Wintertime use of natural versus artificial shelter by cattle in nature reserves in temperate areas

The current study contributes scientific observation to the ongoing debate about whether and when artificial shelter (man-made), in addition to natural shelter (vegetation), should be provided to cattle grazing in nature reserves during temperate winters. In several year-round grazing projects in Belgium, we have investigated the effect of winter climatic conditions on cattle's use of natural versus artificial shelter. In eight nature reserves with varying amount and spatial distribution of natural shelter and an artificial shelter, GPS were used collars to monitor terrain use during one, two or three winters (per 30 min, 24 h per day). Cattle location data were related to instantaneous open-field measurements of the Comprehensive Climatic Index (CCI). In addition, the effects of the time of day (day-time versus night-time) and the amount of natural shelter and its spatial distribution on these relationships were investigated. In most nature reserves, cattle increasingly avoided open area and sought shelter at CCI values <0 °C. The strength of the effect, and whether cattle used natural or artificial shelter differed between day-time and night-time and between reserves, and was partially explained by the amount of natural shelter and its spatial distribution across the reserve. Although artificial shelters with three closed walls provided better protection against cold (especially wind chill), cattle were more likely to use natural shelter as long as it was sufficiently available. Providing an artificial shelter in nature reserves appears to have added value for cattle's thermal comfort only when natural shelter is scarce.