36 BULLETIN 149 7, U. S. DEPARTMENT OF AGRICULTURE 
basis of the 7-year cycle, they should have, and are reported to have 
decreased in numbers during 1925. When they are as abundant as 
they were in Minnesota in 1923 and 1924, it is a question whether 
planting operations should be undertaken except on the open sandy 
soils. The removal of the closed season on snowshoe rabbits should 
tend to control them somewhat, but they are not much hunted in any 
season in a region which abounds in more desirable game. The use 
of poisoned bait would probably be effective in controlling them 
locally on areas occupied by plantations. 6 
A thoroughly satisfactory solution of the rabbit problem has not 
been worked out. If it is assumed that rabbits will be sufficiently 
abundant to do serious damage at six to seven year intervals, it is 
desirable to do as much planting as possible in the year in which they 
die off in order that as many trees as possible may attain heights of 
over 3 feet and have their tops beyond the reach of the rabbits before 
they are seriously attacked. The period is not likely to be sufficiently 
long, unfortunately, to avoid much of the loss, for usually only a few 
of the trees in plantations of northern white or Norway pine or 
spruce are more than 3 feet high at 6 or 7 years of age. 
Since the rabbits seem to avoid open country, trees planted in the 
open, in clearings, or where there is little or no brush, are less likely 
to be injured. An experiment at the Cloquet station showed the 
damage from rabbits to be much more severe under dense jack pine 
15 years old than under a moderately dense 35-year stand or an open 
75-year stand. In another experiment, rabbit damage was heavy on 
a site characterized by a dense growth of alder, willow, and aspen, and 
negligible on a site with a cover of sweet fern (89). 
Deer, porcupines, mice, and red squirrels all occasionally damage 
forest plantations. Where deer are abundant, as in Itasca Park, 
they nip the needles of the pines. Porcupines sometimes girdle the 
northern white pines, usually up in the crown where the bark is 
tender ; and if the girdling is complete the top dies. They may also 
kill the small trees, although evidence of this has not been observed. 
Mice have been known to girdle the trees in young plantations near 
the ground line under the snow. This form of damage, however, 
has not been evident in the Lake States. In a few plantations the 
buds, particularly of Norway spruce, had been eaten off. Grosbeaks 
in Michigan have been known to do this. Ked squirrels also eat 
the buds and cut off the small twigs. 
Further information of what measure to take to combat damage 
by wild animals or rodents may be obtained from the Bureau of 
Biological Survey, United States Department of Agriculture, Wash- 
ington, D. C. 
Goats, sheep, cattle, hogs, and horses should be kept out of forest 
plantations, to prevent damage both from their browsing the foliage 
and twigs and from trampling. Only a few of the plantations in 
6 The Bureau of Biological Survey (20) has suggested the scattering of poisoned bait in 
early spring a few hours before sunset along the rabbit trails and in openings. The rec- 
ommended poison mixture consists of 1 ounce strychnine sulphate, 1 teaspoonful saccharin, 
and V 2 cup gloss or laundry starch in 1 quart of water. The strychnine and saccharin 
are dissolved in the water by boiling, the starch, already softened with cold water, is 
added, and the boiling is continued until the solution thickens. Fifteen pounds of twigs 
of native brush — aspen, for example — cut in 2 or 3 inch lengths, are coated with the 
mixture, which is then ready for immediate or later use. There are serious objections to 
this method, however, in a region where desirable game animals would also suffer from 
the distribution of the poison. 
