116 BULLETIN 195, UNITED STATES NATIONAL MUSEUM 



Spring. — The first arrivals of the house wren make their appearance 

 along the southern limits of the breeding range during the latter part 

 of March, but it is not until the middle of April that tliey become 

 common. Certain individuals remain on the southernmost wintering 

 grounds until the second week of April. In Florida a series of 8 

 years of records of birds last seen in the spring range from April 

 12 to April 22, an average date of April 17. The first house wrens 

 arrive in New England and a corresponding latitude in the Midwest 

 during the last week of April or early in May, but it is not until 

 the middle of the month that the nesting activities are in full swing. 

 At Hillcrest, Ohio, according to Kendeigh (1941) , who made observa- 

 tions on the time for beginning of the nesting activities of 186 males 

 and 165 females, "The median date for all the males to begin nesting 

 activities is May 11, altliough the median date for the first male 

 activity is May 1, and for the Za^^esiJ male to begin activity * * * jg 

 June 22. Females average later, the corresponding three dates being 

 May 20, May 11, and July 1." Kendeigh continues: 



Although first-year birds may be among the first to arrive in late April and 

 early May, adults of two or more years of age make up a far greater percentage 

 of the migratory population at this time than they do later in the season. Females 

 arrive about 9 days later than the males. 



Adult males that have previously nested almost invariably return to the same 

 territory that they formerly occupied, or they establish a new territory adjacent 

 to it. The return of adult females to their former nesting areas is almost as 

 regular. 



With young birds hatched the preceding season, there is a marked tendency to 

 scatter in all directions, although they occur in greatest relative numbers in the 

 vicinity where they were hatched. 



TerHtory. — As soon as the male appears on the breeding ground 

 his arrival is announced by the territory song. The male isolates 

 himself and establishes himself in a definite area. Territory is im- 

 portant as a means by which birds become paired and mated and an 

 insurance for adequate nesting sites and food supply. According to 

 Kendeigh (1941) — 



the process of courtship and mating can scarcely be separated in the house 

 wren from the phenomena of territory, as they are so vitally interwoven and 

 intrinsically related. 



Territory is established and defended chiefly by song. * * * The "territory 

 song" of the house wren is but little different from the "nesting song," and both 

 songs announce to other birds that the territory is occupied. [The territory song 

 is also an advertisement of the male's presence to females, and of inducement 

 to the female to enter a particular male's territory in preference to the territory 

 of some other male.] 



The presence of a female is a distinct incentive to song. The male will give 

 his territory song over and over again, day after day, in a purely mechanical 

 manner until a female comes into view. Not really until then does he show 

 emotional excitement. The song is given more energetically, the mating song 

 is interspersed and males from adjoining territory may tune in. Competition 



