Horse Behavior

1. Horse Behavior Moira Ilg ERS 697 13-April-2004

2. Outline • Introduction and General Background • Social Status or Ranking • Foal and Mare Behavior • Stallion Behavior • Grazing Behavior • Conclusions and Possible Implications

3. General Background • Factors that influence dominance relationships • Body size • Physical condition • Age • Older the more dominant • Sex • Previous agonistic encounters • Group size • Dominance hierarchy of parents

4. Background continued • Band structure • Single adult male • Adult females and their offspring • Normally stable • Changes are normally juvenile males and females • Juvenile males may remain solitary for months or years • Juvenile females normally bands • A well defined hierarchy is present during grazing and will persist if they are provided with food

5. General Background • Behaviors • Threatening Behavior • Maybe widespread or may have a few favorites to pick on • Is often one sided • If there is a “winner”, they move up in rank

6. Behaviors • Grooming • Normally groom with two or three individuals that are similar in rank and age

7. Behaviors continued • Play • Important for social development of young • Most common within in peer groups • Submissive • Often a response to threatening behavior

8. Social Status or Ranking • Top ranking individual • Large number of threats • Distributed widely across the herd • Often don’t have “friends” • Stallion • Is often times the only breeding male • Mare • Often decreases aggressions as rank becomes higher

9. Social Status or Ranking • Friends • Normally close in age and social status • Mares may bond more closely with those that are related to them • It is important account for “friendships” when assessing the distribution of threats

10. Social Status or Ranking • Tend to be selective about who they interact with • Animals tend to spend the most time near individuals that have the same rank or age or both • Top ranking animals are seldom seen alone or in a small group • Elders are less social than the young • Often have fewer interactions with younger subordinate mares

11. Social Status or Ranking • May recognize individuals that they have competed with • Leading to fewer competitions in older animals

12. Theories of the evolution of bonds • Evolved between mares and stallion in a band because of pressure from predators that hunted cooperatively • Protect mares against harassment from other stallions and reduce inter-mare aggression

13. Mares • Acts of aggression is most common with mares that do not have foals • The least amount of aggression is seen between mares that have foals • Protection of foals

14. Mares • Intermediate aggression is seen between mares that have foals and those that do not • Young mares are much more aggressive than older mares when foals were less than a week old

15. Mares continued • Older mares have fewer encounters of aggression • Number of acts of aggression decrease as the mare becomes older • Aggression frequencies increase in May (foaling season) • Frequencies of aggression increase significantly the closer the mare is to parturition

16. The Advantage of Being A Dominant Mare • Receive less aggression • Access to shade on hot sunny or rainy days to rest • Increased access to feed • Supermare • May suppress conception, induce abortions, or harass or kill offspring of subordinate mares • However, dominant mares may not live as long • They have increased amount of stress and a increased amount of cortisol

17. The Disadvantages of Being A Subordinate Mare • Increased acts of aggression • Denied access to shady areas • Give birth to fewer or less fit foals • Denied access to food • Decreased growth rate

18. Foals • Foals will often play with foals of their dam’s friends • Also like to associate with foals of the same gender

19. Foals • In the case of fillies they most often will have a similar rank to their dam • Dams may assist their foals in agonistic encounters • Foal-mare association • Genetics

20. Stallion Behavior • Some bands will have multiple stallions • The subordinate stallions are more likely to help defend the band than the dominant stallion • However these stallions are forced to stay on the periphery of the group by the dominant stallion

21. Grazing Behavior • The time spent grazing is dependent on the intake of the grazer • Daily intake is determined by • Time spent foraging • Varies from a few minutes to 13hrs and 25 min • Bite rate • Bite size • Are selective when quantity and quality of forage is high • When drops below a threshold level they become less selective

22. Grazing Behavior • Foraging time increases for mares in the summer months • Major feeding bouts after dawn and before dusk • Feed mainly during the day except for summer months when there is a midday lull

23. Grazing Behavior • Often forage from plant communities that are continuous with patches of more desirable plants • May use spatial memory to find those plants that are the most desirable • Study by Edwards et al., 1996

24. Grazing Behavior • Most large herbivores rest in the areas that they graze • Some herds have been shown to travel over 1 kilometer to high ground, saltflats with low plant cover, or denuded vegetation • Yet when they arrive they show signs of extreme discomfort

25. Grazing Behavior • So why travel all that distance? • Higher altitude cooler temps? • Unlikely, cooler temps are more likely to be found in shady areas rather than bare ground • Fewer biting flies? • Probably, though the reasons are unclear • Most likely the flat, open areas are poor habitat for biting flies

26. Grazing Behavior • Is it really worth the effort? • They can lose up to 500cc of blood to biting flies a day • Biting flies are also the carriers of disease • Anthrax • Lethal arbovirsues • Horses actually spend less energy in the comfort movements

27. Grazing Preferences • Preferences • Prefer gentler slopes • Mesic grasslands • Avoid • Steep slopes • Drier grasslands • Large tracks of forests

28. Home Range • Home range varies in size in relation to the band size • Home ranges overlap • Groups can move seasonally • Home range cores become larger during winter months than in summer months • Change elevations for foaling and mating

29. Methods • Focal animal • Focal groups

30. Problems • In feral herds it is often times difficult to identify individuals • Identify distinctive individuals • Markings • Colorations • Sex • Location • Counting by helicopter

31. Conclusion • Horses are for the most part herd animals and they move as a herd, but can be influenced by individualistic behaviors • There are reasons and patterns in their movements that can be predicted when their behavior is understood

32. Possible Implications • Understanding behavior can allow • Better prediction of movements • Understanding habitat choice • Better herd management

33. Questions Questions?