MONTHLY WILDLIFE RESEARCH LETTER 
Vol. 2, No. 7 
Page 2 
R. D. Lord 
W-42-R-9 
was 27.8 per cent and that of adults was 17.5 per cent. This error can be crucial 
in estimating the probable population later in the year because it is the large 
juveniles that will breed and contribute a significant proportion of the annual 
crop. 
The July issue of the Journal of Wildlife Management contained two articles 
originating from this project. One was, "The Lens as an Indicator of Age in 
Cottontail Rabbits" and the other a joint report with Ronald Labisky, was,"A 
Flexible, Plastic Eartag for Rabbits." 
W-55-R-4 
F. Bellrose 
This project was inactive during July. 
W-56-R-4 G. Sanderson, K. Johnson 
Field work was continued on the raccoon and wood-duck project in the 
Havana area through the duck nesting season. Twenty-nine per cent of the natural 
cavities were used by wood ducks. A similar study in the same region indicated 
that 51 per cent of the cavities were used by wood ducks in 1939 and 1940. 
Where a direct comparison could be made, 44 per cent of the nests in 
natural cavities were successful during the current study and 49 per cent during 
the 1930-40 study. When both natural cavities and nest houses were present on 
the same area, wood ducks showed a slight preference for natural cavities. 
Raccoons were responsible for 36 per cent of the nests destroyed during 
the two years of the current study, but they cannot be said to be the one factor 
limiting wood-duck nest success; the total success was about the same as during 
the earlier study when raccoon populations were at a lower level than they are 
now. During the earlier study, raccoons destroyed 37 per cent of the wood duck 
nests in wooden boxes. Fox squirrels destroyed 23 per cent of the unsuccessful 
nests in natural cavities. 
No nests were destroyed by raccoons in the trees banded with "Tanglefoot." 
During July, 57 raccoons were live-trapped 85 times on the Allerton Park 
study area. Thirty-four were young-of-the-year: 20 females and 14 males. Nine 
of the 12 females had been captured previously, seven of them in 1956 and two 
in 1957. 
Forty-six opossums were live-trapped 82 times. Thirty-one were young-of- 
the-year: 15 females and 16 males. One of the two adult males was first caught 
in 1958, the other this year. Six of the 13 adult females were recaptures, 
including two that were first caught in 1958 and four in 1959. 
Eleven of the 13 adult females were carrying 102 pouch young. The litters 
ranged from six to twelve young each and averaged 9.13. All pouch young were 
toe-clipped. Of the 68 pouch young for which sex could be determined, 40 were 
