Any­thing but or­di­nary

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ou could set your cal­en­dar to the so­cial be­hav­iour of im­palas. Ev­ery year in Fe­bru­ary, adult im­pala males (four years and older) start split­ting off from their bach­e­lor herds to form tem­po­rary ter­ri­to­ries of their own – a process that lasts un­til the end of April. They mark their ter­ri­tory by defe­cat­ing in mid­dens, past­ing gland se­cre­tions from their fore­heads and by their dis­tinc­tive roars and coughs that can be heard through­out the night. (I’ve of­ten had to con­vince sa­fari guests that the “roar” they’re hear­ing is ac­tu­ally a be­nign an­te­lope and not some fierce preda­tor!) Fe­male herds are non-ter­ri­to­rial and move freely though males’ ter­ri­to­ries. When a fe­male herd ar­rives, the males do their ut­most to keep them in the area while at­tempt­ing to mate at the same time. This is tir­ing work and the dom­i­nant male loses con­di­tion quickly. This is when other males might try to oust the ter­ri­tory holder – an ousted male will join a bach­e­lor group con­sist­ing of non-breed­ing males. Af­ter the rut, the ter­ri­to­rial urge di­min­ishes and the males re­join their bach­e­lor groups, where more eyes and ears of­fer bet­ter pro­tec­tion against preda­tors. The fe­males give birth from Novem­ber, af­ter a sev­en­month ges­ta­tion pe­riod. It’s a com­mon mis­con­cep­tion that fe­males can hold their un­born young in­side un­til con­di­tions are suit­able. No an­i­mal has con­trol over the growth rate of a foe­tus. To­wards the end of Novem­ber and De­cem­ber, the bush comes alive as lambs are born within weeks of one another. This cre­ates a feast for preda­tors, but the mar­ket is flooded to such an ex­tent that enough lambs are able to reach sub-adult­hood and avoid be­com­ing prey. Preda­tors like jack­als and lions feast on im­pala. As a re­sult, the an­te­lope have well-de­vel­oped es­cape mea­sures in place. In­di­vid­u­als warn the herd when a threat is nearby. Should some­thing spook the herd, the var­i­ous an­i­mals will scat­ter in dif­fer­ent di­rec­tions to con­fuse the preda­tors. It is be­lieved that a gland on the im­pala’s hind leg (it looks like a black spot) re­leases a scent that helps the herd re­group af­ter an at­tack. So next time you pass yet another herd of im­pala – some­times called the McDon­alds of the Bush – take a mo­ment to mar­vel at all the fea­tures that make them so suc­cess­ful.

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