SAiJD DUNES AND SALT MARSHES 



cormorants when pursued take to the shore. 

 This would suggest a terrestrial ancestry of 

 these birds, and, according to Gadow, cormo- 

 rants strikingly resemble the new-world vul- 

 tures, and the habit of both these birds of sit- 

 ting with their wings spread is suggestive. 

 The fact that cormorants on rising into the air 

 hop with the feet together, although their 

 usual gait is a waddle, suggests a former ar- 

 boreal life, and many cormorants still nest in 

 trees. 



The tree dwellers naturally hop from 

 branch to branch, and it is probable that the 

 earliest birds were arboreal. When the tree- 

 dwelling bird descends to the ground it nat- 

 urally 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 walk- 

 ing gait, therefore, may be understood to indi- 

 cate a long custom of feeding or dwelling on 

 the ground. Although the flicker is fre- 

 quently seen on the ground, the ground habit 

 is probably but recently acquired, for it has 

 not learned to walk, while the robin, for ex- 

 ample, is able to run and does so much more 

 often than he hops. Young robins show, how- 



290 



