.8,.. OBSERVATIONS AND CORRESPONDENCE. 479 



the dead trees a convenient perch. The single rather deep pond 

 which this enclosure contained has been rightly done away with, and 

 three smaller and shallower ones substituted; in which old pond I 

 have more than once been interested by observing the Night Herons 

 swimming — usually for only a few strokes, it is true, when they got 

 out of their depth in bathing or reaching after floating food. But on 

 one occasion one bird, driven into the water from an island by another, 

 swam quite easily and composedly to the shore. Although the Common 

 Heron is well known to be capable — as apparently are most birds of 

 wading habits — of natatorial feats, I am not aware that similar 

 performances have been before observed in the case of Nydicovax 

 griseus, which sits as lightly on the water as a gull. 



These occurrences are interesting, as showing how a shore bird 

 might gradually and naturally, through seeking food on steep banks, 

 become a swimmer ; and others, noticed in these gardens and 

 elsewhere, tend to show that the surface-feeding Anatine ducks could 

 easily develop a diving habit. In the Northern Pond, last year, 

 I was fortunate enough to see a male Mandarin Duck {Aix galericulata) 

 dive repeatedly and energetically for food, and Mr. C. Bartlett 

 informed me that the Summer Duck (A. sponsa) will likewise do so. 

 The young of the Chilian Pintail [Dafila spinicauda), yet in down, 

 repeated the performance elsewhere in the gardens at another time. 

 This accomplishment may prove to be more common among the 

 Anatince than is generally supposed ; on four occasions I have detected 

 it in the half-domesticated Mallards in the London parks, the birds 

 being in one case ducklings in down. Swainson states that the Gadwall 

 [Anas stvepeva) dives as easily and frequently as the sea-ducks ; but I 

 have not yet witnessed the action on the part of this species, though 

 examples are at present in the Society's collection. The distinct 

 little group of Tree-Ducks appear also to have the plunging habit, 

 which I have noticed in the case of three species [Dendrocygna major, 

 D. vagaus, and D. viduata) before the deep pond in the Night Herons' 

 quarters, where they are placed, had been altered. Of course, the 

 surface-feeding ducks dive when in play, but the action in that case 

 is very different, and easily distinguishable from the purposeful plunge 

 of a feeding bird. 



That the Tree-Ducks should dive is not to be wondered at, as 

 their general build and the large size of their feet, in spite of their 

 long eggs, distinctly recall the Fuliguline subfamily. 



While on the subject of the ducks, it may be mentioned that the 

 Common Foxes in the Zoological Gardens readily ate a specimen of the 

 Common Sheldrake. As this bird is reputed to nest unharmed in an 

 occupied fox-earth, and to be more than indifferent human food, it 

 seemed possible that its very conspicuous appearance, in both sexes, 

 and even in the first plumage, might possibly be of warning signifi- 

 cance. It would be, however, very desirable to repeat the trial with 

 a perfect specimen, as the bird given to the foxes had been plucked 

 and disembowelled, circumstances having prevented me from carrying 

 out my original intention of making myself the corpus vile of the 

 experiment. I have no doubt, however, that I should have been able 

 to discuss Sheldrake with toleration, as I could not discover any 

 undue unpleasantness, or even fishiness, in the flavour of the Red- 

 breasted Merganser or the Great Crested Grebe, to say nothing of 

 the Scaup and Golden-eye, which appear not to be considered very 

 good eating. 



Two Red-billed Hornbills {Toccus erythrovhynchis) being at present 



