186 WESTS 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 witli white tips. 



The nest of tlie 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 

 Trochilidfe, 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 

 "procreant cradle" is rocked by the temi^estuous \vinds of the tropics. A somewhat similar 

 structure may be seen in the nests of many other percliing 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. No ordinary wind could 

 have shaken the eggs out of tlie 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 buUt 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 npon the ground. In proportion to the growth of 

 the young, the mother increased the height of her walls, so that by the time the young were 

 ready to iiy, the nest had been transformed from a shallow, saucer-like structure, into a round 

 and deeply-hollowed cup. It has been suggested in explanation of this curious beha\dor 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. 



In 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 liitherto 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 efl'ects of rain or atmospheric influences, as long as the 

 mother bird is seated upon them. Mr. R. 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. 



Tlie injurious effect of a sudden increase of electricity is very strongly marked upon the 

 young of all animals, the hurtful influence lieing 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-stonn. In climates where thunder- 

 storms are so frequent and violent as in the lands which are inhabited by these birds, it is 

 needful that the eggs should be protected from the deadly influence, and we accoi'dingly 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 iu the 

 temperate climates of Europe. In the AVest Indian Islands, with the exception of the pigeon 

 tril)es 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 o]>ening 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 Miisicapa olivacea (a fly-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 



