228 



The Philippine Journal of Science 



1918 



their brighter coloration above and below, but the difference is 

 hardly worthy of recognition by name. 



An interesting question is raised by the occurrence on Mount 

 Banahao of several avian species that are found there but not on 

 other mountains near to it. The present species furnishes one 

 example, Leucotreron marchei another. These birds were taken 

 at low elevations on Mount Banahao, from 600 to 900 meters 

 (2,000 to 3,000 feet), heights which are found on Mount Maqui- 

 ling, for instance, where these birds do not occur. The explana- 

 tion may be that some of the higher mountain forms, such as 

 the present, are accustomed to descend to lower levels but do 

 not inhabit isolated peaks like Mount Maquiling, where the 

 greater altitudes are not available for retirement when desirable.. 

 Undoubtedly a vertical migration of sorts takes place on the 

 mountains in the Philippines, which brings numbers of birds 

 to lower altitudes during the rainy seasons and sends them up- 

 ward when the lower slopes of the hills feel the effect of the 

 dry weather. To lend strength to this theory, it may be stated 

 that the rains were prevalent about Mount Banahao when these 

 observations were made in December. 



I have seen also on Mount Banahao, at over 1,800 meters' 

 elevation (6,000 feet), a black thrush, Planesticus sp. ?, and a 

 Phyllergates near philippinus, neither of which was secured. 

 Owing to the height at which they were seen, they hardly enter 

 the above discussion. My specimens of Z. ivhiteheadi are as 

 follows : 



Table V. — Specimens of Zosterornis whiteheadi. 



No. 



Sex. 



\ 



Locality. 



Date. 



994 

 1000 

 1001 

 1321 

 1325 

 1332 

 1330 



d 



.d 



9 

 d 

 d 

 d 

 9 





May 10, 1914. 

 May 11, 1914. 



Do. 

 December 30, 1915. 



Do. 

 December 31, 1915. 



Do. 



do 



.do . _. 





do - — 



do - 



do - - - 





Zosterornis aflBinis McGregor. 



This interesting species has been known heretofore from ^ 

 single male collected in 1904 on Mount Mariveles, Bataan Prov- 

 ince, Luzon, by A. Celestino. I have since collected a number 

 of specimens on Mount Maquiling, Laguna Province, including 

 the first known female of the species. 



The female may be described as indistinguishable from the 



