Have you ever had a chance to quietly watch a herd of horses for a long time? What do you see and notice about how they get along?
As scientists discover more about the way a horse’s social life affects their behaviour and possibly training, researchers find themselves in need of a reliable, efficient way to measure social hierarchy.
Within any herd or group of horses there is an order of dominance, the social hierarchy; one horse is at the top and another is at the bottom with all the others ordered in between. The horses establish a “pecking order” for the purpose of determining which herd member directs the behavior of others, eats and drinks first, and so on.
Observing how horses interact with each other in the field has historically been the most reliable method, Line Peerstrup Ahrendt, PhD, researcher in the department of animal health and bioscience at Aarhus University, said during a presentation at an International Society for Equitation Science conference.
‘But you can’t just watch horses for a half an hour to see whom assumes role of “leader.” Social hierarchy among horses is complex; it’s not just about finding a single herd leader,’ she said.
And that’s why in order to get accurate results, field observation of a group of horses usually requires at least 15 hours over a five-day period, sitting in the grass with a clipboard, jotting down every detail of horses’ interactions with each other. And often, horses are so used to their hierarchy that their social interactions don’t give obvious clues, Ahrendt added.
1. Assuming the researchers spend the same number of observation hours each of the five days, how many hours a day are they in the field?
To improve social hierarchy studies, Ahrendt and her colleagues have recently developed a more efficient system called the “limited resource test.” By placing three bins of food in the group’s pasture, scientists can study the interactions among all the horses for as little as 80 minutes over a four-day period. And according to their research, the limited resource test is just as reliable as the much longer field observation method.
2. How much time do the researchers spend in the field with the new method?
3. How much less time are they in the field than with the first method?
Her study involved a comparison of both methods with the same group of horses: 25 Warmblood geldings age 2 to 3 years old. They had been pastured together in a 19-acre field for two months–long enough to establish their social hierarchy.
The researchers recorded 180 interactions during the five-day, 15-hour field test. They recorded 163 observations during the four-day, 80-minute limited resource test. Ratio calculations were made to determine the hierarchy in both tests.
4. How many minutes are there in 15 hours?
5. Now compare the number of interactions with the number of minutes from each test.
“The results showed a significant correlation between the hierarchical orders obtained by the two methods, suggesting that the less time-consuming limited resource test can provide the same information regarding hierarchy based on aggressive encounters as when determined by field observations,” she said.
“This is really good news for horses and their owners because this simpler, less expensive method means more research into social hierarchy, which is fundamental to understanding equine behavior,” Ahrendt said.
1. Assuming the researchers spend the same number of observation hours each of the five days, how many hours a day are they in the field?
Answer: 15 ÷ 5 = 3. The researchers spend 3 hours a day in the field.
2. How much time do the researchers spend in the field with the new method?
Answer: 80 minutes ÷ 4 = 20 minutes. The researchers spend 20 minutes a day in the field.
3. How much less time are they in the field than with the first method?
Answer: Step 1. 3 x 60 = 180. There are 180 minutes in three hours.
Step 2. 180 – 80 = 100. They are in the field 100 fewer minutes.
4. How many minutes are there in 15 hours?
Answer: 15 x 60 = 225. There are 225 minutes in 15 hours.
5. Now compare the number of interactions with the number of minutes from each test.
Answer: Method 1: 180 interactions were observed in 225 minutes.
Method 2: 163 interactions were observed in 80 minutes.
6. Write these results as a ratio.
Answer: Method 1: 180/225
Method 2: 163/80
Photos:
Horses On The Move by Linda Tanner; CC BY 2.0
Horses__dsc0149a by Singh; CC BY 2.0
Line of horses by Darryl Smith