September, 1945 



Brown & Yeager: Squirrels in Illinois 



471 



These numbers represented little more 

 than one-half of 1 per cent of the total 

 number of animals collected, but they 

 gave, of course, no true index of crippling 

 loss, which hunters' questionnaires indi- 

 cate are much higher, table 23. Animals 

 showing imbedded shot but healed wounds, 

 or missing toes probably due to shooting, 

 were not counted among the cripples. In 

 tw^o cases, one in each species, bones of a 

 hind leg were so badly shattered that re- 

 covery was improbable. Some seriously 

 wounded squirrels undoubtedly make their 

 way to cavities or nests, from which they 

 probably never emerge. In all except one 

 case, shotgun pellets were the cause of the 

 crippled condition observed. A fox squir- 

 rel that recovered from a severe wound is 

 sliown in fig. 7. 



Molt and Color 



Fox and gray squirrels molt once a 

 year, the two species having similar molt- 

 ing characteristics. The molt consists of 

 two phases, the first involving the body 

 and the second the tail. Males molt be- 

 fore females, beginning in the spring and 

 concluding the process during the summer. 

 Females appear to molt at any time be- 

 tween April and September, after their 

 last young of the year have been born. 

 Adult males and spring juveniles ordi- 

 narily molt before adult females, especially 

 those producing second-season or summer 

 litters. These adult females usually com- 

 plete the molt in September. 



Molting in both fox and gray squirrels 

 requires 3 to 4 weeks. Progress in the 

 body phase is from nose to tail ; on the 

 tail, molting begins at the distal end and 

 progresses anteriorly to the base of the 

 tail. In most individuals there is a defi- 

 nite line of demarkation between the new 

 and old hair. When such a line is not 

 present in molting animals, new hair is 

 being replaced over a relatively wide area, 

 the old and new hair tending to blend. 



Few of the colf)r patterns ordinarily 

 found in squirrels were encountered in 

 Illinois during the course of this study. 

 One very reddish female fox squirrel w-as 

 shot that may have been an example of 

 erythrism. This was a mature animal, 

 taken on August 7, 1942, while "cutting" 

 a hickon,' nut. She was host to a very 

 large ascarid. No distinct albino or mel- 



anistic individuals were taken. However, 

 albino gray squirrels occur in considerable 

 numbers in Olney, where they are said to 

 have increased from an albino pair re- 

 leased some years ago. Melanistic squir- 

 rels have been reported from Ogle County 

 and other northern Illinois localities. In 

 an early report, Kennicott (1857) stated 

 that of 50 gra>- squirrels killed near Rock- 

 ford, Illinois, all were black. During the 

 pioneer period, black squirrels were com- 

 mon in Michigan (Allen 1943), Indiana 

 (Haymond 1869, Hahn 1909) and in 

 other states. One adult male gray squir- 

 rel trapped in Pike County, February 25, 

 1941, had reddish thoracic hair and black 

 abdominal hair. A juvenile male fox 

 squirrel with blue eyes was trapped in 

 Pike County, February 8, 1942. Baum- 

 gartner (1943/*) reported nine different 

 color patterns in Ohio fox squirrels, in- 

 cluding melanistic, near albino, brown- 

 tail, and variations of black and red or 

 rufus. 



PARASITES AND DISEASES 



Several papers dealing with the para- 

 sites of squirrels, particularly fox squirrels, 

 have been published. Katz (1939) 

 brought most of this information together. 

 Harkema (1936) studied the parasites of 

 53 gray squirrels in North Carolina, find- 

 ing one species of tapeworm, one of round 

 worm, three of mites, two of lice and one 

 of flea. Chandler (1942) recently re- 

 ported on the helminth worms of tree 

 squirrels in southeast Texas ; and Graham 

 & Uhrich (1943) published on the ex- 

 ternal and internal parasites of the fox 

 squirrel in southeastern Kansas. Baum- 

 gartner (1940) and Allen (1942, 1943) 

 discussed briefly the parasites and diseases 

 of fox squirrels in Ohio and Michigan, 

 respectively-; and Goodrum (1940) re- 

 ported similarly for gray squirrels in 

 Texas. The most prevalent parasites re- 

 ported by all these authors were mange 

 mites. No diseases of endemic nature 

 other than mange were reported. 



Most squirrels studied during 2 years 

 of field work in this investigation were 

 examined for mange, and for ticks and 

 other external parasites. The same spe- 

 cies of parasites were found to occur on 

 both fox and gray squirrels. Mange 

 (caused by Sarcoptcs sp.) occurred to a 



