THE BIRDS OF NORTHERN THAILAND 35 



a greenish-yellow patch under each nostril; the mandible yellowish 

 green, with the upper half black at the base; the feet and toes greenish 

 yellow ; the soles yellow ; the claws horn. 



This is a small, squat heron, which sits with its head drawn in 

 so that it seems to have no neck. It has the crown and a long crest 

 black ; the neck and underparts gray ; the upperparts chiefly a bronzed 

 green, which may look bluish in the field. Immature specimens ap- 

 pear largely brownish gray. The wing length of the present sub- 

 species ranges from 165 to 180 mm. 



ARDEOLA BACCHUS (Bonaparte) 



Chinese Pond Heron 



B[uphus] bacchus Bonapabte, Conspectus generum avium, vol. 2, 1855, p. 127 



(Malay Peninsula). 

 Ardeola grayii, Gyldenstolpe, Ibis, 1920, p. 769 ("Throughout the whole 



country"). — de Schauensee, Proc. Acad. Nat. Sci. Philadelphia, 192S, p. 578 



(Chiang Mai) ; 1929, p. 5S7 (Mae Rim). — Deignan, Journ. Siam Soc. Nat. 



Hist. Suppl., 1931, p. 173 (Chiang Mai) ; 1936, p. 73 (Chiang Mai). 

 Ardeola bacchus, Gyldenstolpe, Kungl. Svenska Vet.-Akad. Handl., 1913, p. 73 



(Den Chai) ; Journ. Nat. Hist. Soc. Siam, 1915, p. 236 (listed) ; Kungl. 



Svenska Vet.-Akad. Handl., 1916, p. 138 (Pha Kho) ; Ibis, 1920, p. 769 



("Northern Siam"). — Deignan, Journ. Siam Soc. Nat. Hist. Suppl., 1931, p. 



173 (Chiang Mai) ; 1936, p. 73 (Chiang Mai). 



This is one of the commonest and most familiar of northern birds, 

 occurring anywhere in the lowlands at some time of the year: on 

 the ricefields or the marshes, along streams both large and small, 

 in roadside ditches, at wet places in the deciduous forests, and even 

 for some distance up the mountain slopes along the wider torrents. 

 In addition to the localities listed above, there are definite records 

 for Khun Tan (six specimens without data in Stockholm, taken by 

 Eisenhof er) ; for Wiang Pa Pao, where I saw it in April, 1929 ; for 

 Phayao, where I observed it, August 28, 1929; and for Ban Pak Li, 

 a village on the Nan river, where I took a specimen, April 7, 1937. 



The seasonal movements of this bird require further study. At 

 Chiang Mai, where alone continuous observations have been made 

 over a period of years, the species is rare or absent from March to 

 August, the very time when water is most plentiful and other herons 

 are most numerous. Since these are the months when it wears full 

 nuptial plumage, it is clear that it goes elsewhere, perhaps farther 

 north, to breed. All my specimens had the gonads inactive, with 

 the sole exception of a female, taken April 9, which had the ovaries 

 slightly enlarged. 



Examples collected by me had the irides deep golden-yellow; the 

 eyelids edged bright yellow ; the orbital skin and lores yellow-green, 

 sometimes with a blackish mark in front of the eye; the culmen and 



