most nests ; still, the old habit is so powerful that nests ai'e seldom built without it, though the quan- 

 tity is often very limited. The cavity is thickly lined with fine fibres, slender grasses, dead moss, and 

 horse-hairs, the circular arrangement of which, es2:)ecially about the rim, forms a striking contrast to the 

 jumbled appearance of the foundation and superstructure; occasionally, feathers, wool, and plant-down 

 are used in the lining. The mud, besides giving form and solidity to the structure, is the stucco which 

 holds it to its support. Some nests built upon horizontal surfaces in protected spots, have very little 

 mud in their composition, and this is principally about the base. The diameter of the cavity at the 

 rim averages about two and one-half inches ; its depth, about one and one-half inches. The external 

 dimensions of a nest built against a perpendicular wall are as follows : Distance across the widest part 

 of the flattened side, five and one-quarter inches; distance from the rim to the lowest point, five and 

 one-quarter inches. The diameter of the base of a nest taken from a shelving-rock is five and one-half 

 inches; depth, four and one-half inches; width at top, three and three-fourths inches. 



EGGS: 



The complement of eggs is usually five. The shell is white, with a very faint creamy-tint; some- 

 times it is -marked about the crown with a few reddish-brown specks or spots. I have several times 

 found nests containing one or two such eggs, the remainder being normal. They averngo in size .74 x 

 .57 of an inch; from this they rarely vary more than .05 of an inch. 



DIFFERENTIAL POII^TS ; 



The eggs can usually be identified by careful measurements and attention to the curve of the out- 

 line, together with the tint of the shell. The eggs of the White-bellied Swallow, Rough-winged Swallow, 

 and the white eggs of the Indigobird resemble them somewhat. The nest cannot easily be mistaken for 

 the work of any other bird. 



REMARKS : 



The nest represented by Plate X was built early in May, against an inch plank, used as a brace 

 between the timbers of a wooden culvert, about four feet above the surface of the run. It contained 

 five fresh eggs. The road passing over the bridge was much traveled, but the clatter of horses' hoofs 

 and rattle of wagons, though loud and frightful to a person beneath, did not seem to annoy the birds, 

 which, judging from the various marks of former nests, had occupied the place for a number of years. 



Attachment to the nesting locality is more or less manifested by all our birds, but in none is it 

 stronger than in the Pewce. Throughout their lives, if circumstances are favorable, the same pair will 

 return every spring to their first nesting-spot, and sometimes even bring with them their ofi'spring, to 

 build in the immediate neighborhood of their birth-place. This habit endears them to the country 

 people— in fact, to all who are acquainted Avith the bird— and "the nest on the porch pillar" is as 

 studiously guarded as if an unfailing omen of good luck. 



Semi-domestication is beginning to tell upon the nest of this species, as it has already done upon 

 some others. Now and then, a structure is found in which no mud at all is used. I have seen one, 

 taken from a beam of a shed, in which no earth was employed, for, not exposed to wind or rain, it was 

 sufficiently strong without it. It is not impossible that, in time, the mud may be entirely discarded, and, 

 instead of the clay-house, with its beautiful moss-covered walls, will be seen simply a nest of grasses 

 and fibres in some well-protected place about the dwelling of man. 



60 



