Vol. h, No. $ 
Page 2 
Six new transmitter radios for rabbits were constructed during the month 
and much work was done on improving the receiver, A test was made of the trans¬ 
mitter adapted for use on mallard ducks (in cooperation with Frank Bellrose); 
the range achieved was 22 miles, 
W-5>6-R-£ R, J, Ellis, T, U, Meyers, G. C, Sanderson 
Since 19!?8 raccoon predation on wood duck nests on the study areas has been 
combated by placing a band of "tanglefoot" around the tree and below the nest 
cavity. This year a band of metal lU inches wide was substituted for "tanglefoot" 
on 30 trees. The metal is less expensive and possibly more effective than 
"tanglefoot." 
Five cavities located in trees banded with metal bands were used by wood 
ducks for nesting. Fox squirrels destroyed three of these nests, but raccoons 
destroyed none. The cavities in the banded trees probably are more accessible 
to squirrels than to raccoons because, although the cavities may be protected 
from below, they are not protected from above. An animal entering the crown 
of a banded tree could approach the cavity from above. Because squirrels are 
more agile than raccoons in moving on branches from one tree to another, they 
probably are less affected by protective devices below the cavities. 
This year 126 natural cavities judged to be suitable for wood duck nesting 
were located on the study areas. Wood ducks nested in 22 of these. One of 
the nests hatched, eight are being incubated, seven were destroyed by fox 
squirrels, five were destroyed by raccoons, and one was destroyed by wind damage 
to the tree. 
During May, raccoons weighing approximately 8 pounds were found in tree 
cavities with entrances too small to admit normal-sized adult raccoons. The 
greater number of small raccoons this year appears to be a result of a delay in 
the i 960 breeding season which was caused by abnormally severe winter x^eather 
during much of the raccoon’s normal breeding season in I960. 
Data collected during the past six breeding seasons in the northern half of 
Illinois indicate that most raccoons are born during April in this section of 
the state. The mean date of birth for 19 litters conceived in the wild, six 
of which were born in captivity, was April Ik; the earliest date of birth was 
March 9 and the latest June 10. Birth dates for young not born in captivity 
were estimated by measuring the uterine swellings and comparing their sizes with 
the sizes of uterine swellings of embryos of known ages. 
The mean date of birth for 11 litters conceived and born in captivity, in 
Urbana, Illinois, was April 2iu The earliest date of birth for a litter con¬ 
ceived in captivity was March 16, and the latest was June 3. 
