July, 1906 



AMERICAN HOMES AND GARDENS 



37 



The growth of the bills of birds continues through life as 

 with our finger nails. Where freak or accident prevents the 

 proper meeting of the mandibles the resulting interference 

 with the ordinary functions of the bill minimizes the wear 

 to a point where it is exceeded by the growth, resulting, some- 

 times, in peculiar malformations. Such a case was exhibited 

 by a Porto Rican woodpecker which I collected. It had 

 suffered an injury to the lower mandible near the base. Ap- 

 parently, as this injury healed, the edges of the wound con- 

 tracted, warping the mandible to that side, and tending to 

 a corkscrew shaped growth. The bird was debarred from 

 hammering by the weak, misshapen bill, and thegrowthwhich 

 normally would have replaced wear abnormally prolonged 

 both mandibles, though why the lower so much more than the 

 upper is not easy to understand. In this bird the upper 

 mandible had exceeded the average length by about a third 

 of an inch, while the lower mandible was nearly three times 

 the normal length. The lower mandible made a half turn, 

 so that what should have been its lower surface, was, at the 

 tip, the upper. It would have been interesting to know if 

 this bird was able to feed on seeds and fruit, which normally 

 form a large part of the food of this species, or whether 

 it was fed by the mate, which was with it when shot. At 

 the time it was collected the stomach was empty, while 



Flickt 



Humming Bird 



Kingbird 



Red-Eyed Vireo 

 Bay-Breasted Warbler 



Song Sparrow 

 Black-Headed Grosbeak 



that of the mate contained the remains of a large 

 dragonfly. 



As in the time of Noah, the dove returned to the 

 ark with an olive branch in its Bill as a token of 

 promise, so now, each spring, the birds return to our 

 dooryards and shade trees, bearing nesting material, 

 as though it were a sign of the delightful intercourse 

 we may have, and the study of the beautiful creatures 

 we may enjoy if we will but meet them in friendly 

 spirit half way. 



The horny sheath of the bill is called rhampotheca 

 and is formed by the outer layers of the malpygian 

 cells. It resembles in structure the other horny parts, 

 such as claws, nails, and spurs. In some birds, as 

 some of the ducks, this covering remains soft except 

 near the tip, which contains tactile organs. In the 

 hawks and parrots the distal end of the upper man- 

 dible is hard; basal portion, called the cere, is thick 

 and soft. This latter is usually very sensitive, and in 

 it the nostrils are enclosed. 



In most species the cere is bare, but in some species 

 of parrots it is covered with feathers and in such cases 

 its structure is similar to the ordinary skin. 



The covering about the nostrils is soft in some spe- 

 cies and presents a means of externally closing them 

 though without special muscles. Such an arrange- 

 ment is called an operculum, and is prominent in 

 pigeons. 



In petrels and shearwaters the operculum forms a 

 complete tube, whence these birds are called Tubi- 

 nares or tube nosed birds. 



