Vol. 14, No. 1 
Page 2 
At the beginning of this research in 1962, 9*3 percent of the land on the 
Sibley Study Area was in hay; by 1970 this percentage had dwindled to about 
2.6, with indications of further decreases in the future. Thus, it is possible 
that roadsides, only 1.3 percent of the study area, will constitute the 
largest segment of potential nesting cover for pheasants. 
In 1970, the 149.2 acres of managed seeded roadsides increased the 
amount of land in hay on the Ford County Management Unit (FCMU) from 402 
to 551*2 acres, an increase of 37*1 percent. (At the same time, however, 
the amount of unseeded roadside cover on the area was reduced by over 90 
percent.) If the proportion of the total land area in hay continues to 
decline, the contribution of the managed seeded roadsides to the total 
acreage in hay will increase. If, eventually, the acreage in hay on farms 
makes up only one percent of the land area on the FCMU (102 acres), the 149.2 
acres of seeded roadsides will increase the total hay acreage by over 146 
percent. Admittedly, increasing 402 acres of hay by 37 percent, or 102 acres 
by 146 percent, provides only a small amount of hay for an area of this size. 
Nevertheless, under such circumstances, the contribution of seeded roadsides 
to the nesting-cover complex could be substantial. Had 90 percent of the 
roadside acreage on the Sibley Study Area been seeded in 1970, the amount of 
hay on that 36 -square-mile area would have increased from 610 to 923 acres, 
or 51 percent. 
3 . Ecology and Management of Squirrels C. M. Nixon 
Female gray squirrels implant fewer fertilized ova during their first 
estrus than during subsequent breeding periods. Placental scar counts from 
46 yearling females showed a mean and standard error of 2.54+ 0.11 scars. 
Similar counts for single litters from 98 adult females provided a mean and 
standard error of 3*^+3 + 0.09 scars. This difference is statistically 
significant (P<0.01). 
The reduced implantation in yearling breeders can occur as a result of 
either a lower rate of ova release or a higher rate of ova mortality between 
ovulation and implantation, compared with rates for older females. Data 
tending to support either of these assumptions are lacking for the gray squirrel, 
but data collected from other species of rodents tend to support the assumption 
of a lower rate of ovulation for yearling female gray squirrels. 
The maturation and release of ova in mammals is controlled by the 
pituitary, through release of the follicle-stimulating hormone (FSH). 
At least in the domestic rabbit, pituitary weight and the amount of FSH 
released, vary directly with body weight. If such a relationship occurs in 
the gray squirrel, yearling females, which average 1 to 3 ounces lighter in 
body weight than adult females, may produce lesser amounts of FSH than do 
the adults, thus resulting in fewer mature ova during their first estrus. 
