Herding and snaking by the harem stallion in domestic herds.

This study investigates the herding behavior of stallions in domestic horse herds. The factors that induce such behavior and its extent were examined through experiments with four herds, each consisting of a stallion and six mares.

Study Design and Methodology

• The study utilized four herds of pony mares. Each herd comprised of a stallion and six mares. The researchers decided to use four successive treatments to stimulate various scenarios. These were: six mares alone, the introduction of the stallion, the addition of two new mares, and moving the entire herd to a new pasture.
• A new treatment was started every 7 days, with the behavior studied over 5 consecutive days (Days 1-5) for each treatment. Observations were made every 10 minutes during a 2-hour period each day.
• To quantify the extent of herding, the researchers measured the average distances between mares. The behavior of snaking, a specific type of herding where the stallion extends its head and neck and holds its ears back, was scored on a scale of 0 (nil) to 3 (maximal).

Key Findings

• When the mares were alone, the average distance amongst the original mares was 5.0 mare lengths. This distance reduced significantly (P < 0.05) to 1.9 mare lengths when the stallion was introduced to the herd.
• In an already formed stallion/mare herd, the distance between the original mares was 3.8 mare lengths; this reduced when the herd was moved to a new pasture, similar to the effect seen with the introduction of the stallion. This suggests that both the addition of the stallion and the change of environment induce herding behavior.
• Scores for snaking, as well as the extent of herding, were highest (P < 0.05) on Day 1 when the stallion was added or the stallion/mare herd was moved to a new pasture. In contrast, herding and snaking decreased significantly (P < 0.05) by Day 2 and occurred less frequently on Days 3-5.
• The introduction of two new mares to the herd did not lead to an increase in the herding of the original mares. However, these new additions kept greater distances from the existing mares, ranging from 8-12 mare lengths. This was mainly due to the stallion chasing the new mares. By Day 4, the distances between the new mares and the original mares were no different (P > 0.05) from the distances among the original mares.

Conclusion

• This study sheds light on the dynamics within domestic horse herds, particularly the role of the stallion in herding and adjusting mare distances. The stallion’s presence, moving the herd to a new pasture, and the introduction of new mares all impact the herd’s dynamics profoundly.