118 BULLETIN 195, UNITED STATES NATIONAL MUSEUM 



by the male ; sometimes she may accept the nesting box but disapprov- 

 ing of the nesting material or the way it was arranged by the male 

 proceeds to throw it out stick by stick. Both birds do their part in the 

 building of the final nest, but the male spends more time singing and 

 guarding the nesting territory. 



After the female is busily engaged with her incubation duties the 

 activities of the male are less important since all he does is to sing 

 rather mechanically. Occasionally he spends his time carrying sticks 

 into some nearby box in the pretense of building a new nest, and while 

 doing so he sings his courtship song. In fact, the building of the extra 

 nest has been thought to be one of the manifestations of his peculiar 

 courtship. While so employed he often acquires a second mate while 

 the first is still busy with household duties. 



Nesting. — The house wren stands out preeminently as one of the 

 most eccentric of our birds in the choice of its nesting site. In fact, its 

 choice of a nesting place exhibits such extreme variation that it is 

 difficult to select one that can be considered typical. 



The primitive environment of the house wren was the woodlands and 

 its nesting site the natural cavity of some tree or stump. The nest is 

 seldom exposed, but generally the requirements of the wren demand an 

 enclosure that conceals the nest on all sides except the point of en- 

 trance. These birds have readily adapted themselves to the environ- 

 ment of man reaching a state of semidomesticity. They have availed 

 themselves of houses constructed for their special use or lacking these 

 they have built their nests in various contraptions incidentally pro- 

 vided either inside or outside of buildings. They are not particular and 

 are just as apt to accept an old rusty can in a garbage heap as they are a 

 neatly painted house set in the midst of a beautiful flower garden. 



Innumerable curious nesting places have been reported, a few of 

 which will serve to illustrate their infinite variety. At a sanctuary 

 located on Wallops Island, Va., 24 empty cow skulls found bleaching on 

 the island were hung up or lodged in the trees and shrubbery. Almost 

 immediately 23 of the gruesome skulls were occupied by house wrens, 

 who were quick to accept these unusual nesting boxes (Forbush, 1916) . 

 There are several instances where house wrens have built their nests 

 inside the large paper nests of hornets or wasps that were attached to 

 private or public buildings. Before adding nesting materials the 

 interior of the insect nests were excavated by the industrious birds. 

 This relationship between wrens and wasps was reversed in one instance 

 as illustrated by a photograph taken by R. E. Hart (1941) on the 

 campus of Keuka College, New York. A wren house was taken over 

 by a swarm of wasps and was completely covered except for a small 

 part of the roof, with successive layers of paper layed down by 

 the insects. 



It is not uncommon for the wren to make use of the nests of other 



