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

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

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

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

• 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

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

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

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)

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)

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

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

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