102 BULLETIN 2 08, UNITED STATES NATIONAL MUSEUM 



ten minutes and as it did not return climbed up and removed the piece of bark 

 and to my surprise there were two eggs. 



Unfortunately both eggs were broken when the collector fell from 

 the tree as the branch gave way under him. Some time later he found 

 another pair of the barbets also trying to keep a scaly-throated honey- 

 guide away from their nest. Three days later he opened the nest and 

 found it contained six eggs, four of which were black-collared barbet's 

 and two were honey-guide's eggs, attributed to I. variegatus, "white, 

 very glossy, oval in shape, measuring 21.72 mm. X 16.5 mm. and 

 20 mm. X 16.5 mm." 



The above observations yield the following data: The scaly-throated 

 honey-guide did not remove an egg of the host when laying its own, 

 and the total time spent by the laying bird in the nest of its victim 

 was very short — three seconds from the time it entered until it left. 

 Mr. Neub3^-Varty further informs me that this particular instance of 

 egg laying took place between 9 and 9:30 a. m. 



Eggs attributed to this honey-guide measure 20-21.7 by 15.4-17 

 mm., compared with 20.3-22.6 by 14.5-17.9 mm. for /. minor and 

 22.7-26 by 16.8-19.6 mm. for /. indicator. While those eggs included 

 in the measurements for /. variegatus are ones whose attribution to 

 that species seems well founded, it must be emphasized that the only 

 completely authentic one measures 20.7 by 16.5 mm. as compared with 

 a similarly indisputable oviduct egg of I. minor measuring 21.5 by 

 16.8 mm. As far as the admittedly meager material indicates, it 

 seems that the scaly-throated honey-guide lays a relatively small egg 

 for its size compared with either of the other two species here men- 

 tioned. In the case of the parasitic cuckoos of the genus Cuculus, 

 small egg size has been looked upon as an adaptation to the egg size of 

 their common victims or hosts, but it is not at all clear that this is the 

 case here. Actually, in most cases {Lybius torquatus, Trachyphonus 

 vaillanti, Mesopicus griseocephalus, Campethera 7iubica) the eggs of the 

 host are larger than those of, or attributed to, the honey-guide, a 

 condition of no apparent advantage to the parasite. It is possible, 

 but not probable, that the absence of starlings from the list of hosts, 

 if real and not due to paucity of data, may be correlated with the 

 small size of the eggs of this honey-guide, which might tend to make 

 starlings unsuitable to the parasite. 



The eggs are laid only in nests in holes in trees or in banks ; I know 

 of no record of a scaly-throated honey-guide egg or chick in any other 

 type of nest. As far as known, with one exception (and that one not a 

 definite record), the eggs are laid in nests of birds that also lay pure 

 white eggs. The apparent exception is Petronia superciliaris, the 

 yellow-throated sparrow. 



