244 
Birds of Celebes: Bucerotidae. 
in Cranorrhinus cassidiv. On the whole the whngs suggest that Rhytidoceros is 
more given to flying than the other genera. The following actual observations on 
the flight of the Bucerotidae tend to prove this. Prof. Newton in his “Dictionary 
of Birds” (1893, 435) states that Tickell in his manuscrijjt “Birds of India” 
(in the library of the Zoological Society of London) “divides the Hornbills of 
that country into two genera only, Buceros and Aceros, remarking that the birds 
of the former fly by alternately flapping their wings and sailing, while those 
of the latter fly by regular flajrping only”. Anthracoceros coronatus may be taken 
as typical of the former class, as is shown by Legge’s corresponding observa- 
tion: “when flying it proceeds with rather quick-flapping of the wings, and then 
sails along with them outstretched, its long tail and motionless primaries giving 
it a singular asj^ect ... It usually does not take long flights; when it does the 
momentum of its huge bill and heavy neck are such as to cause it on alight- 
ing to topple forward before gaining its equilibrium” (B. Ceylon, 1880, 274). 
Davison observed the same mode of flight in JDichoceros hicornis (Str. F. VI, 99), 
so, also, Bourdillon in the same species (Str. F. lY, 387), in Anthracoceros 
convexus, here called Hydrocissa albirostris (t. c. p. 101), and in Ptilolaemus tickelli 
(p. 104). Berenicornis flaps regularly, but “keeps in small parties about the 
lower trees and undergrowdh” (p. 106). 
As to Rhinoplax vigil, Hartert (J. f. O. 1889, 367, 368) remarks that it is 
“a bad flier, even worse than Buceros rhinoceros” . On Cranorrhinus corrugatus in 
E. Sumatra Dr. Hagen (T. Ned. Aardrijk. Genootschap 1890, (2) VII, 139) has 
published the following observations: it has “like all Hornbills a heavy clumsy 
flight, accompanied by a peculiar ringing whizzing noise. After about each 
kilometer of the way (they flew daily from the sea-side to their roosting-trees 
inland) they rested for some minutes on suitable tall tree-tops. The resting- 
places are fixed points, and, if they are not scared, the birds may be expected 
with tolerable certainty every evening at the appointed time”. It is thus seen 
that at least seven of the eleven genera of the Bucerotidae of the Indian countries 
and Great Sun da Islands have poor pow'ers of flight: Anthracoceros, Buceros, 
Dichoceros, Ptilolaemus, Be^-enicornis, Rhinoplax, Cranorrhinus. 
The flight of the wide-spread Rhytidoceros appears to be in marked contrast 
to these. 
Davison writes of Rhytidoceros suhrujicollis and undulatus: these sjrecies “are 
remarkably strong on the wing, and morning and evening, where they occur, 
numbers may be seen flying far overhead, sometimes at such a height that they 
look not bigger than Crows. The strokes of their wings are accompanied by 
a peculiar metallic or resonant swish') which can be heard at an incredible 
distance. One is often made aware of these birds flying far overhead by the 
Bernstein (J. f. 0. 1861, 111) tries to explain the noisy flight liy the movement of the air in the 
large air sacks, an exiflanation which appears to us very far-fetched; neither does Mr. 0. Grant’s 
explanation (0. B. XVH, 347 note) appear satisfactory. In our opinion the sound need not be explained in 
any other way than the noise caused by the flapping of the wing of many other large birds. 
