THE BIRDS OF NORTHERN THAILAND 41 



the upperparts light vinaceous-brown ; the tail black; the under- 

 parts pale buff ; the wing coverts buff and the apical half of the wing 

 black. The immature is streaked above and below with rufous and 

 buff, but, like the adult, is recognizable by the distinctive wing pattern. 



IXOBRYCHUS EURHYTHMUS (Swinhoe) 



Von Schrenck's Bittern 



Ardetta curhythma Swinhoe, Ibis, 1873, p. 74, pi. 2 (Amoy and Shanghai, China). 

 Ixobrychus eurhythmus, Deignan, Journ. Siam. Soc. Nat. Hist. Suppl., 1936, p. 

 169 (Ban Mai Tong Hong). 



Von Schrenck's bittern is a species that breeds in Japan and north- 

 ern China and winters in the Malay Peninsula and the Malaysian 

 islands ; its main migration route is coastal. The only specimen known 

 from the interior of Thailand is a female taken by me, May 2, 1936, 

 near Ban Mai Tong Hong, a village near Muang Thoeng. Whether 

 this unexpected occurrence signifies that the species regularly migrates 

 in small numbers up the valley of the Mae Khong, or whether my 

 bird was merely a straggler, cannot yet be decided. 



The specimen was collected beside what seemed to be an abandoned 

 gem pit in the midst of an extensive mixed-deciduous forest — a highly 

 improbable place for a member of this genus. 



The male is entirely dark chestnut above and buff below. The wing 

 pattern is like that of sinensis, but the apical half of the wing is dark 

 gray rather than black and the inner primaries and outer secondaries 

 are narrowly tipped with white. The female has the upperparts dark 

 chestnut, conspicuously spotted with white on back and wings, and the 

 underparts buff, streaked with blackish. 



IXOBRYCHUS CINNAMOMEUS (Gmelin) 



Cinnamon Bittern 



[Ardea] cinnamomea Gmfxin, Systerna naturae, vol. 1, pt. 2, 1789, pp. 643-644 



(China). 

 Ardetta cinnamomea, Gyldenstolpe, Journ. Nat. Hist. Soc. Siam, 1915, p. 236 



(Khun Tan) ; Kungl. Svenska Vet.-Akad. Handl., 1916, p. 139 (Chiang Rai). 

 Ixobrychus cinnamomeus, Deignan, Journ. Siam Soc. Nat. Hist. Suppl., 1931, 



p. 173 (Chiang Mai) ; 1936, p. 74 (Chiang Mai). 



At Chiang Mai this heron appears about the middle of January 

 and thereafter is common (even abundant during the rains) until 

 about October 23. Gyldenstolpe found it very common about Chiang 

 Rai in August 1914, and I saw many at Phayao between August 24 

 and 28, 1929. An undated specimen in Stockholm was collected by 

 Eisenhofer at Khun Tan. I have taken it at Ban Pang Ai, July 23, 

 1935; at Ban Huai Som, March 29, 1937; at Doi Ta Kong, June 1, 



