"The Impala (Aepyceros melampus) is among the most numerous antelopes in Africa and among the least frequently accorded dedicated study by this author, who notes with some discomfort that his previous entries on the species amount to three sentences across two volumes. It is reddish-brown, white-bellied, horned in the male. It leaps. The author has written 'leaps' without further investigation and now proposes to investigate. The black tufted glands on the rear legs, which the author had attributed to colouration, are scent glands. This too requires revision."
He had been walking past them every morning for as long as he had been in Africa.
This was, when he considered it, quite a long time to walk past something. The impala appeared in his notes as background — waterhole edge, drainage line, open ground — the way a familiar piece of furniture appears in a room without being seen. He had written impala grazing, distance in the margin of other animals' entries. He had never opened a page and written impala at the top and begun.
He opened a page.
He wrote Impala at the top.
He looked at the herd at the waterhole's edge — perhaps forty animals, the females and young in the loose, watchful group, two males at the periphery, a bachelor group of six sulking along the drainage line in the manner of animals that have recently lost an argument and have not recovered their dignity.
He wrote: Abundant. Present. Previously noted only in margin. Beginning now.
The leaping started without warning.
One animal — a female near the waterhole's edge — launched herself vertically into the morning with the specific quality of something that has made a decision before the rest of its body has been informed. Three metres, approximately. Then forward — ten metres at least, the arc clean and committed. She landed, continued moving, leapt again. Then a second animal. Then six. The herd scattered in a pattern that had no obvious direction — some leaping, some running, some stopping, some leaping again — and the Colonel, who had been writing calmly, found himself holding his pencil without moving it.
He scanned for the predator.
There was no predator.
He wrote: Stotting behaviour. No threat visible. Searching.
He watched the leaps — the height of them, the explosive quality, the fact that the animals were announcing themselves at maximum visibility during what appeared to be an escape behaviour. He had written alarm signal and then stopped. An alarm signal that made you more visible seemed like the wrong kind of alarm signal. He crossed it out.
He wrote three alternative theories and crossed out two.
He wrote: Function: debated. Possibly fitness signal — demonstrating speed and strength to predators, indicating this individual is not worth pursuing. Possibly confusion tactic — the herd's unpredictable vertical movement creating a visual problem for anything trying to select a single target. Possibly both. Possibly neither. The author notes that the impala has been doing this for several million years and the question has not been settled to anyone's satisfaction, which he finds, at this stage in the volume, rather companionable.