174 The Field Naturalist's Quarterly Aug. 



Thread-feathers, or " filo-plumes," are very much like 

 hairs, and are long and narrow, the vane being quite 

 rudimentary. Some of these thread - feathers are bristly, 

 or setaceous, and many birds possess a row of bristles, 

 vibrissse, along the opening of the mouth or gape. These 

 are conspicuous and very long in the Goatsuckers, and 

 the Flycatchers have them in a lesser degree. 



Feathers are liable to become damaged in the wear and 

 tear of constant use, and to meet this contingency they are 

 able to be easily cast and replaced by fresh feathers. This 

 process, moulting, takes place just after the breeding season 

 as a rule, and it is present among all birds from the ostrich 

 to the humming-bird. 



If the feathers of the wing and tail, which are used in 

 flight and which must become damaged, were not renewed 

 the bird would be unable to fly ; but, on the other hand, 

 if they were all shed simultaneously the event would be the 

 same, so that the flight-feathers are usually shed in pairs, 

 and in this way the bird is still able to seek its food or 

 escape its enemies. The large order of Ducks, Geese, and 

 Swans are, however, an exception to this rule, for most of 

 them shed all their quill-feathers at the same time, and are 

 thus for a short period unable to fly. But in the case of 

 ducks, their mode of living is such that they have other 

 resources for concealment and escape. Their food can be 

 obtained in or near water, and the aquatic plants and herb- 

 age serve them as an easy and effective shelter. 



Swallows moult in the spring, which is uncommon. A 

 number of birds have two moults in the year, and there are 

 even some species which have three. Thus the Ptarmigan 

 {Lagopus nmtus) moults three times in the course of a single 

 year. The first moult takes place immediately after the 

 breeding season, as is usual, both male and female becom- 

 ing grey in colour ; they then moult again and become white 

 for the winter, and in spring moult for the third time, adopt- 

 ing the plumage of the breeding season again. 



The second moult in some birds is often very partial and 

 limited to certain parts of the plumage, and it is still a moot 

 point as to how far some of the changes are due to actual 

 moulting or how far to the alteration of colour in the 



