186 
NESTS OF HUMMING-BIRDS. 
of the tail is yellowish-green, and all the feathers of the tail, with the exception of the two 
central feathers, are furnished with white tips. 
r l he nest of the Vervain Humming-bird is very small, in accordance with the dimensions 
of the architect, is round and cup-like in shape, and beautifully constructed of cotton fibres 
and other soft and warm substances. As is the case with the nests of almost all the species of 
Trochilidse, the rim is so made as to curve slightly inwards, and is, in all probability, con- 
structed for the purpose of preventing the eggs from rolling out of the nest when the 
piocreant cradle is rocked by the tempestuous winds of the tropics. A somewhat similar 
stiuctuie may be seen in the nests of many other perching birds, and I well remember seeing 
the nest of a goldfinch which had been built at the extremity of a long and slender horizontal 
spray of oak, and which was completely turned inwards at the rim. Ho ordinary wind could 
have shaken the eggs out of the nest, as even when the branch was seized and drawn towards 
the ground, the eggs still remained in their places. 
In one species, which was watched by Captain Lyon, the nest was not completed until 
the young birds were nearly fledged. 
The mother bird built a small and rather shallow nest, in which she laid two eggs, and 
began to sit as usual. As soon, however, as the young were hatched, she set to work again 
at her nest, and added fresh material round the edges, so as to raise the sides and prevent her 
offspring from tumbling out of their house upon the ground. In proportion to the growth of 
the young, the mother increased the height of her w r alls, so that by the time the young were 
ready to fly, the nest had been transformed from a shallow, saucer-like structure, into a round 
and deeply -hollo wed cup. It has been suggested in explanation of this curious behavior on 
the part of the mother bird, that her completed nest had been destroyed, and that she was 
forced to run up a hasty kind of hut for the reception of her young, and could only finish it 
when she was relieved from the constant duty of sitting on her eggs. 
Lsr the nesting of the Humming-birds, there is one peculiarity that is worthy of a passing 
notice. In almost every case where a nest has hitherto been discovered, the materials of which 
it is composed are thick, soft and woolen, and in all instances are arranged in such a manner as 
to shield the eggs even from the effects of rain or atmospheric influences, as long as the 
mother bird is seated upon them. Mr. 11. Hill, who has paid close attention to the nests of 
the Humming-birds, . has ingeniously hit upon a connection between their structure and the 
electrical conditions of the atmosphere. 
The injurious effect of a sudden increase of electricity is very strongly marked upon the 
young of all animals, the hurtful influence being in proportion to the growth of the victim. 
Eggs are peculiarly susceptible to* the influence of electricity, and even when the chick is 
partially matured, are often killed by a passing thunder-storm. In climates where thunder- 
storms are so frequent and violent as in the lands which are inhabited by these birds, it is 
needf ul that the eggs should be protected from the deadly influence, and we accordingly find 
that the nests are oval or rounded in shape, and are made of substances which are bad con- 
ductors of electricity. In accordance with this principle, Mr. Hill proceeds to remark that 
“ in tropical climates, there are a greater number of birds that build close nests than in the 
temperate climates of Europe. In the West Indian Islands, with the exception of the pigeon 
tribes and the Humming-birds (which latter build deep, thick, cottony nests), the nests are 
almost uniformly circular coverings of dried grass, varied by intermingled cotton, moss and 
feathers, with an opening from below, or an entrance at the side. 
“ The Banana bird weaves a hammock of fibres, sometimes of horse-hair, deep and purse- 
like, and loosely netted; the • Musicapa olwacea (a fiy-catcher), a hanging cot of withered 
leaves, straw, moss, fibrous thread, and spiders’ webs fitted together ; and the mocking-bird 
builds in the midst of a mass of wicker-work a neat nest of straw lined with hair. The wood- 
pecker and the parrots take to hollow trees, but I hardly know any arboreal besides which 
constructs any nest that is not wholly covered or domed over. 
“Very many insects that are exposed to the air during their metamorphoses weave cover- 
ings of silk and cotton, in which they lie shrouded, at once impenetrable to moisture, and 
