Influence of quantity of litter on nest box selection and nesting behaviour of domestic hens

1. Twenty two hens (Gallus gallus domesticus) were given a free choice, for egg laying, between 4 nest boxes containing different quantities of wood shavings (litter): 3180 cm3 (large), 1060 cm3 (medium), 350 cm3 (small) and none (zero). 2. There was considerable individual variation in the quantity of litter selected for egg laying, but 17 hens laid 50% or more of their eggs in a single litter quantity. Hens selected the large quantity in preference to the small and zero. More searching, nest selection and nesting behaviours tended to be directed to the boxes with the largest quantities and also to the quantities that the hens finally selected for egg laying. 3. In a second experiment, the hens from experiment 1 which showed a preference for litter, and a further 22 naïve hens were given a choice of three nest boxes containing no litter and one containing one of 6 quantities. Over 30 trials there were 5 replicates using each of the three quantities used in experiment 1 plus 115 cm3, 40 cm3 and 10 cm3. 4. There was a wide range in the proportion of trials in which hens selected litter; for experienced hens the range was 0.43 to 0.97, but only two naïve hens were within this range, all others being between 0 and 0.43. 5. The pattern of choosing litter quantities was comparable but at different levels of preference in experienced and naïve hens and a contour map was derived enabling predictions to be made of the probability of a particular quantity being chosen. 6. The variability of individual responses suggest that no single type of nest box system can cater for the requirements of all hens.