THE BIRDS OF NORTHERN THAILAND 215 



This great bird is well known to the northern people and is the sub- 

 ject of many superstitions, some of which I recounted in 1931. The 

 belief that the killing of one of a pair will cause the death of the other 

 is quite true during the breeding season, when the female is walled up 

 in the nesting hole and wholly dependent upon the male for food. 



From some mountain summit one may often hear the loud barking 

 calls of this species, especially toward evening, and looking down 

 the slopes see a pair or small flock traveling above the forest-canopy 

 with alternate sailing and flapping of wings. Each downward beat is 

 accompanied by a chuffing sound (like that of a steam locomotive get- 

 ting under way) , which carries for an immense distance. 



At about 5,000 feet on Doi Aug Ka in April I discovered a pair 

 breeding in a gigantic tree ; the cavity was perhaps 75 feet above the 

 ground. A juvenile was taken at Doi Mon Khwam Long, July 18. 

 An adult male of September 16 is molting remiges and rectrices. 



Just at the base and on top of the central pair of tail feathers is a 

 large, exposed gland, densely covered with short, gray-brown pilose 

 feathers. From this gland exudes a bright yellow oil, with which, 

 in living adults, the bill, foreneck, and central wing bar (but not the 

 other white portions of the plumage) are liberally stained. I have 

 myself seen a bird rub its bill against the gland and then smear the 

 oil along the outspread wing. In death the brilliant color soon fades 

 to buff or wholly disappears. 



An adult male had the irides red; the orbital skin black; the casque 

 deep yellow, orange on top, black behind and on the sides near the 

 front ; the basal three-fourths of the culmen black ; the maxilla yellow, 

 red at the tip, black at the extreme base ; the mandible white, black 

 at the base ; the interior of the mouth black, orange near the tip ; the 

 feet and toes olive-slate ; the soles brown ; the claws slate. 



A juvenile male with the casque represented merely by a soft swell- 

 ing had the irides brown; the lower eyelid livid flesh; the upper 

 eyelid and the orbital skin dark slate; the bare skin of the throat 

 livid purple ; the culmen red-orange, lighter at the tip ; an ill-defined 

 sagittate mark from the nares with its point on the culmen slaty 

 brown, blacker in the narial region, this mark edged orange-red below ; 

 between the culmen and the nares a whitish area; the maxilla other- 

 wise with the apical half bright yellow, then whitish, and the basal 

 fifth blackish, the edges of the commissure blackish on the basal two- 

 thirds ; the mandible with the tip light orange, otherwise light gray- 

 green, more plumbeous toward the base, a streak running lengthwise 

 below bright orange, the edges of the commissure orange, paler toward 

 the base and with the basal fifth black ; the interior of the mouth gray- 

 green, with an orange median ridge on both floor and roof; the bare 



