WESTERN HENSLOWS SPARROW 779 



PASSERHERBULUS HENSLOWII HENSLOWII (Audubon) 



Western Henslovv's Sparrow 

 Contributed by Jean W. Graber 



Habits 



Henslow's sparrow is a grassland species occupying meadows or 

 marshy openings in the woodlands of central and eastern United States 

 and southern Canada. A shy, unobtrusive, and secretive little bird 

 that tends to run when disturbed instead of flying, it is consequently 

 hard to find and difficult to observe in the field. When Audubon 

 discovered the first specimen in Kentucky just across the Ohio River 

 from Cincinnati in 1820, he painted the bird and named it (1829) for 

 his friend the Reverend John Steven Henslow, professor of botany at 

 Cambridge University, England. 



The nominate western subspecies differs from the Atlantic coastal 

 race, susurrans, in being generally lighter, with less yellow at the wing 

 bend, heavier black streakings and less chestnut on the back and 

 scapulars, and a thinner bill. The Appalachian mountain chain may 

 have been the isolating mechanism in the formation of the two races, 

 each of which has apparently expanded its range since the opening of 

 North America by man. As A. Sidney Hyde (1939) points out, 

 "The primeval forests which extended almost unbroken from western 

 Indiana to the salt marshes of the Atlantic coast must have originally 

 offered little to induce colonization by this bird. * * * Widespread 

 clearing of the forests has made more habitat available * * *. Recent 

 marked increases in abundance are reported from Ohio, southern 

 Michigan, and Ontario. * * * many of the known breeding colonies 

 are so situated as to lead to the belief that watercourses serve as im- 

 portant migration highways for the species. In the Appalachian 

 highlands the valleys of the Merrimac, Connecticut, Hudson, Delaware 

 and Susquehanna rivers appear to have a more than casual relation- 

 ship to the locations of colonies reported from northern New England, 

 New York, and Pennsylvania." 



Throughout its summer range the western Henslow's sparrow oc- 

 cupies weedy prairies and meadows, and neglected grassy fields and 

 pasturelands, which are often dotted with low shrubs or bushes. 

 The vegetation it inhabits may be rather irregular in height and den- 

 sity, or fau'ly uniform; the ground cover is usually quite dense and at 

 least a foot or two high. In northeastern Kansas the species occupies 

 the lower, moister depression in upland, mid-grass prairie. Hyde 

 (1939) notes the dominant plants in its southern Michigan habitat to 

 be cord grass {Syartina pectinata) and shrubby cinquefoil (Potentilla 

 jruticosa). It seems to prefer low-lying, damp situations, but it may 



