64 BULLETIN 208, UNITED STATES NATIONAL MUSEUM 



display or not (and I think it is doubtful), the actions involved in it 

 lead us to ask, as von Uexkiill (1909) did, how drives and motives are 

 related. What we seem to have here is something akin to a non- 

 purposive pattern extending over into one that superficially gives the 

 appearance of having an anticipated purpose or usefulness. 



Antiquity of the habit 



A habit that depends for its expression on the cooperation of two 

 totally independent animals cannot have developed suddenly, or 

 recently, as some writers have suggested. These writers were prob- 

 ably misled by thinking that guiding was primarily a matter of lead- 

 ing humans, and that, therefore, the habit could not be older than 

 the presence of humans. As we now know, this is not the case, and, 

 as we shall see, guiding is probably an old, and, in an evolutionary 

 sense, a residual habit, and like many relicts is neither essential to the 

 species that have it nor productive of any descendant differentiation. 



We may recall, at the risk of repetition, that of all the honey- 

 guides only one group, and that a relatively "primitive" one (at least 

 the one least differentiated from the hypothecated ancestral stock), 

 developed the guiding habit, although all but Prodotiscus feed on 

 bee comb, and all of these would have opportunities to meet with 

 foraging mammalian or other associates at bees' nests. We know 

 definitely, from direct observations, that an apparently nonguiding 

 species. Indicator minor, sometimes comes to a bees' nest as it is 

 being opened by natives who were led to it by a greater honey-guide, 

 and that it feeds on the bits of comb together with the bird that did 

 the guiding. As already intimated, it cannot be said that the lesser 

 honey-guides, or some others of these species, do not have any guiding 

 tendencies merely because they do not make any attempt to lead 

 humans, but in the case of so well known a species as /. minor we 

 would probably have had some observational evidence by now if it 

 did associate itself with any other creature in its raids on bee comb. 

 In the literature one often finds the statement that the honey-guides 

 are poorly equipped to open bees' nests unaided, and this is supposed 

 to help account for their having assumed a symbiotic relationship 

 with animals more able to tear open these food sources. Yet, of all 

 the honey-guides, the ones that have entered into such mutual forays 

 on the bees are among the very species -with the largest, most power- 

 ful bills. The evolutionary trends in the honey-guides have produced 

 two lines characterized by reduction in bill size, one leading to the 

 subgenera Melignothes and Pseudofringilla and the other to Meligno- 

 mon and Prodotiscus. One line has retained the large bill, the sub- 

 genus Indicator and its specialized ofl'shoot, Melichneutes. The sub- 

 genus Melignothes, as illustrated by /. minor, its best known species, 



