THE HONEY-GUIDES 79 



Bacterium coli from a number of species of birds, and considers the 

 organism an obligatory intestinal bacterium in birds that feed pri- 

 marily on plant materials. In his convenient summary Stresemann 

 (1929, pp. 490^91) writes that Scheunert and Schieblich found B. 

 coll absent in the rock dove but a milk-souring bacterium {Strep- 

 tococcus acidi lactici) was present. Stresemann further states that the 

 cellulose of plants is not acted upon by ordinary enzymes but is 

 partly digested by the intestinal bacterial flora, which may be largely 

 confined to the caeca. That these bacteria are essential for the nor- 

 mal growth of young birds is indicated by experiments performed by 

 Schottelius. (Current studies (October 1954) reveal a wax-splitting 

 Micrococcus sp. and a possibly cerolytic yeast of the genus Cajidida 

 in the alimentary tract of the lesser honey-guide.) 



The study of the enzymes present in the honey-guide is also currently 

 under way but no definite results may be reported as yet. It is 

 hoped to further this approach as opportunities permit. 



Wax-eating in other birds 



While no other birds are known to eat wax, as such, as persistently 

 and in such amounts as the various species of Indicator (Prodotiscus, 

 on the other hand, is not a beeswax eater, although it gets a waxy 

 substance from the scale insects on which it feeds), there are some 

 other kinds of birds that do consume appreciable quantities of wax- 

 like materials. Many birds that feed on berries inadvertently swallow 

 the waxy coating of these fruits, but it is not known if they actually 

 digest the waxes present. In his account of the food of the North 

 American black-capped chickadee (Parus atricapillus) , McAtee (1926, 

 p. 86) writes that 30 percent of the food is vegetable matter and that 

 this is largely composed of the mast of coniferous trees and the wax- 

 covered berries of bayberry and poison ivy. Tree swallows (Iridop- 

 rocne hicolor) and myrtle warblers (Dendroica coronata) also eat large 

 quantities of bayberries, especially during the winter months. (Pre- 

 liminary studies (October 1954) indicate that the wax of bayberries 

 passes imchanged thi-ough the digestive tract of myi'tle warblers. 

 Further studies are being planned.) 



The honey-guides as a family (Indicatoridae) are most closely 

 related to the barbels (Capitonidae) . Barbels are not known to eat 

 wax as a regular, or even infrequent, part of their diet, and I cite the 

 following more as a suggestion than as a bit of evidence. C. J. Skead 

 (in litt.) tells me that he was informed by an old native and his son 

 that the black-collared barbel, Lybius torquatus, eats beeswax and 

 larvae when it can get them. They seemed very convinced of the 

 accuracy of their report, which was an unprompted one volunteered 



