66 BULLETIN 208, UNITED STATES NATIONAL MUSEUM 



known) and yet get enough wax regularly (practically all specimens 

 collected have had wax in their gizzards) shows that guiding is not 

 necessary. That it probably never was essential seems to be reflected 

 in the fact that it did not "carry over" into the other phylogenetic 

 branches of the family. 



Evolution of the habit 



Reference to our discussion of the phylogeny of the species of 

 Indicatoridae will show that the guiding habit is restricted, as far 

 as we know, to one branch of the family, that comprising part of the 

 subgenus Indicator, including /. variegaius and I. indicator. We still 

 have no data as to guiding in a third related species. /. archipelagicus, 

 which, on phylogenetic grounds, might conceivably be expected to 

 reveal some signs of such behavior. There is, unfortunately, a similar 

 lack of knowledge of the habits of the species supposedly nearest to 

 the progenitor of the whole line, /. maculatus, but in that species there 

 appears to be less reason to expect guiding, unless in a very incipient 

 form, than there is m /. archipelagicus. Enough is known of the 

 habits of I. minor to be able to say that it does not guide humans, and 

 the same seems to be the case for its smaller relative, /. exilis, while 

 our Icnowledge of the species of Prodotiscus makes it clear that they 

 do not possess any guiding tendencies and do not even feed on bee 

 comb. In a specialized derivative from the typical Indicator stock, 

 Melichneutes robustus, guiding is still to be demonstrated. The aerial 

 evolutions of this bird can hardly be connected with guiding behavior, 

 as they "lead" to nothing but empty sky, and when the bird does 

 finally descend into a tree it is after a course that no nonvolant creature 

 could possibly have followed. These aerial gyrations would seem 

 more probably to be a matter of courtship activity, but their real 

 nature remains to be discovered. 



Although guiding behavior is known for only two species of Indicator, 

 we do know that all the honey-guides except Prodotiscus eat beeswax. 

 From the admittedly meager accounts of their habits and from the 

 trapping of several species in the West African forests, we know that 

 other species (/. maculatus, I. exilis, and M. robustus) come to places 

 occupied by wild bees to peck at any wax they can reach. This is also 

 true of I. archipelagicus and /. xanthonotus in Asia. As may be seen 

 in our discussion of their feeding habits, /. indicator, I. variegatus, 

 and /. minor can and do get wax from accessible wild bees' nests at 

 times by themselves, but it is true that many and possibly most of 

 these sources are not readily available to them until opened by some 

 other bee predator. In this way the birds come in contact with other 

 creatures attracted by honeycomb, some of which are better equipped 

 and more able to open these hives and make accessible their contents. 



