THE BIRDS OF NORTHERN THAILAND 207 



stream. When a passing insect is sighted, a bird will leave its perch 

 and, after a few wing beats and a snap of the bill, glide in a wide circle 

 back to the same resting place, all the while uttering a musical, trill- 

 ing note. 



De Scbauensee has remarked (1929) that he found this species nu- 

 merous at Chiang Mai in December but practically absent in March 

 and April. With the advance of the dry season it restricts itself 

 more and more to the river shores and other wet areas, but the true 

 reason for its apparent rarity in April and May is the fact that vir- 

 tually the whole of the local population is then gregariously breeding 

 in holes in the high banks of the Mae Ping some miles above Chiang 

 Mai. In June and July, when the fields are again filled with water, 

 bee-eaters occur everywhere. Late in October and early in November 

 the species is sometimes extraordinarily abundant on the marshes, 

 owing to the temporary presence of enormous flocks of what are prob- 

 ably true migrants from farther north; I have no record of a cor- 

 responding return movement during the dry months of spring. 



Perhaps because of underground nesting, the plumage, especially 

 the elongated central rectrices and the feathers of crown and nape, be- 

 comes excessively worn and bleached ; the green portions tend to be- 

 come verditer blue, the rufous pale brownish. Examples taken in 

 July and August are in molt. 



I find no mention in literature of the not infrequent occurrence of 

 yellow-throated birds in the summer months. This variation seems 

 to be rather common among juveniles but is seen also in certain very 

 worn adults. 



Mature birds of either sex had the irides crimson ; the bill black ; the 

 feet and toes purplish brown, slaty brown, or brownish black; the 

 claws black. A juvenile had the irides brown ; the bill black ; the feet 

 flesh color ; the toes gray ; the soles whitish ; the claws slaty black. 



The adult in fresh plumage has the upperparts bright green, in cer- 

 tain lights glossed with copper, this latter color very strong on crown 

 and nape; the concealed portions of the remiges rufous (very conspic- 

 uous in flight) ; a black line through the eye, edged below by a streak 

 of verditer blue ; a narrow black gorget between the throat and breast ; 

 the underparts otherwise copper-glossed green, bluer on the throat, 

 paler on the belly and under tail coverts, the light rufous bases of the 

 feathers showing through in places, especially on the flanks. The 

 immature is similar but is duller everywhere and lacks the elongated 

 central rectrices. 



