116 CHANGE OF HABITS OF SOME MAINE BIRDS. 
a cup attached by one side to the building, with no covering 
whatever. One can easily see the causes which have 
gradually led the birds to adopt this form. Where they 
built against cliffs, there was a necessity for covered nests, 
and the rocks were so damp that the material of the nest 
kept moist, so that, although from the nests extending so far 
outward, there was atendency to separate from the base, the 
tenacity of the mud prevented it. Building in the same way 
on the sides of barns, the nests would not adhere to the 
boards when the weather was dry, and in consequence many 
nests fell and multitudes of eggs and young were destroyed. 
Besides, as the eaves of many barns projected so as to 
protect them, there was less necessity for covered nests. Thus 
gradually the style has changed, till now few nests are seen 
near settlements which bear any resemblance to Audubon’s 
plate. Two years ago, Isawa notable exception to this. At 
the “ Giant ” farm, near Caribou Lake, we saw these swallows 
in large numbers building in the old style. This farm is in 
the woods, ten miles from the next house, and some thirty 
miles from the nearest settlement. Whether these birds had 
never been near settlements, and so had not learned the latest 
improvements, or from whatever cause, they continued to 
build in the old way. 
I might extend this paper by mentioning changes in 
habits of other species, but sufficient has been said to show 
that birds, like people, are progressive, and those who ob- 
serve them closely will yet learn many things of which we 
are not now aware. 
