Wednesday, February 23, 2011
Monday, February 21, 2011
Modern Threats to Zebra Habitat
A few decades ago, more than 15,000 Grevy’s zebra inhabited Africa. Today, fewer than 2,500 remain. The greatest threats facing the species today are habitat fragmentation and loss as more land is converted to agricultural use. Overgrazing by livestock is leading to significant environmental degradation - Grevy’s zebras compete with the ever-increasing livestock population and agricultural crops for water.
Getting a Head Count
Under the leadership of AWF research scientist Dr. Paul Muoria, AWF is working hard to better understand the Grevy’s zebras that live in Northern Kenya, specifically in the Samburu Heartland. With a clearer understanding of the Grevy’s population status and critical threats, AWF and its partners can develop effective conservation strategies.
Grevy's Zebra Conservation Project
Partnering with the Kenya Wildlife Service (KWS) and other conservation organizations, various community-based groups in Samburu and Isiolo districts of Kenya, AWF set out in 2002 to conduct population censuses on community lands and the protected areas of Samburu, Buffalo and Shaba National Reserves.
When AWF initiated this project, the aim was to contribute towards the conservation of viable population of the Grevy’s zebra in the Samburu landscape. To accomplish achieve this goal, AWF drew these long-term objectives and methods:
Monitoring Grevy’s zebra population size, structure and distribution:
Data on the population size, status and the spatial and temporal distribution of Grevy’s zebras is necessary for effective management and conservation of this endangered species. In early 2003, the research team designed census routes to cover the potential areas used by Grevy’s zebra. Each area is surveyed at least every two months. For each group of Grevy’s zebras encountered, the following information is recorded: their position using Global Positioning System (GPS), number and group composition, habitat and other large grazers in the vicinity.
Grevy's zebra are also monitored through the line transects method. This method involves setting transects along which observers have to walk while searching for and counting target species. Once the target species is encountered, one has to measure their distance from the transect center-line and their bearing from the observation site. The distances and numbers are converted into densities using a statistical software.
Monitoring and mitigating threats to Grevy’s zebra survival:
The team monitors zebra mortality, from disease, and anti-poaching activities. In 2005, AWF initiated a community-based scout’s program to monitor wildlife abundance, the poaching threat and human-wildlife activities. Since then, only two incidents of Grevy’s zebra poaching have been reported.
Implimentation of the National Grevy’s Zebra Conservation and Management Strategy:
AWF and the Kenya Wildlife Service (KWS) co-financed the development and production of a strategy document, which was officially launched in June 2008. AWF’s Director of Conservation Science Dr. Philip Muruthi is a member of the National Grevy’s Zebra Management Committee while Grevy’s Zebra Researcher Dr. Paul Muoria is a member of the National Grevy’s Zebra Technical Committee and Wamba Site Management Committee. AWF is now well-positioned to use its research findings to influence policy formulation in respect to the conservation of Grevy’s zebra.
Community awareness meetings:
AWF is working with local communities to raise awareness and construct strategies that benefit the local people and the Grevy's zebra.
Using GPS–GSM collars to Map Grevy’s movements in and around Buffalo Springs and Shaba National Reserves:
In 2010, five female Grevy’s zebra were fitted with GPS-GSM collars. The overall goal of collaring Grevy’s zebra was to investigate how Grevy’s zebra use the habitat in space and time.
See picture on right: KWS Vet Department personnel fit a collar on an adult female Grevy’s zebra in Buffalo Spring National Reserve.
Since its inception, AWF’s Grevy’s zebra research has made considerable progress in gaining a greater understanding of the population. Until AWF and its partners intensified their work on the Grevy's zebra over the last several years, there was little awareness about its conservation status at the local, national and international levels. Armed with data and information on the temporal and spatial distribution of Grevy’s zebras in the landscape, the AWF team is now working closely with local communities and authorities to secure key areas for Grevy’s zebra conservation.
Conservation of this species involves initiatives like exploring alternative land uses, forming participatory natural resource management plans and raising the legal status of Grevy’s zebras. Currently, the species’ only protection is through the 1977 hunting ban. If the ban were lifted, the species could be hunted at a fee because it is still classified as a game animal. AWF’s proposal to upgrade the Grevy’s zebra from “game animal” to “protected animal” under Kenyan law has in principle been accepted by KWS.
Hopes of a Bright Future for Grevy’s Zebra
While the Grevy’s zebra population is becoming more stable, the population has not recovered sufficiently enough to be removed from the list of Endangered Species. The Grevy's zebra must compete for limited forage and water resources with the pastoralists and their livestock. It must also move across the landscape as dictated by the seasonal distribution of water and pasture. Increasing human population and the resulting competition from alternative land uses continue to be a threat to corridors needed to ensure free movements of Grevy’s zebra and other wild animals.
But, AWF believes with diligence, the Grevy’s zebra population can rebound. Picture, above left: Community scouts being trained by KWS veterinary personnel in collecting samples.
AWF’s Grevy’s Zebra Research Project team is working fast and furiously to apply their census findings to the development of effective conservation efforts. AWF is working with reserves’ management and their rangers, who conduct regular patrols and are best placed to monitor the health of wild animal populations and their habitat in a sustainable way, to develop a Ranger Based Monitoring (RBM) system. Once piloted in Samburu National Reserve, the program will also be implemented in Shaba and Buffalo Springs National Reserves. AWF is also set to integrate ecological monitoring into its Grevy's study.
AWF will be working hard to ensure that these beautiful equids can roam freely along their migratory routes, can graze sufficiently and have access to critical water sources.
Zebras are herbivores, which means they eat only plants. They have very mobile lips which grip a tuft of grass while their front teeth cut it off. Their back teeth (molars) grind the grass.There is little nutrition in grass, and zebras are not ruminants like giraffe so they need to eat a lot in order to get enough nutrition. This means they graze for most of the day.
A mare gives birth to a foal about 12 months after mating with a male. For at least two days, the mother keeps other zebras away from her newborn foal so that they learn to recognize each other patterns. Foals have legs almost as long as an adult's so that one hour after birth it is able to run fast enough to keep up with the herd. Foals stay close to their mothers for protection. They suckle milk from their mothers.
Zebras have strong bodies and legs, small hooves, big ears and stiff manes that are striped. Zebras have a pattern of white and black stripes. There are small differences in how the different kinds of zebra look. Some kinds have white legs, some have brownish 'shadow stripes' in between the black and white stripes, some have narrow stripes close together, some have leg stripes all the way down to the hooves, some have them halfway down. The Grevy's zebras are the largest, with large, rounded ears.
No two zebras have the same pattern, just like human fingerprints. They can even have a different pattern on one side of their body to the other. We don't really know for sure why zebras have the patterns they do. One theory is that when a herd runs together a predator gets confused by the swirling black and white stripes. Another theory is that the air over the black stripes is warmer than the air over the white stripes, and so the warm and cool air swirl and fan the animal. This also creates a shimmer around the animal, making it harder for predators to see individuals.
Zebras are fast runners, and stay very alert all the time in case of danger. They kick hard with their hind legs. They have excellent eyesight, smell and hearing to help alert them to predators.
Most kinds of zebra live in families consisting of a stallion, 2-6 mares, and their foals. Large herds of zebra are usually made up of numerous families. Life is safer in a herd, with many animals alert to danger. If one member of the herd is in trouble, others will try to help. If one member is lost, all members rush around calling until it is found.
They have long jaws to help them hold big mouthfuls of food. Their eyes are located high on the head and at the side so that while they are grazing they can still look out for danger.
There are several species of zebras, which can be distinguished by their stripe patterns (123Spot 1999). Grevy’s Zebra (Equus grevyi) is larger than the plains zebra and has many more, narrower, black stripes. The Mountain zebra (Equus zebra) is smaller than the plains zebra. It has an unpatterned belly and a dewlap on its upper throat (Alden 1995). The plains zebra is the most common zebra, although one of its subspecies, the quagga (Equus quagga) is already extinct.
Zebras are equids, which means that they are medium-sized odd-toed ungulates. Their bodies are very well adapted for survival: long legs for quick and efficient movement; matched set of incisors for feeding on higher-fiber, tougher grasses; single stomach and hind-gut fermentation for quick digestion of high-fiber foods; hard hooves for long migrations (Moelhman 2003a).
image courtesy of Woodland Park Zoo
Plain zebras are found in eastern, southwestern, and southern Africa, with the largest populations in Tanzania and Kenya (Moelhman 2003a). Every rainy season, zebras lead a mass migration across the Serengeti. They travel through a variety of habitats, including Savannah, short grasslands, tall grasslands, and open woodland. They are dependent on water, and so must stay within 20 miles of water holes during the dry season (Estes 1991).