MONTHLY WILDLIFE RESEARCH LETTER 
Vol. 3, No. 6 
Page 2 
W-56-R-4 Glen C. Sanderson 
Two manuscripts have been prepared, one giving techniques for estimating 
the ages of young raccoons during the summer and for separating both females and 
males into two age classes during the hunting and trapping season. The other 
manuscript also concerned aging but is based on the lens of the eyes. 
The mean birth date for 17 litters of raccoons conceived in the wild was 
April l6j the earliest birth date was March 9 and the latest June 10. Thus, the 
mean birth data can be used for estimating the age of raccoons less than 1 year of 
age if body weight is not available. 
Observed growth rates indicate that body weight will permit an estimate 
of age in voung wild raccoons up to 7.0 pounds with an error believed to be no 
more than ~ 2 months. 
Studies of epiphyseal cartilage plates in the radii and ulnae of captive 
and wild raccoons of known ages indicate that, during the hunting and trapping 
season in Illinois, epiphyses may be used to separate males into two age groups. 
Those with broad epiphyses are older. Epiphyses and other structures may also be 
used to separate females into the same two age groups during the hunting and 
trapping season. All parous females (those with placental scars in the uterus) 
and all nulliparous females with thin or closed epiphyses are more than 1 year of 
age. Nulliparous females (those with no placental scars) and with broad epiphyses 
are less than 1 year of age. The latter animals did not breed during the first 
mating season following their birth. 
In the raccoon, the lens will indicate the month of birth for individual 
raccoons up to approximately 12 months of age. The lens may be used to determine 
the general age composition of a population, but, because of great individual 
variation, it cannot be used to determine the age of individual animals that are 
older than 12 months. 
W-61-R-3 F. Greeley, J. Ellis 
An experiment to measure the combined effect of the amounts of calcium 
and phosphorus in the diet on laying hen pheasants was completed on June 1. The 
diets, containing various percentages of calcium and phosphorus. Table 1, were fed 
from March 8 to June 1. Last year it was found that hens lost a greater percentage 
of initial body weight, during the laying season (April 13 - June 4), on low calcium 
diets than on high calcium diets. In I960, although some individual hens lost 
weight during the experiments, all groups showed an average gain in weight, Table 1. 
The gains were less, however, on low amounts of calcium than on high amounts of 
calcium. The effect of phosphorus on weight changes was not as evident although 
when the diets contained an adequate amount of calcium the weight gains were 
greater at high than at low levels of phosphorus. Hens in the wild, in a calcium 
or phosphorus deficient area, may lose more weight than is normal and have higher 
