Damage to round bale silage caused by sika deer ( Cervus nippon) in central Japan.

Round bale silage is a widely used forage production system in Japan. In recent years, several suspected instances of damage to bales of round bale silage by sika deer were reported on a dairy farm in central Japan. We sought to confirm whether this damage was indeed caused by sika deer, and if so, when and how they caused the damage. We also analyzed the effects of possible covariates on seasonal and spatial variances in the incidence of the observed damage. Continuous monitoring using camera traps revealed that sika deer were responsible for the damage to the bales of round bale silage. The sika deer were observed to nibble at the surface of the bales of round bale silage after puncturing the plastic film used to promote anaerobic digestion of the silage. Several sika deer were responsible for damaging the bales of round bale silage, and the incidence of damage to the bales increased as snow cover increased in winter. Further, the incidence of damage to the bales of round bale silage was greatest farthest away from the center of the farm facilities, and farthest inside the wildlife protection area, which covered a large proportion of the farm. The findings clarified the extent of damage caused by sika deer to bales of round bale silage, and illustrated the need to prevent such damage throughout the country. [ABSTRACT FROM AUTHOR]