138 NILS GYLDENSTOLPE, ZOOLOGICAL RE8ULTS OF THE SWEDISH ZOOLOGICAL EXrEDITIONS TO SIÅM. 



Davison states that this species was »extremely conimon in every stream through- 

 out the province» (Tenasserim) and Robinson & Kloss found it »abimdant every where 

 011 the coast and on the tidal estuaries, whereever there was mangroves» dnring their 

 Expedition to the Northern parts of the Malay Peninsula. 



In Siarn it must, however, be very rare and during my whole Expedition I only 

 observed three specimens at the Meh Tha river in Northern Siarn. One male in full plu- 

 tnage was shot here on the 4th of May 1914. 



It is neither included in Williamson's list of the birds of Bangkok, nor does Barton 

 mention it from Raheng and neighbourhood. 



292. Ardeola grayi. Sykes. — The Pond Heron. 



Ardeola grayi: Williamson 1 p. 48; Gairdner p. 31; Grant p. 116: Gairdner p. 152. 



ef Koh Lak 2ä /i 1915. L = 535 mm.; W = 227 mm.; T = 94 mm.: C = 68 mm.; Tarsus — 61 mm. 

 - § Koh Lak Via 1914. L = 470 mm.; W = 198 mm.; T = 77 mm.; C = 57 mm.; Tarsus = 55 mm. - 

 lrides: yellow. Bill: brownish black with the base nf the lower mandible yellowish green. Legs: greenish yellow. 



The Pond Heron was very common in a mangrove swamp near Koh Lak in the 

 Siamese Malaya. When I travelled down by rail from Bangkok to Koh Lak several 

 specimens of a Pond Heron were observed on suitable localities along the railway line. 

 These specimens probably all belonged to this species. 



In the North of Siarn it is replaced by the Chinese Pond Heron to which it is very 

 similar when in vinter plumage. However, Ardeola grayi »Sykes may be distinguished 

 by its smaller size. 



The Pond Herons are most of ten seen on the paddy-fields where their plaincolouring 

 lielp them to escape notice, but when they take to flight their white wings make 

 them a conspicuous object. Their note is verv harsh and croaking. 



293. Ardeola bacchus. Bp. The Chinese Pond Heron. 



Ardeola bacchus: Gyldenstolpe I p. 73; Gyldenstolpe Q; Gyldenstolpe 111 p. 236; Robinson & Kloss p. 15; 

 Robiuson II p. 143; Robinson III p. 726. 



J 1 Pak Koh */* 1914 - L = 498 mm -; w = 2 ' 6i mm -; T = 95 mm -; c = ,i4 mm - — ef fa k Koh 20 ,:' 

 1914. L = 495 mm.; W = 204 mm.; T = 83 mm.; C = 61 mm. — $ Fak Koh % 1914. L = 460 mm.; 

 W = 204 mm.; T — 77 mm.; C = 61 mm. - [rides: yellow. Bill: horn colour (ba«o of lower mandible 

 yellowish green). Legs: yellowish green. 



The Chinese Pond Heron replaced the last-nientioned species in the Northern parts 

 of the country, and it seems to live more along small creeks than on the paddy-fields or 

 swamps. 



A fine male speoimen in full breeding i">lumage was shot at Pak Koh on the 4th 

 of April 1914. The other specimens obtained are in their winter plumage and then very 

 similar to A . grayi Sykes, but even in that plumage the Chinese Pond Heron may be dis- 

 tinguished by its slightly larger size. 



