264 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1936 



On this occasion a troop of eight had been at least 36 hours in the 

 particular valley visited, and but for the mildly disturbing effect 

 of our party might have remained there another couple of days. Un- 

 disturbed, there was no apparent intention of their leaving the local- 

 ity, and during a period of several hours the troop was feeding in 

 an extremely tiny area. But in this instance there had been a strik- 

 ing deviation from what is imagined to be the normal sleeping pro- 

 cedure, for, with the exception of the occupant of the lofty bed 

 previously mentioned, all the animals had slept on the ground 



The sleeping quarters were at the base of a large tree surrounded 

 by a dense tangle of undergrowth. For about two-thirds of the way 

 round the tree base a broad, shallow trench a few inches in depth had 

 been scooped out of the dry soil, which constituted a wonderfully 

 cozy bed and refuge, effectively screened and protected by the almost 

 solid canopy of interwoven stems and matted foliage. At each end 

 of the trench and along its outer perimeter was banked up the 

 scooped earth and a pile of rubbish such as dead leaves and twigs. 

 It was impossible to conjiicture in what attitude these gorillas had 

 slept, but the containing bank may have served both for protection 

 and comfort. This communal bed was as filthy as usual, and from 

 the freshness of the excreta had not been used for more than one 

 night. One of the droppings was so immense that my gun-bearer 

 naively remarked that it looked more like an elephant's. This 

 dormitory was in the center of the small area in which the troop was 

 feeding. The treetop bed some 50 yards higher up the hillside most 

 certainly overlooked the ground shelter, though of its occupants 

 presumably nothing could have been seen. 



This terrestrial sleeping-place conclusively upset any theories pre- 

 viously held as to the whys and wherefores of the tree-building habit, 

 to account for which no satisfactory explanation can at present be 

 advanced. A spell of dry weather may have induced ground sleep- 

 ing, or an expectant mother unable to climb satisfactorily may have 

 required protection; but if so, was it the old male up the tree, and 

 why? If a birth was imminent his women-folk may have made him 

 keep his own company, though he would still act as their guardian 

 by day. It is all very intriguing. Tree-climbing for food is readily 

 understandable, but tree-climbing to go to bed is another matter, 

 and requires explanation. 



Beds in trees are suggestive of protection, not comfort, but there 

 is no apparent reason why such security is necessary. It cannot 

 be for fear of leopards for there are as many, and possibly a great 

 deal more, on Mufumbrio. Locally, no tales were heard of excep- 

 tional abundance, and the leopard theory is untenable. In the past 

 there may have been frequent incursions of lions from the Lake 



