254 4A THEORY OF BIRDS’ NESTS. 
that this is only an apparent 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 
harmonize 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 other surrounding objects, before we can say 
that the bird, when sitting on its nest, is really con- 
spicuous. It has been remarked that small patches 
of white and black blend at a short distance to form 
grey, one of the commonest tints of natural objects. 
5. Sunbirds (Nectarineide). In these beautiful 
little birds the males only are adorned with brilliant 
colours, the females being quite plain, yet they build 
covered nests in all the cases in which the nidification 
is known. This is a negative rather than a positive 
exception to the rule, since there may be other causes 
besides the need for protection, which prevent the 
female acquiring the gay colours of her mate, and 
there is one curious circumstance which tends to 
elucidate it. The male of Leptocoma zeylanica is said 
