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A 'plague' of rats in Amboseli
If it's not one thing, it's another.
The ecosystem constantly has its knocks: too little rain, elephants getting speared, too many permanent settlements crowding the park boundary ... This dry season it's also rats!
For the past two months, elephant researchers working staying at ERC (Elephant Research Camp) have noticed increasing numbers of small, brownish rats scurrying in and out of the long grass onto the mowed pathways between the tents.
They were skittish at first but are now nearly as confiding as the camp's birdlife and zebras. At any one time there may be a dozen grazing busily within twenty feet of the researchers' breakfast table. They scuttle into the long grass at the base of the palms as you walk by, and reemerge a few seconds later in your wake barely missing a bite.
Jonathan Kingdon's Field Guide to African Mammals confirms that our little visitors are one of the several species of the genus Arvicanthis, with the unglamorous English name, 'Unstriped grass rats'. They are diurnal grass-eaters. Kingdon, in his encyclopaedic East African Mammals: an Atlas of Evolution reckons that they are most active in the early afternoon, during the 'siesta' lull in avian and mammalian predator activity. 'Our' rats are probably benefiting from their proximity to humans that keeps predators away, since they seem to be busy all day.
Although Kingdon reports that several litters may be born during the wet season, 'our' rats have a number of young, probably only a few weeks old, likely to have been conceived during the earlier part of this dry period that looks like it will be a long, bad one. The heavy rains last November and December (60% of the average annual total) probably charged the water table sufficiently to keep the grass supply robust in Ol Tukai Orok (the area around ERC) till today.
One of the adult males has a conspicuous white blaze on his back. We call him 'White Fang'; he seems to be dominant to the others.
The Arvicanthis are doing well, eating like mad: we can almost discern their grazing impact along our pathways. One of our Maasai staff, Saruni, tells us that his people are very unhappy about the toll the hoards of little grazers are having on the dry-season diminishing grasslands outside the park: they are competing successfully with the cattle!
At least they can't blame the elephants for this one!