Zebra’s are one of the most iconic of all of Africa's grazing animals. The most common species is the plains zebra, which roams grasslands and woodland of eastern and southern Africa. The Grevy’s zebra can be found in dry, semi-desert areas of Kenya and Ethiopia, and the mountain zebra lives in mountainous and hilly habitats in Namibia, Angola and South Africa. They are recognisable across the world for their striped coats which come in different patterns, unique to each individual.
The zebra’s stripes are an effective control mechanism used to reduce the number of insect bites. Zebra’s receive less bites than animals with a single fur colour as biting insects are more attracted to large dark objects in their environment but less to dark broken patterns such as the stripes of a zebra. The effectiveness of the stripes is also used by tribal people living in similar regions, painting their bodies with stripes to also reduce the number of bites they receive.
As the stripes provide an individual marker for each zebra, they also play a key role in individual recognition. Zebra’s are social animals that live together in small harems to large herds and they are able to recognise individuals and remember the relationships they have had with those individuals over time. This is particularly important for social animals which live in such large numbers.
Within a herd, zebras tend to stay together in smaller family groups made up of a male, several females and their ‘foals’ and they communicate with each other through facial expressions, ear positioning and sounds. They make loud braying or barking sounds and soft snorting sounds. Their ear positioning, how wide open their eyes are, and whether they show their teeth all send a signal that is understood by other members of their social group.
Each year, zebras are part of one of the most spectacular sights in the animal kingdom, as thousands of animals, including zebras, wildebeests and gazelles, migrate in turn with the seasons between foraging grounds, in search of sufficient and highly nutritious forage. For many years it had been assumed that these migrations were based on the availability of the resources, but recent research has shown the dominating factor in such movements may in fact be based on an animal's memory, combined with food availability. With zebras using their memory of previous locations, where foraging conditions were best in the past, as the primary driver over the environmental conditions to guide their migrations.
To determine this researchers modelled migration routes of zebras using computer simulations. Zebras migrate around 250 kilometres from the Okavango Delta, Botswana to the Makgadikgadi grasslands in November. They tested two mechanisms which can influence the direction. Simulated zebras could use perception and sense, for example, the vegetation in their current surroundings. Alternatively, zebras could use memory, i.e. information from previous migrations, to forecast where to go.
The researchers compared the simulated tracks with real-life tracks from GPS-tagged zebras. Memory using past average conditions was able to predict the migration destination of the model. However perception is still important and studies have shown that perception of current local conditions plays a key role on the timing and speed of the zebra migration, but it appears that these may be less important for zebras in terms of direction.
This use of memory as a key driver means that they could be far more inflexible than previously thought. Migration routes of zebras are threatened by climate change and land use changes, yet these routes must remain open for the survival of the species in the long term.
Threats
Zebras have been hunted for their meat and their skins and continue to suffer due to habitat destruction. Grévy's zebra and the mountain zebra are now both endangered species due to such persecution. The Cape mountain zebra was hunted to near extinction, with less than 100 individuals by the 1930s. The population has since increased to about 700 due to conservation efforts and effective habitat protection.
Hunting and competition from livestock have greatly decreased the Grevy’s zebra population. Because of the population's small size, environmental hazards, such as drought, are capable of affecting the entire species. Plains zebras are much more numerous and have a healthy population. Nevertheless, they too have been reduced by hunting and loss of habitat to farming and human encroachment.
For details of zebra conservation measures see;
African Wildlife Foundation; https://www.awf.org/projects/grevys-zebra-protection
Grevy’s Zebra Trust; http://www.grevyszebratrust.org/
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