736 U.S. NATIONAL MUSEUM BULLETIN 23 7 pabt 2 



Behavior. — The grasshopper sparrow is a secretive bird, difficult to 

 observe. It seldom flies, but runs ahead of the searcher through the 

 grass and flushes only when hard pressed. As WiUiam Brewster 

 (journal) describes it: "when flushed the sparrows rise swiftly and 

 vigorously, twisting a little * * * the flight then becomes steady and 

 direct and is performed in long, regular undulations, the wings being 

 vibrated rapidly." He adds: "On the ground they both run and 

 hop." Witmer Stone (1937) notes that in flight the bird "turns to 

 one side or the other like a snipe." Simmons (1925) writes that when 

 flushed the western grasshopper sparrow rises "in a zig-zag flight for 

 a few yards" and then "dives back into the weeds. * * ♦ in open 

 fields, flight is extended and rapid." 



The bird perches in a peculiar crouched position, as if ready to 

 dart off in an instant. 



D. J. Nicholson comments on the colonial nature of floridanus: 

 "They breed in small colonies — three or four to a dozen pairs. These 

 colonies are very local and are not found everywhere over this vast 

 prairie, many apparently suitable spots being unoccupied." 



These same words might well apply to the eastern and western 

 grasshopper sparrows as well, for they show the same colonial nature 

 and fluctuate considerably in abundance from year to year. 



One cause of population changes might be attributed to grassland 

 management practices. On my study area, for example, the fields 

 during the early part of the study were run down and supported a 

 poor growth of timothy, alfalfa, and red clover. From 1944 on, the 

 fertility of the fields increased considerably and the grass mixture 

 was changed to a thick, vigorous growth of alfalfa, ladino clover, 

 and brome grass {Bromus inermis). The grasshopper sparrows in 

 the area settled in hay and abandoned fields where the vegetation 

 was not so heavy. 



Oscar Root (1957, 1958, letter), who kept a long-time record of 

 local population fluctuations on a level, artificially drained airport 

 of 100 acres at North Andover, Mass., found the grasshopper sparrow 

 populations there built up to highs, followed by severe reductions in 

 numbers the following year. He believed mowing the grass on the 

 area prior to his counts reduced the population. However, when 

 mowing was postponed to allow completion of nesting by the sparrows, 

 the population still remained low. He states that certain areas always 

 productive in the past were without grasshopper sparrows, though 

 in prime shape and undisturbed. 



The birds about Concord, Mass., have shown a similarly fluctuating 

 pattern of abundance through the years (Griscom, 1949). 



