434 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1911. 



other insects. Too often is this the case when trying to follow the 

 flight of some small bird, the beating of the little wings being quite 

 too rapid for our senses. We will here confine ourselves to those 

 birds possessed of ample expanse of wing, for, generally speaking, 

 the larger the wing the less rapid is the beating, and therefore the 

 more easily can we follow its movements. 



To gain the velocity in order to create the resistance necessary for 

 the support of all heavier-than-air "machines," some birds run or 

 swim, others simply spring into the air and by the vigor of their 

 flapping achieve the same result; while others, again, launch them- 

 selves from some coign of vantage — a tree or rock — and in falling 

 gain the desired resistance. In this article I give some particulars 

 regarding the latter method, illustrated by photographs of the 

 Gannet (Sulci hassana). 



Stepping to the cliff edge, and, if there is no cause for undue haste, 

 having raised and partly unfolded its wings, the bird prepares to 

 dive into space. This dive, it should be noted, is not directed down- 

 ward, but rather as horizontally outward from the cliff as may be 

 (sometimes it appears to have even an upward tendency). If the 

 bird is one possessed of broad large wings not much altitude is lost, 

 and it skims through the air in much the same fashion as does a 

 piece of cardboard thrown horizontally. If, however, as in the case 

 of auks, the wings are small and narrow and the body heavy, then 

 the bird at first drops nearly vertically, only being able to gain a 

 more horizontal course as its velocity increases. 



Sometimes birds of this latter class, presumably through mis- 

 judgment of the space they have to work in, do not get the horizontal 

 course in time, and crash into the rocks or sea at the foot of the 

 cliff. This is very noticeable when a group of puffins (Fratercula 

 arctica) hurriedly takes flight from a steep bowlder-strewn slope. 

 Under these circumstances I have frequently seen quite a number 

 of birds come to grief on the rocks within 30 yards of starting. 

 Most of these, though somewhat dazed by the impact, flutter and 

 claw their way on to the top of some big bowlder, and after a 

 moment's pause again dive forth, but not infrequently with no 

 better result. The first failure is, I believe, often caused by their 

 paying too much attention to and looking behind at whatever startled 

 them, instead of gauging their proper angle. 



The raising and unfolding of the wings is worthy of a little con- 

 sideration. The former usually takes place not after, but previous 

 to, the diving or springing forward, while generally the whole "foot" 

 is at rest upon the rock. Of course, when suddenly alarmed birds 

 sometimes cast themselves from the cliff without first raising their 

 wings, and in consequence fall rapidly. 



