° 1916 J Huxley, Bird-watching and Biological Science. 259 



And what relation does it ha\'e to migration in migratory species? 

 (In the Killdeer it appears to take place before migration (see be- 

 low), while in the migratory species of Old-world Warblers 

 (Sylviidse) it begins, as is well-known, after migration. See Eliot 

 Howard ('07) for details on this point.) 



(4) What is the mechanism, so to speak, of pairing-up? Is force 

 used by the cock to the hen? (I do not think any cases of this are 

 known.) Are there fights between cocks or between hens for the 

 privilege of staying in the proximity of the bird of the opposite sex, 

 who meanwhile is comparatively passive (the males of Mocking- 

 birds and Thrushes seem to do this, and possibly the females too; 

 Eliot Howard records many cases of such fighting among hens in the 

 Sylviidse). Does the cock chase the desired hens until one consents 

 to receive his advances? (This seems to be a very general method. 

 It holds in many Ducks, probably in the Grebe, and in such species 

 as the Killdeer, to speak only from my own experience.) Are there 

 any special displays or other ceremonies associated with pairing-up, 

 or does courtship in the sense of definite ceremonies only begin 

 later? (It appears that the latter is frequently true. On this point 

 compare what happens in Man ; before some agreement is reached, 

 courtship is merely a series of approaches; it is only later that a 

 purely objective observer, from Mars or elsewhere, would be able 

 to record the existence of definite "ceremonies." On the other 

 hand, the period of "approach" is characterized by a certain 

 amount of " display -action " — attention to dress, showing-off of 

 prowess, etc. — and in birds too there must exist something of the 

 sort. The best-known example is the song of the migratory 

 Sylviidse in Europe, where the males, who have migrated some days 

 before the females, attract their mates by singing. It will be of 

 great interest to see whether other birds show the same sort of 

 display, only appealing to the eye instead of the ear.) 



(c) Courtship & Display: (1) Song: What are its dates of 

 starting and stopping, and its relation to other activities? (In the 

 Nightingale the song of the male ceases immediately the young 

 are hatched, while the Song Thrush (Turdus musicus) sings nine 

 or ten months of the year). Do both sexes sing? and if so, are the 

 songs alike? (In the Cardinal the hens certainly sing, but not so 

 well as the cocks.) 



