Grevy’s & Plains Zebra

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Grevy’s zebra (Equus grevyi) is the largest living equid, built tall and sleek like a stallion. They are differentiated from the sympatric plains zebra (Equus quagga) by having thinner stripes and lack of a thick black strip along the belly. This species is classified as endangered by the IUCN, experiencing one of the greatest population declines of African megafauna in the past few decades— over 50% to less than 2,500 individuals left in the world. Their distribution is restricted to southern Ethiopia, and northern and central Kenya. Habitat loss, overgrazing by livestock, and poaching are three major threats to the Grevy’s zebra, pushing them south, and they have a long gestation time (over one year) making population growth rates slow. Nevertheless, in pretected areas in Laikipia populations of Grevy’s zebra have been steadily increasing.

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A Grevy’s zebra mother and her adorable foal— round ears at the ready and a furry crest spanning from its mohawk tuft to the tip of its tail. Herds of Grevy’s zebra tend to be more dispersed spatially than plains zebra, making them less of a cohesive unit and possibly at a higher risk of predation. Especially in areas where lion population densities are high, it might be more likely for lions to have their eye on a straggler Grevy’s. Once I saw two lionesses eating a female Grevy’s zebra, and another time a big male carcass lay eviscerated along the side of the road… every time I mentioned the kills to my friends, the reaction was usually: “why did they have to prey on the endangered one??” However, a few radiotelemetry studies suggest that lions do not preferentially prey on Grevy’s zebra, and the threat from natural predation on Grevy’s zebra populations is dwarfed by the issues of competition with and displacement by livestock.

Two playful juveniles and their “mohawks”
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Although common at Mpala, it is always wonderful to watch giraffes stripping leaves and zebras pruning grasses like a lawnmower. Just behind this cohort, 30-40 giraffes stretched along over a hundred meters, mostly visible as heads and necks popping over the trees.

As they graze, reticulated giraffes and plains zebra swat off pesky flies using their coarse black hairy tails. The tails constantly move back and forth for hours on end, so I’ve often wondered if they have robust tail musculature to keep them going. I certainly can’t move my arm in circles for such an extended period of time. The tail movement is so rhythmic and regular that I think the motion works similarly to the centripetal force in a pendulum— as the tail falls from one side, inertia will cause it to swing down and up over to the other side in a circular path, and probably not require so much muscle output. But then again, thinking back to my cat at home who continuously moves her tail in all directions, maybe animals just have really strong tails.

All photographs in this post are in situ [1]

Plains zebra (Equus quagga) on a cloudy day, foraging on grasses and low-lying vegetation while wattled starlings (Creatophora cinerea) drink nectar from the flowers; see photobomb in the left bottom corner.
Grevy’s zebra, camouflaged in the dry season
Plains zebra, near Mount Kenya
Plains zebra, near Mount Kenya
Plains zebra foal, near Mount Kenya
Plains zebra, near mount Kenya

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