520 



Illinois Natural History Survey Bulletin 



Vol. 23, Art.5\ 



sent between 1 million and VA million 

 pounds of edible game. 



MANAGEMENT 



Management of wildlife resources is 

 basically the maintenance of various spe- 

 cies at any desired population level. To 

 accomplish this objective, use is made of 

 what is known of the life requirements of 

 each species in question. Thus, in the field, 

 pheasants may be provided with more ade- 

 quate winter cover, or quails with brush- 

 bramble thickets adjacent to food areas. 

 If such changes plug the most serious en- 

 vironmental gaps confronting the species, 

 the habitat is improved ; and, in the broad 

 sense, further improvement is attained only 

 when the next most serious gap has been 

 mended. It can be said that game habitats 

 are no better than their weakest environ- 

 mental factor, and that they usually may 

 be improved up to the point where all 

 conditions are optimum, after which intra- 

 specific tolerance, or lack of it, becomes the 

 important factor in population density. 



Our present knowledge of squirrel ecol- 

 ogy, admittedly inadequate, permits some 

 general suggestions for managing fox and 

 gray squirrels in Illinois. 



Habitat Improvement 



Among the more effective means of im- 

 proving squirrel habitats are maintaining 

 favorable food and den tree combinations 

 •through selective cutting and planting, 

 maintaining hedgerows, providing den 

 boxes, protecting against fire and grazing, 

 and supplying feed in winter. 



Forestry Practices. — In that fox and 

 gray squirrels are dependent on woodland, 

 no factor can be more important in their 

 husbandry than the woodland management 

 policy. Fortunately, good forest practices 

 generally lend themselves to good squirrel 

 management, especially in the case of fox 

 squirrels. In fact, a small amount of 

 cutting improves large, unbroken stands 

 as squirrel range, because the openings so 

 made promote the growth of food-produc- 

 ing brambles and shrubs, and hence greater 

 variety in both cover and food resources. 

 Fox squirrels may respond to improve- 

 ments effected by selective cutting within 

 a year or two; gray squirrels only after 

 appreciable shrub growth has appeared. 



Shrub-bordered woodlots or stands provide] 

 variety in food resources, and the shrubs 

 are of value in site protection. Logs and 

 down treetops, or piled brush, have a cer- 

 tain, but unmeasured, attractiveness for 

 squirrels, and their presence in the habitat 

 adds to its quality. 



Slashing, wherein all commercial timber 

 is ruthlessly cut and logged, may — and 

 indeed often does — destroy completely a 

 woodland as a squirrel range. Such cut- 

 ting, followed by fire, may eliminate oc- 

 cupancy even by fox squirrels for 10 to 

 25 years. Likewise, the cutting of all 

 defective trees, to which cavity dens are 

 largely confined, greatly reduces habitat 

 quality, not only for squirrels but for 

 other cavity-denning wildlife. Many de- 

 fective trees are good mast producers. 

 Release and improvement cuttings that 

 result in taking out all or most individuals 

 of such species as mulberry, black cherry, 

 wild plum, hawthorn and wild grape 

 make for food shortage during the spring 

 and summer. It has been observed that 

 one elm and one mulberry per acre in oak- 

 hickory or beech-maple types may represent 

 the difference between good, permanent 

 habitat and that which is deficient for 

 squirrels during the spring and early 

 summer months. The usefulness of mul- 

 berry is noted by Goodrum (1938). 



Naturalness in forest stands, involving 

 a reasonable variety of species, the presence 

 of all age classes, including some defective, 

 cavity-containing trees, and an understory 

 of shrubs and young trees, insures a satis- 

 factory squirrel habitat in almost any part 

 of Illinois, fig. 39. 



Forest practices that result in leaving at 

 least a few oaks, hickories and walnuts in 

 the stand are of the greatest importance in 

 maintaining the squirrel range. Of these 

 three tree groups, the hickories, including 

 the pecan, are, tree for tree, of the greatest 

 value to squirrels. Hickories are gen- 

 erally considered of secondary commercial 

 value for lumber, and a policy of favor- 

 ing them in forest practices creates a con-j 

 flict of interests. However, where hickorj 

 constitutes an appreciable part of the 

 stand, as it does throughout much of the 

 oak-hickory type, it is not necessary tc 

 save every hickory in maintaining gooc 

 squirrel range. Under -such circumstances^ 

 release and improvement cuttings mar 

 well favor the commercially more valuable 



