Behavior of horses on pasture in relation to weather and shelter-A field study in a temperate climate

The behavior and use of shelter by 426 domestic horses on 166 pastures was studied in relation to weather conditions in a temperate climate. The pastures varied in availability and type of shelter (artificial and/or natural). Observations were carried out once per pasture, but to increase the number of replicates in some classes of weather conditions, observations on some horses were repeated. Horses were observed without interfering with their everyday routine. At each sampling time, weather conditions, such as ambient temperature, humidity, wind speed, precipitation, and cloud cover were noted. A 5-point ordinal scale was used to score the horses' behavioral response to flies, defined as insect-avoiding comfort behavior. The mean use of the artificial shelters was 37.6% per observation moment. When dry air temperature was lower than 7.1°C or higher than 25.2°C, a 2-degree fit showed a higher artificial (man-made) shelter use. This is explained by the dampening effect of the artificial shelters on ambient temperature during cold circumstances, the temperature outside artificial shelter was lower than inside, whereas during warm circumstances temperature outside was higher. Regardless of temperature, but when wind speed was >2.8 m/s, shelter use was higher on rainy days than on dry days. Sheltering was also observed inside the thermo-neutral zone of horses (41.0% of the total observation time). This behavior could be explained by other micro-environment related aspects, such as insect harassment. These results suggest that having access to shelter seems important for horses.