WESTERN HENSLOWS SPARROW 781 



In fields inhabited by colonies of Henslow's Sparrows the numbers of birds an 

 acre maj' run rather high, but over any extensive area, taken as a whole, the popu- 

 lation will be low because of the large amount of uninhabited land. In one nine- 

 acre field (Field 3) at Anderson four pairs nested in 1934. In 1936 it was estimated 

 that seven males had their territories in this field, in which four nests (one deserted) 

 were found before June 10. In field there were about 40 acres of habitable 

 territory, which held about thirty to forty singing males in 1934. A similar 

 density is reported from Mahoning County, Ohio, by Vickers (190S: 150-52), wlio 

 found from nine to twelve males in a fourteen-acre field. ITennossey (1916: 115) 

 found from forty to sixty birds (he does not say pairs) in an area of about 160 

 acres in southern Michigan, near Albion. A record for density is reported from 

 Iowa by Anderson (1907: 317) on the authority of G. H. Berry, who reported ten 

 pairs breeding in a field of hazel and blackberry of about one-half acre in extent. 



Sutton (1928a) found about a dozen pairs in a 10-acre area of dense 

 grass in Pymatuning Swamp in northwestern Pennsylvania. 



Courtship. — Little has been observed of the courtship of this rather 

 secretive species. Hyde (1939) writes of it as follows: 



Aside from the increasing frequency and volume of song, the first courtship 

 behavior was noted on the afternoon of May 9, 193G. A singing bird that had 

 been changing his perch frequently, dropped to the ground and was joined by 

 another individual as the call of intimacy was uttered. Presently the male was 

 seen with a piece of dry grass in his mouth, hopping among the hummocks. He 

 soon dropped the grass and began singing feebly from the ground. The female 

 remained concealed, except at intervals when one bird closely following another 

 llitted above the grass for an instant and then dropped back, the actions being 

 punctuated with frequent renditions of the call of intimacy. No trace of a nest 

 could be found. 



Early the next morning at the same place a singing male with a mouthful of 

 dried grass alighted on a hummock near another bird. Dropping the grass and 

 fluttering his wings continually the male proceeded over and among the hummocks. 

 He appeared to be taking the female on a tour of the area, indicating to her each 

 possible nesting site by violently fluttering into it. 



A male was seen copulating with a female perching in open view on a bush, and 

 holding dead grass in her bill, on July 23, 1934. After the second union both 

 birds dropped into the grass. The male appeared again, flying with rapid vibra- 

 tions of the wings characteristic of many birds just subsequent to copulation. 



A pair of birds were apparently mating under concealment of the grass on Juh' 

 11, 1934. The male, at first singing, began to chase the other bird, and both 

 disappeared in the vegetation. Whenever they reappeared their wings were 

 fluttering or vibrating characteristically. Finally the female ate a caterpillar 

 she had been holding all the time, and the male began singing in a subdued voice. 



Though the species is essentially monogamous, Hyde observed 

 copulation between a mated female of one territory and the male of 

 an adjacent territory. 



Nesting. — The well-concealed nest is always placed on or near the 

 ground. A few nests have been found actually sunk into depressions 

 in the ground. Usually it is built at or near the base of a thick clump 

 of grass with its bottom two or three inches above the ground. The 

 grass often arches over the nest so as to form a partial roof. Some 



