342 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1932 



to this move rather than the existence of any special condition that 

 made additional territory necessary. In no case was a male bird 

 found mated with his partner of the preceding year. 



The song sparrow is a home-lover and an individualist. Mrs. 

 Nice concludes that it is " not over fond of flocking, even in the 

 winter, and not of migrating en masse. The same bird may arrive at 

 very different times in successive years, some of the females come 

 before some of the males, and some of the adults come later than the 

 juveniles." 



Baldwin Bird Research Laboratory . — Detailed and extensive 

 studies of the life history of the house wren (Troglodytes aedon) 

 (pi. 5) have been intimately associated with the Baldwin Bird 

 Research Laboratory at Gates Mills, Ohio. Elaborate and highly 

 technical apparatus has been developed to further the investigations 

 and it is a fair statement that no other small bird has ever received 

 the close attention that Doctor Baldwin and his associates have 

 accorded this species. 



Baldwin (1921) had already pointed out that house wrens not 

 infrequently change mates between their first and second broods 

 and, while of infrequent occurrence, had indicated that polygamj'^ 

 was not unknown. The species is unusually abundant in and around 

 the Chagi'in Valley, near which the laboratory is located, and many 

 wrens have returned year after year to nest in the locality. Literally 

 hundreds of young have been banded, but strangely enough very 

 few of these have returned to breed in their natal areas. It is well 

 known that juvenile mortality is very heavy, ornithologists generally 

 accepting the theory that on an average each pair of adult passerine 

 birds will raise but two nestlings to maturity. Nevertheless, since 

 the diiferent species remain practically numerically constant, it 

 would seem that there must be a larger percentage of survival of the 

 young than is indicated by the few return records of yearling birds. 



In an effort to answer this question, an intensive study was made 

 in 1926 and 1927. (Cf. Baldwin and Bowen, 1928.) A laboratory 

 assistant was assigned to the task, and during the two seasons the 

 entire wren population of this large area was under almost constant 

 observation. Most of the nesting birds were repeatedly trapped and 

 handled. "V^Tiile a few birds were captured that had been banded 

 in previous seasons, in almost every instance the record showed that 

 they were adult at the time of banding. The problem as to what 

 becomes of the young birds is still one that challenges the efforts 

 of the investigator. 



In a study to determine the relation between the time that the 

 adult wrens spend at their nesting activities and the time that they 

 spend in seeking food and rest for themselves, Doctor Baldwin and 



