Horse Behavior

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Horse Behavior

• Moira Ilg
• ERS 697
• 13-April-2004

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Outline

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

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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

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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

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Behaviors

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

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Behaviors continued

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

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Social Status or Ranking

• Top ranking individual
• Large number of threats
• Distributed widely across the herd
• Often dont have friends
• Stallion
• Is often times the only breeding male
• Mare
• Often decreases aggressions as rank becomes higher

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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

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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

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Social Status or Ranking

• May recognize individuals that they have competed
  with
• Leading to fewer competitions in older animals

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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

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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

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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

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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

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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

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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

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Foals

• Foals will often play with foals of their dams
  friends
• Also like to associate with foals of the same
  gender

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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

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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

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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

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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

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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

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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

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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

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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

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Grazing Preferences

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

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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

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Methods

• Focal animal
• Focal groups

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Problems

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

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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

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Possible Implications

• Understanding behavior can allow
• Better prediction of movements
• Understanding habitat choice
• Better herd management

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Questions
Questions?