GRASSHOPPER SPARROW 729 



The territorial "grasshopper" songs usually are delivered from the 

 highest perches in the territory. These may include a clump of 

 grass, an alfalfa stalk, a tall weed, a small bush, fence post, utility 

 wire, tree, or farm equipment left in the field, hay cocks, or grain 

 shocks. The birds appear restricted to low perches only by their 

 habitat, and use low ones simply because no higher ones are available. 

 This was demonstrated experimentally. When a wooden stake tall 

 enough to stand two feet above the grasstops was placed in a bird's 

 territory, the bird claimed it within minutes. When a still higher 

 perch was introduced the next day, the bird abandoned the first for 

 the new, higher perch. 



Song perches are clustered about certain singing areas, usually near 

 the periphery of the territory, apart from the nesting areas. Among 

 the birds I have studied, singing perches were from 165 to 412 feet 

 from the nest. Their position may be influenced by row crops in the 

 territory when grasshopper sparrows then confine their singing 

 perches to the vicinity of grass plots. 



The size of 22 territories plotted on my study area ranged from 1 .2 

 to 3.3 acres; 11 were between 1 and 2 acres, 9 between 2 and 3 acres, 

 and 2 were over 3 acres. Their average size was 2.03 acres. Kendeigh 

 (1941) reports the average size of 6 territories was 3.4 acres. 



Territorial boundaries are maintained rigidly during the periods of 

 territorial estabHshment, nest building, and incubation. After the 

 young hatch, territorial defense declines and considerable movement 

 of birds into other territories occurs. The movement is often initiated 

 by young birds just able to fly, that flutter into adjoining territories 

 where the parents follow in answer to the feeding caU. 



Prior to second nesting, territorial defense increases sharply for 

 2 to 3 days. The males sing the "grasshopper" song and flutter their 

 wings. Territorial boundaries may be shifted in response to dis- 

 turbances made by harvesting of hay and small grains. In one 

 instance a male grasshopper sparrow shifted his territory for the 

 second nesting to include the eastern half of his neighbor's territory. 

 The hay on this portion had been mowed early, and new growth 

 afforded cover lacking in the original territory. The neighboring 

 male in turn took over the western half of the first male's old territory. 

 In the end both birds had new growth and newly mowed hayfields in 

 their respective temtories. Interestingly, these two birds occupied 

 approximately the same territories the following year. Another male, 

 whose territory was bisected by a strip of field corn, took over a 

 corner of his neighbor's territory when the increasing height of the 

 corn walled off the lower half of his own territory and made it useless. 



