THE HONEY-GUIDES 15 



honey-guides in relation to their total history as a family of birds 

 than it is in any of the other four avian families exhibiting this mode of 

 reproduction. In the Icteridae and the Anatidae parasitic breeding 

 is a relatively recent development, as it also seems to be in the Ploceidae 

 (where it has actually developed twice in unrelated parts of the family). 

 In the Cuculidae it gives evidence of greater antiquity (it is distributed 

 over a larger number of genera and species, and possesses, in some 

 cases, extreme specializations of host specificity, of host egg resem- 

 blance, and of eviction of nest mates by the nestling parasite). In 

 the Indicatoridae alone do we find that the majority (possibly all) of 

 the included species are parasitic. Also, in this family we find that 

 the birds have "lost" more of the "ordinary" features of the reproduc- 

 tive behavior cycle than in the other parasitic groups. To use the 

 terminology of Kendeigh (1952), the honey-guides show less "attentive 

 behavior" than do the other parasitic birds. The general scarcity 

 of courtship and the lack of any signs of mutual exclusiveness between 

 males (of I. indicator and /. minor, at least) at the stud posts (see p. 125) 

 are significant. The difference between the highly developed and 

 much-indulged-in courtship behavior in the parasitic cowbirds and 

 weavers, and even some cuckoos, and the lack or infrequency of such 

 behavior in the honey-guides is striking. On the other hand, it is true 

 that a type of rustling flight, reaching a remarkable degree of evolution 

 in the lyre-tailed species, has developed in these birds, but whether it 

 is really a form of mutual courtship activity is not yet clear. 



Together with this phylogenetic "loss" of parts of the behavior 

 cycle, there are a number of "gains" or developments that have 

 transpired in connection with the parasitic habit in the Indicatoridae. 

 The most striking of these is the development of a pair of bill hooks 

 in the newly hatched chicks of at least two and possibly other species 

 of the genus Indicator. Just how many species of honey-guides have 

 these hooks is not known, but it is now clearly understood that they 

 are used in the process of eliminating nest-mate competition by the 

 young bird. It is true that as yet we have direct observations on but 

 single instances of nest-mate attack or eviction by two species of 

 honey-guides (/, indicator and /, minor), and in one of these species 

 (7. indicator) the adult female often does away with the need for such 

 attack by puncturing the eggs when laying its own in the nest. In 

 this matter of getting rid of nest mates the parasitic habit in the 

 honey-guides agrees with that in some of the cuckoos, but not with 

 that in the weavers or in the black-headed duck (the only parasitic 

 duck). Cowbirds frequently eliminate nest mates by severe com- 

 petition with them for food by the young parasite, and not by direct 

 attack on them. 



