ea. 
16,4 McGregor: Some Features of the Philippine Ornis 4831 
endemic species that reaches all groups except the Palawan 
group. The isolation of the Babuyanes and Batanes is evident 
when it is noted that Cacatua hematuropygia, Tanygnathus lu- 
cionensis, Pitta erythrogastra, P. atricapilla, and Rhipidura 
nigritorquis are found in none of those northern islands. Five 
common endemic species are found in all groups except Palawan 
and the Babuyanes-Batanes; these species are Zonophaps polio- 
cephala, Cyornis philippinensis, Pycnonotus goiavier, Copsychus 
mindanensis, and Cyrtostomus jugularis. 
Most of the endemic land birds are confined to single islands 
or groups of islands, and they can be used to indicate the relative 
distinctness of the various island groups. Counting the species 
that are confined to single groups of islands the following re- 
sults are obtained: 
Species 
Palawan group 40 
Central islands 32 
Mindoro 17 
Luzon group 61 
Samar-Leyte 27 
Mindanao 51 
Basilan 7 
Bongao-Sulu 30 
Romblon group 9 
Cebu 12 
Babuyanes-Batanes 14 
In general it may be stated that large islands of diversified 
topography, extensive highlands, and large areas of uncut low- 
land forest yield more species than do small low islands or islands 
from which most of the primary forest has been cut. In small 
islands, such as Cuyo, Cagayancillo, and Batan, there must be 
few if any unknown resident species, because it takes but a few 
days to visit all parts of any one of them. In Luzon, Mindoro, 
and Mindanao there are large areas of uncut forest, both lowland 
and highland, and no thorough zodlogical exploration has been 
carried on in any of these islands. Most of the work done so 
far has been the hurried gathering of specimens in limited areas 
for the purpose of discovering new species and adding data on 
distribution. None of this work has been either intensive or 
extensive. 
Aside from the possible discovery of unknown species, orni- 
thological work in any of the islands of the Archipelago will 
yield great quantities of information on the food, the nesting 
habits, the molts, and the migration of Philippine birds. 
