MONTHLY WILDLIFE RESEARCH LETTER 
Vol. 1, No. 9 
Page 3 
captured, marked, and released on the area in 1958. 
A majority of the sick and dead raccoons found in Illinois have 
had what is believed to be toxic amounts of lead in livers and other tissues. 
In an attempt to learn if paint might be a possible source of the lead, white 
lead has been given orally to a spayed female. The white lead was force-fed on a 
piece of bread as the animal would not eat it willingly. Periodic doses of 5, 
10 , and 20 grams each were given in June through September, with 10 doses totalling 
135 grams given. She still appears to be quite healthy, but it is known that 
concentrations of lead build up slowly in some maranals. Gasoline as a possible 
source of lead is being tested on two other spayed females. 
X-ray photographs of the radii and ulnae of captive raccoons have been 
taken periodically for the past several months. The epiphyseal cartilage in one 
castrated male showed no indications of decreasing in width by 17 months of age. 
In seven intact (not castrated) males the cartilage disappeared at approximately 
15-17 months of age and was accompanied by sexual activity as yearlings. Three 
intact male raccoons kept under similar circumstances in the same colony which 
were not sexually active as yearlings still had epiphyseal cartilage at approxi¬ 
mately 17 months of age. It appears probable that the male sex hormone, androgen, 
is responsible for causing the disappearance of the epiphyseal cartilage in males. 
Some variations are to be expected; one wild male, caught in February, 1957, when 
not quite 1 year of age, was not sexually active until November, 1957, although 
it showed indications of becoming sexually active in July, 1957. Epiphyseal 
cartilage was still present in July, 1958, but it was gone by September, 1958. 
Thus, the epiphyses closed when this raccoon was approximately 27-29 months of age. 
The epiphyseal cartilage of one parous female disappeared when she was 
at least 37-39 months of age. Because the cartilage of three other parous females 
disappeared on multiples of 12 months, i.e., minimum ages of 23-25, 2h, and 12 
months, it appears probable that the epiphyses in female raccoons that breed as 
yearlings close at about 36-39 months of age. 
W-61-R-2 F. Greeley, J. Ellis 
Brood surveys were continued at Neoga during September. Five new 
broods were located, bringing the number of individual broods observed on the area 
to U5, a 33.3 per cent increase over 1957. Forty-nine broods were located during 
the summer at Bellmont, a decrease of 16.9 per cent in the number of broods com¬ 
pared to 1957. 
The last responses for the roadside count of pheasants in August, 1958, 
were received from the rural mail carriers. Of l,l|26 cards mailed out, l,0i|0 
(72.9 per cent) were returned. The cards have been edited, and the results will 
be transferred to IBM punch cards for final calculations. 
A Job Completion Report (61-R-l, Job U) on studies of the role of 
calcium as a limiting factor of pheasants was written during September. Egg-shell 
thickness and ash content of the leg bones were used as a measure of the effect of 
level of calcium in the diet of wild birds. The mean thickness of the shells of 
