Research note: Shedding a light on dustbathing preferences - Do hens prefer bright or dark dustbathing areas?

Light intensity is an important factor in designing functional areas in poultry housing, as it influences behavioral activity. However, its influence on dustbathing behavior remains unclear. This study investigated whether laying hens prefer to dustbathe in brighter or darker areas, in combination with either a dark or light colored dustbathing substrate (i.e., peat or sand), using a preference test. Twenty-four hens, housed in pairs, were tested in three successive rounds (n = 8/ round) during which they were given a choice out of four different compartments containing sand at 5 lux, peat at 5 lux, sand at 100 lux, and peat at 100 lux. Dustbathing behavior and duration were recorded via video, and visits to the compartments were registered by RFID. Hens showed a clear preference for dustbathing in peat at 100 lux, as they performed more dust baths in this combination compared to sand at 100 lux, peat at 5 lux, and sand at 5 lux (P = 0.003, P = 0.002, P < 0.001, respectively). Hens visited the compartments with sand at 100 lux more often than those with sand at 5 lux (P = 0.02), while no other differences in visit frequency were found. Visit frequency substantially exceeded dustbathing events, suggesting that compartment visits may also reflect the motivation to explore or forage. Our findings provide a first indication that substrate preference and light intensity may interact to reinforce dustbathing behavior, which provides practical guidance for designing dustbathing areas in commercial housing systems.