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Grevy's Zebra (Equus grevyi) Fact Sheet: Behavior & Ecology

Activity Cycle

Active day and night

  • Spend about 50% of time grazing (Klingel 1990)
    • Horses in general spend about 7 hours out of 24 sleeping (Estes 1991)
  • Activity pattern (Churcher 1993)
    • Early morning: mixed herds of Grevy's and other species of grazing mammals go to water
    • Morning: graze away from water
    • Mid-day: rest in shade
    • Mid-afternoon: go to water
    • Overnight: graze away from water

Home Range

Individuals can be highly mobile (from Moehlman et al. 2008)

  • Cover large distances in search of water
    • May travel > 80 km (50 mi)
  • Non-territorial individuals occupy a home range up to 10,000 sq km (3,861 sq mi)
    • 2 to 12 km sq (0.8-4.6 sq mi) for breeding males

Social Groups

Non-social (from Klingel 1974)

  • No permanent social bonds between adults
    • No herd system
    • Females and males without territories may form temporary grazing groups
      • Groups have no leaders; when walking any animal may lead
  • Mothers and young form temporary social units
    • Females with young may form nursery groups of up to 50 individuals
    • Females move freely in or out of nursery groups
    • Female groups are the result of ecological conditions and a female's reproductive condition
  • Territorial mating system
    • Only territorial males mate with females
    • Mating occurs only when environmental conditions are good
      • Similar to social system of the African Wild Ass (E. africanus); stallions do not keep a herd
      • Contrasts with Plains and Mountain Zebras that live either in family groups or stallion groups

Social hierarchy

  • Hierarchy only apparent when individuals are within a male's territory
    • Territorial males dominate females, but only while in their territories
    • When walking (outside a territory), any one member, whether male or female, may lead
  • Mutual grooming is not common
    • Behavior occurs less often than in other equid species

Territorial Behavior

Territorial Behavior

  • Breeding males occupy large, year-round territories
    • May keep their territories as long as 7 years
      • Neither body size nor territory size correlate with male reproductive success
    • Stallions may leave territories during dry season to find water; return in no more than a few weeks.
    • Males with a territory will tolerate other males in their space until an estrus female appears; visiting male then evicted
      • Transient males are typically young and move through territories while searching for food or water
  • Males advertise to claim territory
    • Scent marking
      • Males urinate and deficate on dung piles
    • Vocalization
      • Males bray
        • Bray sounds like "a hippo's grunt combined with a donkey's wheeze" (Estes 1991)
    • Boundaries are to orient the owner, not to keep out other males

Aggression

Female aggression

  • Aggressive when foal is very young
    • Females act aggressively towards all other zebras during first days of her foal's life
    • After foal imprints, she allows others to approach
  • Typically more aggressive towards other females than are Burchell's Zebras

Forms of aggression

  • Kick out the hindlimbs (together) in defense
    • Female stands with back toward attacker
  • Fighting behavior
    • Running, circling, neck-wrestling, biting and kicking
    • Rarely leads to serious injuries

Social Interactions

Play

  • Common among foals
  • Forms of play
    • Run, jump, butt, and chase one another; may even interact with other species
    • Male foals have mock fights

Communication

Visual Signs/Displays      

  • Wide repertoire of facial expressions, as in all horses
  • Territorial Grevy's male signaling dominance
    • Proud posture with arched neck and high stepping gait
    • Head, neck, and ears forward to meet a challenger
    • Ears flattened, head raise, teeth bared as a threat
    • May flail with forelegs and bite when attacking
  • Non-territorial male signaling submission
    • Extended tail, lowered head; nuzzle dominant animal in chest or groin
  • Female when threatened
    • Turns back to threat, one hindleg raised (ready to kick)
  • Both sexes when about to threaten
    • Swish tail rapidly
    • Foal draws close to its mother if she gives this signal
  • Resting heads on a partner's rump
  • Female when ready to mate
    • Gives open-mouthed "smile"

Vocalization (Estes 1991)

Grevy's Zebra audio, provided by Volodins Bioacoustic Group (2010).

  • Species of horses all share about 5 primary calls
    • 2 alarm calls - loud snort, quiet gasp i-hah
    • Short squeal when kicked or bitten, and in greeting
    • Drawn out squeal when injured
    • Blowing with loose lips when content
  • Contact calls differ according to different equid species
    • Grevy's males (and wild asses) bray to announce territory boundaries, to repel another male, or to drive a female
    • Horses whinny
    • Plains Zebras bark

Olfaction/Scent Marking

  •  Males mark territorial boundaries with urine and dung piles (Klingel 1974)
    • Dung piles may reach height of 40 cm (16 in)
  • Greeting ceremonies, nose to nose, and nose to rear (Estes 1991)

Locomotion

Quadrupedal

  • Walk, trot, and gallop (Estes 1991)
    • Gallop or trot with heads-up gait (Plains Zebras canter or gallop with heads much lower) (Churcher 1993)
  • Speed
    • Can gallop at 55 km per hour (34 mph)

Interspecies Interactions

Predators

  • Targeted by large carnivores
    • Lions
    • Also leopards, spotted hyaenas, hunting dogs, and cheetah

Share habitat with the plans zebra (E. quagga burchelli)

  • Species occupy many of the same habitats in northern Kenya (Kenya's National Grevy's Zebra Task Force 2008)
    • Species form mixed herds, often on edge of range
    • Interbreeding may occur (Groves 1974)
    • Grevy's Zebras extended their range to include areas once occupied by Burchell's Zebras alone

Associate with other ungulates

  • Form mixed species herds with wildebeest, beisa oryx, waterbucks, kudu, eland, and giraffe
    • Horned species larger than zebras are dominant when Grevy's at water holes in mixed herds (Kingdon 1979)
  • Grevy's may obtain some protection from predators as a result of this association

Grevy's Zebra

two Grevy Zebra

Image credit: © San Diego Zoo Wildlife Alliance. All rights reserved.

Page Citations

Churcher (1993)
Estes (1991)
Kingdon (1979)
Klingel (1974, 1990)
Groves (1974)
MacClintock (1976)
Moehlman et al (2008)

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