MEROPS BULLOCKOIDES. 
DIMENSIONS. 
Inches. Lines. 
Length from the tip of the bill to the 
point of the tail 7 6 
of the tail 4 0 
of the bill from the angle of 
the mouth 1 7 
Inches. Lines. 
Length of the wings when closed 4 6 
of the tarsus 0 3^ 
of the middle toe 0 3 
of the hinder toe 0 2 
The female resembles the male, with the exception that the colours are not 
quite so bright. 
Between this species and Merops Bullockii many discrepancies might be 
instanced, but the diagnostic character, which will prove the most readily 
available, is the colour of the upper tail coverts. In the present species, this 
colour is invariably similar to that of the lower ones, whereas in Merops 
Bullockii it is very different. 
It was not until the expedition attained the 25° of south latitude that this bird was disco- 
vered, though north of that it appeared not uncommon. When observed, it was generally 
either perched upon the tops of trees, along the immediate banks of rivers, or in the act of 
making short circuits through the air, apparently in chase of flying insects. As may be infer- 
red from the structure of its wings, it is not a bird which flies for any great length of time 
without resting ; it seeks its food during frequent low and short flights, and after each of these, 
often returns to the perch from whence it proceeded. In respect of its habits, as well as its 
wings, it closely resembles Merops Erythropterus, Lin. ; but, in regard to both these ehaiacters, 
it differs from the other species of the genus yet observed in South Africa. Upon the modified 
structure of the wings in this species and M. Erythropterus may depend the circumstance of their 
being permanent inhabitants of the districts where they arc found, and where they encounter 
a cold during the winter much more severe than ever occurs farther to the southward, and from 
which the Merops Apiaster, Lin. M. Savignii, Levaill. and M. chrysolaimus, Jard., fly towards 
the end of summer. From observations I have had occasion to make, I think it probable that 
the migrations, both of birds and quadrupeds, will be found often to depend more upon causes 
which have hitherto been comparatively overlooked, than upon any absolute deficiency of food 
in the countries from whence they retire. Connected with this opinion, I may instance the cir- 
cumstance of a species of swallow, which inhabits the mountains of the Cape Colony during 
the summer months, repairing in the winter to the vicinity of houses left, by another species, 
on the approach of the cold season. It there finds food sufficient for its support, till the other 
species, gifted with more vigorous powers of flight, and a superior courage, returns and drives 
it back again to situations which it had for a time abandoned. 
