^'''^•iQ^l^^^j TowNSEND, Bird Genealogy. 289 



never before left the nest. I repeated the experiment several 

 times with the same result. A fact of considerable interest in this 

 connection is that "A Pigeon with a perfectly webbed foot [was] 

 evolved at Cambridge by only three years' selected crossings." ^ 

 This may be looked upon as a case of reversion. The throwing 

 of somersaults in the air similar to those of the Tumbler Pigeon 

 has been reported in the case of the Black-bellied Plover. 



The Sheathbill, Chionis, is so ancestral and generalized in its 

 type that it suggests all the groups we have just been considering. 

 Anatomically it is allied to the Oyster-catchers and the Gulls. It 

 is often classed among the Plovers, but it is as marine in its haunts 

 as are the Auks, and in flight it resembles the Gulls. Its appearance 

 on land, gait and manner of courting are very much like those of 

 a Pigeon, and it goes by the name of ' Kelp Pigeon.' 



While young Terns take to the water, young Cormorants when 

 pursued take to the shore. This would suggest a terrestrial an- 

 cestry of these birds, and according to Gadow, Cormorants strik- 

 ingly resemble the New World Vultures, and the habit of both 

 these birds of sitting with their wings spread is suggestive of 

 kinship. The fact that Cormorants on rising into the air hop with 

 the feet together, although their usual gait is a waddle, suggests 

 a former arboreal life, and many Cormorants still nest in trees. 



Tree dwellers naturally hop from branch to branch, and it is 

 probable that the earliest birds were arboreal. Wlien the tree- 

 dwelling bird descends to the ground it naturally hops there also, 

 but hopping is not a satisfactory method of progression for a 

 ground-feeder, — it does not permit of cautious approach, and it is 

 decidedly jarring. A walking gait, therefore, may be understood 

 to indicate a long custom of feeding or dwelling on the ground. 

 Although the Flicker is frequently seen on the ground, the ground 

 habit is probably but recently acquired, for it has not learned to 

 walk, while the Robin for example is able to run, and does so much 

 more often than it hops. Young Robins show, however, their 

 arboreal ancestry by hopping more than they run. Pipits, Horned 

 Larks and Ipswich Sparrows have so completely departed from 

 arboreal habits, that they run easily and walk with grace. Walking 



1 T. Digby Pigoit, "London Birds and other Sketches". London. 1902, p. 239, 



