What animal was circling the camp?

On one night during his journeys from 1945 to 1950 in and around the Empty Quarter in Oman and Saudi Arabia, Wilfred Thesiger reports the following [1]:
When it grew dark we couched the camels,... I had just decided to get into my sleeping-bag when bin Ghabaisha [one of his Bedu companions] signed to us to be quiet and pointed to the camels. They had stopped chewing, and all of them were staring in the one direction. Our rifles were already in our hands, during these days we never put them down, and we slid quietly to the ground, crawling to the edge of the small basin in which we had camped. It was to dark to see anything, but the camels still watched something, although now they were looking farther to our right. I lay there motionless, straining to see what they saw. Shadows formed and re-formed but I could be sure of nothing. Bin Kabina [another Bedu companion] lay beside me. I touched him inquiringly but he made a sign that he too could see nothing. The cold rain which had soaked through my shirt ran down my flanks, and pattered on my bare legs. The camels started to chew the cud again and were no longer watching. I thought uneasily, ‘They are working round behind us.’ Amair and bin Ghabaisha evidently thought the same, for they moved farther round to watch the night behind us. Hours later I crawled to my saddle-bags to fetch a blanket, which I shared with bin Kabina. The rest of the night passed very slowly, and nothing happened.

What is your guess?
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Obviously Wilfred Thesiger and his Bedu companions didn't worry about an animal, but were thinking of raiders. The Empty Quarter is not that empty. One has to be alert, since uninvited visitors or raiding parties may approach through a valley or come over the sand dunes at any time. But this night it was an animal that was circling the camp. What kind of animal was it?
[1] Wilfred Thesiger: Arabian Sands (1959). Reprinted in Penguin Travel Library, 1991;
page 235.

Last update was made on March 29 in 2008 by Axel Drefahl
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