Death-Feigning Instinct in the Ostrich. 211 



known where an adult ostrich has been come upon quite suddenly, 

 as from the top of a kopje, and the bird was apparently so startled 

 by the apparition that it at once collapsed on the ground with its 

 neck and head outstretched, and made no attempt to escape. The 

 primary instinct of death-feigning was here the first to assert itself, 

 not that of escape. 



Mr. Guy A. K. Marshall has observed the habits of the wild 

 ostrich in Mashonaland, and states that in one case the bird squatted 

 after running for some considerable distance and dodging about among 

 some low bushes. In a second instance, coming suddenly over a rise in 

 quite open country, three ostriches were seen about 400 yards away. 

 They detected the intruder at once and dropped like stones, being 

 then almost indistinguishable from the ant heaps among which they 

 were feeding. Upon continuing to walk towards them., they evidently 

 recovered from their collapse, rose up, and soon made off out of 

 sight. 



Such well-authenticated observations prove conclusively that 

 the ostrich may retain its instinct of death-feigning into the adult 

 state ; it is not resorted to so freely as when the bird is young, 

 but it still comes into action under certain conditions. The circum- 

 stances calling it forth seem to be sudden or intense alarm or fear. 

 Under ordinary conditions of alarm the birds take to flight, but when 

 suddenly alarmed, without perhaps a chance to escape, they follow 

 an instinct which is more usual in the young. It is easy to 

 understand the advantage gained by this gradual change of response. 

 While very young the chicks would scarcely be able to escape an 

 etLcmy by running, and hence death-feigning is an advantage to them, 

 and is the usual procedure on alarm ; as they become stronger and 

 fleeter their increased bulk would result in exposure and danger, and 

 thus they resort almost entirely to flight. 



It is manifest that the ostrich has, as it were, a choice of actions 

 when alarmed : either it can drop down and rely upon its inertness 

 and close resemblance to its surroundings for protection, or it may 

 take to running and depend upon its fleetness for escape. It is more 

 likely to follow the former while young, the latter as it grows older. 

 It may even act differently under what seem to be similar circum- 

 stances. As in many animals, particularly those higher in the scale, 

 there is an element of uncertainty as to which of several possible 

 courses may be chosen in an emergency. 



An instinct which seems very closelv related to the above is 

 sometimes displayed by brooding or nesting birds. In this parental 

 duty the cock and hen occupy the nest alternately, the hen mostlv 

 by day and the cock by night ; to be somewhat accurate, the hen sits 

 from 8 or 9 a.m. to about 4 p.m., and the cock from 4 p.m. to 8 or 

 9 a.m. The greyish colour of the female bird usuallv harmonises 

 very closely with the natural surroundings bv dav and the blackness 

 of the male bv night. There can be little question that these sexual 

 differences are the results of natural selection. Under ordinary cir- 

 cumstances the wild or semi-wild ostrich will sit with its long neck 

 erect as if on the look out, but immediately it espies any danger, as 



