446 BULLETIN 179, UNITED STATES NATIONAL MUSEUM 



about on their short, weak legs and roll pellets of mud, which they 

 place on top of the upper mandible and so bear to the nesting site." 

 Lucien M. Turner (1886) confirms this: 



"I have watched them for hours at a time, and when my eyes were not to 

 exceed four feet from the birds at worli. * * • The neck is stretched out 

 nearly its full length and the head kept with the bill at a right angle to the 

 neck. A slight pressing of the beak into the earth and a tugging twist of 

 the body gently pulls toward the bird a small pellet of mud. The bird then 

 lowers its neck to the ground with the beak on the opposite side of the pellet 

 (or on the side next the bird.) The beak is now thrust under the pellet until 

 the mass of mud is pushed onto the top of the bill and rests against the forehead. 

 This is the manner in which it obtains the mud and is in position to enable 

 the bird to deposit it. The mud is also smeared with the top of the beak. 



Professor Herrick (1935), on the other hand, says : 



The mud, which, as we have seen, is always carried in the barn swallow's 

 ample mouth and throat, is pressed out through the partially opened mandibles 

 as a semiliquid mass, at first in small and later in larger globules, a little here 

 and a little there. These globules are eventually laid down in tiers or rows, 

 and their uniformity is due to a uniform method of production and disposition. 



This semifluid building mud or clay is made to adhere to a previously moistened 

 surface of the wood by a peculiar tapping movement of the bill. * * * To 

 secure this all-important contact a small area is first thoroughly moistened by 

 repeatedly bringing the bill to it simultaneously with a visible muscular con- 

 traction in the throat region which presses out of the mouth drops of a liquid 

 which, from the freedom with which it runs along the grain of the wood, must 

 be mainly, if not wholly, water. 



The masonry is started with a mud disk, or plaque, attached to 

 the vertical surface, around and on which the structure is built up; 

 the layers of mud are alternated or mixed with pieces of grass or 

 straw ; these are short at first and worked in with the mud, but later, 

 longer pieces are used and the ends left hanging to some extent. "The 

 method of depositing and fixing these little spears was interesting. 

 A bird would come with a delicate blade or stem held crosswise in 

 its bill, and the moment it touched the beam, a small pellet of wet 

 mud would issue from the mouth and, like a drop of sealing-wax, fix 

 it promptly to the vertical surface." 



Both sexes work together, industriously and harmoniously, in the 

 construction of the nest. Professor Herrick's birds took eight full 

 days of upwards of 14 hours each to complete their nest ; they "began 

 their working-day as early as five in the morning, and they did not 

 wholly rest from their labors until eight o'clock at night." They 

 brought a load of material about every two or three minutes. 



Dr. Harold B. Wood, who has sent me some notes on this subject, 

 evidently agrees substantially with Professor Herrick on all the 

 above points. A nest that he watched near Harrisburg, Pa., was built 

 in six days. Dr. Dickey tells me that, from his observations, a pair of 

 bam swallows will average 12 days in building a nest and will some- 



