180 LIFE H1STOEIES OF NORTH AMERICAN BIRDS. 



does not begin nest building before the second week of May, and unfavorable 

 weather may delay it until the 1st of June. Only a small quantity of glue is 

 secreted daily, and therefore the completion of the entire structure requires 

 about eighteen days. After two-fifths of the nest is completed (the work of one 

 week) the laying of eggs begins. The process of construction may be retarded 

 by cool weather (lack of food) and by continued rains (softening of glue). The 

 bird can control the laying of eggs ; can discontinue for one or more days, if she 

 thinks necessary. Incubation begins before the last egg is laid and lasts eighteen 

 days. The setting parent shields the structure by habitually covering its base 

 Avith the breast and pressing the head against the walk above. After the young 

 are eight days old they arrange themselves in the same manner. When the 

 sitting bird is disturbed, it at first seeks to frighten the intruder by fluttering 

 and then hides below the nest. The young, when a fortnight old, also hide under 

 the nest, where they can not be seen from above. "When three weeks old, they 

 flutter and try to frighten the intruder with a hissing noise, and always remain 

 2 to 3 feet below the mouth of the chimney (shaft), where they are fed by the 

 parents. The young do not leave the chimney before they are four weeks old. 

 Under the most favorable conditions a late brood can not be brought to a suc- 

 cessful end in less than fifty-eight (five eggs) to sixty (six eggs) days, while an 

 early brood (begun the middle of May) may consume from sixty-five to seventy 

 days." 



In a subsequent letter, dated August 20, 1894, Mr. Widmann writes me as 

 follows : 



"Another season confirmed my former statements in regard to the breeding 

 habits of the Swifts. The pair began building and laying at the regular time; 

 but after the second egg was laid, on May 23, some misfortune happened, and 

 next day the eggs were found on the floor below, and no more were laid until 

 June 10, when laying began anew. Within eight days (June 10 to 17, inclusive) 

 five eggs were laid. On the 14th, after the third egg had been laid, the bird 

 began to .set. On the 24th one egg had rolled out, leaving four in the nest. 

 July 1, on the eighteenth day of incubation, the eggs began to hatch, but the last 

 of the four young did not leave the shell until July 3. This bird remained much 

 behind in development, while one of the three others always kept a little in 

 advance. The latter left the shaft for the first time July 26, but the youngest did 

 not get ready to go out until August 7, a difference of eleven days. 



"The event of a young Swift leaving the chimney for the first time is made 

 known all over the neighborhood by great excitement and noise. While the 

 species for some weeks before have been quiet and inconspicuous, great activity 

 and noise is suddenly noticed, and numbers are seen chasing through the air. This 

 indicates the event, and it occurred for the first time again on July 17 being the first 

 young raised in the neighborhood. It was particularly noticed that the young 

 Swift is entirely naked when it leaves the shell, and not only the eyes but also the 

 ears are, or appear to be, closed for the first few days. The eyes open by degrees. 

 The best developed specimen of the four had the eyes open for occasional brief 



