J 56 BRITISH BIRDS. [vol. xni. 



duet. It varies considerably in length and quality. Some- 

 times it is fairly short, and consists only of a single phrase. 

 At other times it is pitched higher, and oscillates up and down 

 in a series of very short phrases. In this case it almost 

 always lasts a much longer time. 



I have no doubt that careful observation will distinguish a 

 number of lesser variations given under slightly different 

 emotions. 



The duet in its most typical form is given by the two birds 

 of a pair close together, more or less facing each other, with 

 their necks stretched straight up. It is thus accompanied 

 by an attitude somewhat different from the ordinary, a little 

 stiff and ceremonial in character. It may issue from among 

 the reeds, or from a pair on the open water. As far as my 

 observations go, it is not preceded by any special action. 

 The birds may be resting, fishing, or swimming steadily. 

 Frequently the birds will come up after a number of fishing 

 dives, give a duet, and at once start fishing again. If not 

 very close together at the start, the}^ almost always swim 

 towards each other during the performance. Neither does 

 the ceremony lead to other sexual actions. Like the head- 

 shaking of the Great Crested Grebe, it is self-exhausting, 

 and after it is over the birds resume their previous activities. 



I have so far seen no other mutual ceremonies in this 

 species, but it is quite possible from analogy with P. cristatus 

 that there is one common and several rarely performed 

 ceremonies, which latter I have not yet had the luck to witness. 



When the call is begun by a single bird from among the 

 reeds (i.e., when the birds of a pair are very likely not within 

 view of each other) there is often not a true duet, but after 

 the lapse of a few seconds another bird, which we cannot be 

 positive is the mate of the first, takes up the call, and prolongs 

 it for some time after the other has stopped. 



Miscellaneous Notes. 



Swimming Habits. — The pond where I was watching is a 

 good-sized sheet of water, over half a mile across, with small 

 reed-beds along one shore only. In spite of this the Dab- 

 chicks were to be seen on every part of the water, almost 

 invariably in pairs. They have a curious habit of making 

 interminable journeys across the pond, for no apparent reason, 

 the two birds swimming close together at a sharp pace. 

 During these journeys the neck is held rather straight, not 

 bent forward, as in the Great Crested Grebe. Now and again 

 the head is dipped quickly till it touches the water as if to 



