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Illinois Natural History Survey Bulletin 



Vol. 23, Art. 5 



a well-defined direction; and "Dispersal," 

 which deals with the phenomenon of 

 spread or "shuffle" in squirrel populations, 

 especially in the fall prior to the breeding 

 season. 



Local Movements 



Both fox and gray squirrels are usually 

 considered sedentary species, although the 

 latter, according to some authors, are 

 subject to irregular migrations, discussed 

 below. As has been reported by Seton 

 (1928), Baumgartner (1938, 1943^0, 

 Goodrum (1940) and Allen (1942, 

 1943), local movements in both species of 

 squirrels appear to be caused mainly by 

 food conditions. In the course of a year, 

 fox squirrels, apparently in foraging, may 

 cross woodland or open fields for a dis- 

 tance of 2 or 3 miles. Gray squirrels, 

 where favored by continuity of forest 

 cover, may travel equal if not greater dis- 

 tances. The homing instinct of this spe- 

 cies was studied by Hungerford & Wilder 

 (1941), who reported returns in 6 of 15 

 animals, the greatest distance being 2.8 

 miles during a period of 4 weeks. 



Squirrels shift readily from one local 

 food area to another. On the Chautau- 

 qua National Wildlife Refuge, fox squir- 

 rels deserted one area after another as 

 specific foods in other areas became avail- 

 able. They frequented the elm lowlands 

 from late February into July, when elm 

 buds and seeds, and later mulberries, sup- 

 plied staple foods; they raided adjacent 

 cornfields from midsummer until fall ; 

 and they used upland oak-hickory areas as 

 main foraging grounds during the fall and 

 winter. These shifts, however, at no time 

 involved travels of more than a few 

 hundred yards, and in no sense did they 

 take on the usual characteristics of mi- 

 gration. 



In one wooded area on the Chautauqua 

 Refuge containing mature oaks, pecans 

 and hickories, in addition to elms, maples 

 and other riverbottom species, seasonal 

 shifts in the squirrel population (all fox 

 squirrels) were much less distinct than 

 those mentioned in the foregoing para- 

 graph. Indeed, day-to-day travel here 

 seemed to be confined to a small area, 

 usually not more than a few acres, and 

 often the vicinity of one or a small group 

 of food trees. The annual range of the 



resident population covered only about 150 

 acres. 



During the young-rearing period par- 

 ticularly, females seemed to confine their 

 movements to the vicinity of their brood 

 sites, which numbered from one to several. 

 In both species local movements were most 

 extensive during the fall. 



When not disturbed by overhunting, 

 fire, drought or lumbering, individual 

 squirrels may spend an entire year or more 

 in the vicinity of a given nest tree. Allen 

 ( 1942) reported an example of a Michigan 

 fox squirrel female that used a red maple 

 as headquarters continuously from Oc- 

 tober, 1937, at least until observations 

 were terminated in December, 1939. 



Seton (1928) stated that a gray squirrel 

 may live its entire life on a 100-acre plot. 

 Goodrum (1940) considered the home 

 range of this species to be 200 yards or 

 less, but he believed that some individuals 

 may cover 4 or 5 miles during the course 

 of a year. Middleton (1930) intimated 

 that gray squirrels in Great Britain seldom 

 travel more than 100 yards from head- 

 quarters, but also stated that the species 

 extended its range 35 miles in 5 years. 



Migration 



No evidence of migration in fox squirrels 

 was observed in this study. Baumgartner 

 (1938) writes: "General and regular mi- 

 gration of the fox squirrel is unknown." 

 Allen (1943) states: "Fox squirrels have 

 seldom been observed in mass movements 

 similar to those of the gray, which was 

 known in early daj's as the 'migratory 

 squirrel.' " There are numerous reports 

 of mass movements or migrations of gray 

 squirrels covering considerable distances; 

 in these movements the animals were not 

 deterred even by the formidable Avidths of 

 the Hudson, Ohio or Mississippi rivers. 

 Seton (1928) associated this phenomenon 

 with food shortage, overpopulation and 

 cyclic influences. Chapman (1936) at- 

 tributed it mainly to the first two reasons. 

 Jackson (1910, 1921) cited two instances 

 in which numbers of the gray squirrel, in 

 one case possibly because of a food short- 

 age, swam the Mississippi River from Wis- 

 consin to enter Minnesota. Goodwin 

 (1934) reported an extensive migration 

 in the New England states in 1931 

 and 1933. Osgood (1938) reported a. 



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