VI 
A THEOllY OF BIBBS’ NESTS 
133 
Real or apparent Exceptions to the Law stated at page 124 
The only marked exceptions I have been able to discover 
are the following — 
1. King crows (Dicrourus). These birds are of a glossy 
black colour, with long forked tails. The sexes present no 
difference, and they build open nests. This apparent excep- 
tion may probably be accounted for by the fact that these 
birds do not need the protection of a less conspicuous colour. 
They are very pugnacious, and often attack and drive away 
crows, hawks, and kites ; and as they are semi-gregarious in 
their habits, the females are not likely to be attacked while 
incubating. 
2. Orioles (Oriolidse). The true orioles are very gay birds ; 
the sexes are, in many Eastern species, either nearly or quite 
alike, and the nests are open. This is one of the most serious 
exceptions, but it is one that to some extent proves the rule ; 
for in this case it has been noticed that the parent birds 
display excessive care and solicitude in concealing the nest 
among thick foliage, and in protecting their offspring by in- 
cessant and anxious watching. This indicates that the want 
of protection consequent on the bright colour of the female 
makes itself felt, and is obviated by an increased development 
of the mental faculties. 
3. Ground thrushes (Pittidse). These elegant and brilliantly - 
eoloured birds are generally alike in both sexes, and build an 
open nest. It is curious, however, that this is only an ap- 
parent exception, for almost all the bright colours are on the 
under surface, the back being usually olive-green or brown, 
and the head black, with brown or whitish stripes, all which 
colours would harmonise with the foliage, sticks, and roots 
which surround the nest, built on or near the ground, and 
thus serve as a protection to the female bird. 
4. Grallina Australis. This Australian bird is of strongly 
contrasted black and white colours. The sexes are exactly 
alike, and it builds an open clay nest in an exposed situation 
on a tree. This appears to be a most striking exception, but 
I am by no means sure that it is so. We require to know 
what tree it usually builds on, the colour of the bark or of 
the lichens that grow upon it, the tints of the ground, or of 
