78 BIRD BEHAVIOUR 



and Snake-birds (Plotus), it is a mere pimple-like 

 rudiment, as it is also in the curious Shoe-billed 

 Stork {Balanicep rex) ; it is tempting in this case 

 to put its disappearance down to the necessity for 

 clearing the course for swallowing large prey, but 

 it is very doubtful if this explanation is correct, for 

 a very short tongue, if not an actually rudimentary 

 one, occurs in groups with different feeding-habits, 

 while both long and short tongues are found in 

 groups where the food is the same. 



Thus, the animal-feeding Kingfishers and the 

 mainly fruit-eating Hornbills both have very short 

 tongues ; the Herons have long tongues, the Storks 

 short ones — both animal-feeders. Among vegetable- 

 feeders, the Toucans, though so like the Hornbills 

 in their form and habits, especially with regard to 

 the bill and its use, have long tongues ; the Part- 

 ridges have tongues of suitable length for their 

 beaks, the Tinamous, so like them in feeding and 

 general habits, very short ones, like their giant 

 relatives of the flightless Ostrich tribe, all of which 

 are short-tongued, including the small worm-eating 

 Apteryx. 



It would seem, therefore, that in most cases the 

 possession of a tongue proportionate to the bill 

 or a very shoj;t one is a group-character, and that 

 the organ is in a state of degeneration in many cases. 

 I may mention, however, that in two cases I have 

 seen birds indulge in the curious — for them — action 

 of licking their chops ; in that of the Heron {Ardea 

 cinerea) and the Pied Kingfisher (Ceryle varia), both 



