EASTERN HOUSE WREN 121 



break easily into pieces just suited for the purpose. The birds used 

 this wire to the practical exclusion of all other usual materials. 



The house wren has the habit of frequently building dummy or 

 extra nests, a trait common to other members of the wren family. 

 Many of these nests are built by the male prior to the arrival of the 

 female in the spring, but a mated male may use its superfluous energy 

 in building extra nests in the neighborhood of the one where his mate 

 is incubating the eggs. Even if a male is unsuccessful in obtaining a 

 mate, he may continue to build several nests during the course of the 

 season. The nests built by the male are crude structures, and it is 

 probable that some of the curious nests made of rusted wire nails and 

 other metallic material previously described are to be attributed to 

 the work of the male. In central IlKnois I observed both members 

 of a pair of wrens build three complete nests in different boxes before 

 selecting one for final occupancy. 



Mrs. Daisy Dill Norton (Forbush, 1929), of Lewiston, Maine, re- 

 ports a case in which an unmated female built a nest in a bluebird 

 house. It went througli all the manifestations of a maternal wren 

 with a family in prospect. She allowed no birds on her house or near 

 the nest and was ready to do battle with anything that appeared re- 

 gardless of size. The wren remained until the end of August, and in 

 all this time Mrs. Norton never saw another wren, nor did she hear the 

 song of the male. After the wren left, the box was taken down, and 

 inside was found an exquisitely built nest containing 12 (sterile) 

 eggs. From these observations it is apparent that the nesting instinct 

 is strongly developed in both the male and female house wren. 



One cannot watch a pair of wrens in their repeated attempts to 

 get long unwieldy sticks through a narrow box entrance scarcely 

 large enough to admit their tiny bodies without being greatly im- 

 pressed by their dogged persistence, energy, and skill. At first the 

 wren, especially if it is a young individual, may attempt to enter a 

 nesting hole with the beak grasped at the center of a long twig, but 

 very quickly through trial and error it learns to thrust one end of the 

 stick through the opening and then to inch it along with the beak until 

 well inside the nesting box. After the technique is mastered it is 

 not unusual for them to add four or five such sticks during the course 

 of a minute. In a single day they may accumulate a mass of sticks 

 several inches in depth, and in 2 or 3 days the entire structure is com- 

 pleted and ready to receive the eggs. 



Eggs. — The number of eggs in complete sets varies from 5 to 12, 

 but the range in numbers is usually 6 to 8 in the vast majority of nests. 

 Harlow (1918) in reporting on 47 nests of the house wren found in 

 New Jersey and Pennsylvania states that the average set was 6 or 7 

 eggs, but in his series there was a range from 5 to 8 eggs in complete 



