate hens. These results indicate that a partition between hens, whether subordinate hens could see the other bird or not, allowed sham dustbathing to start with little or no disturbance from higher ranked hens. However, it may be also important for some hens to see conspecifics to start and to continue this behaviour. Therefore, a partition that prevents agonistic behaviour and allows performance of other behaviours may facilitate better environment and welfare for hens.