124 BULLETIN 195, UNITED STATES NATIONAL MUSEUM 



day was 82, although the average number per day during the incubation period 

 had been only 43 V2. This unusual restlessness, however, was exceptional, since 

 our records for other females are much steadier. 



The female during the next few days gradually resumed her normal rate 

 of activity. During the next 6 days when she spent considerable time brood- 

 ing the young, the periods of attentiveuess averaged about 13%o minutes and her 

 periods of Inattentiveness about 4%o- 



Wlien both adult birds were busy from morning till night with the feeding 

 of the young, periods of attentiveness and inattentiveness still were the rule. 

 The adults would feed the young several times in succession and then talie 

 a short period off when they would get some food and rest for themselves. 

 Sometimes they would feed the young repeatedly and rapidly nine, ten, or 

 more times before they would stop. Then again the number of feedings per 

 period would be only three or four, or in many cases, but one. Usually the 

 number of feedings per period averaged higher in the morning than in the 

 heat of the day. 



Baldwin (1921), through his exhaustive banding operations at 

 Cleveland, Ohio, has shown that house wrens are not permanently 

 mated. Not only do they change mates from season to season but also 

 they shift mates between the two nesting periods of the same season. 

 His banding records indicate also that the house wren breeds the 

 season after hatching when it is one year old. Out of 156 wrens banded 

 during the 5 years between 1915 and 1920, 10, or 6% percent, re- 

 turned either to the same or to other nesting boxes on his premises. 

 In more recent banding results Kendeigh (1941) reported a 75 per- 

 cent return ratio of adults. Baldwin observed the details of the 

 life history of seven different nests of which the following is typical : 

 The nest was started on July 4 and completed 2 days later, July 6. 

 The set of eggs was completed on July 13 and hatched on July 26, an 

 incubation period of 13 days. The young left on August 10 after 

 spending 15 days in the nest. The total cycle required 36 days. 



Col. S. T. Walker, of Milton, Fla., made the following detailed 

 observations of a pair of nesting house wrens (Kidgway, 1889) : 



I was sick at the time, and watched the whole proceeding from the 

 laying of the first stick to the conclusion. The nest was placed in one of 

 the pigeonholes of my desk, and the birds effected an entrance to the room 

 through sundry cracks in the log cabin. 



Nest begun April 15th. 



Nest completed and first egg laid April 27th. 



Last egg laid May 3d. 



Began incubation May 4th. 



Hatching completed May 18th. 



Young began to fly May 27th. 



Young left the nest June 1st. 



Total time occupied 47 days. 



The time spent by the young in the nest, as reported by various 

 observers, varies from 12 to 18 days. Burns (1921) states the com- 

 plete nesting cycle of the house wren is 35 to 45 days, whereas Be- 

 wick's wren and the chickadee require 52 to 53 days. 



