cutover areas. Deermice commonly associ- 

 ated with loss of Douglas fir seed were 

 found to have a breeding season extending 

 from March to October on the experimental 

 area. Juveniles were found in the population 

 from July through November with a peak in 

 October when about 57 percent of the deer 

 mice were young-of-the -year. The maxi- 

 mum number of embryos per female was 9 

 and the average was 5. 



The role of red squirrels in forest re- 

 generation was investigated on Cedar Island 

 in Flathead Lake, Montana. A mark-and- 

 release study showed that approxinriately 50 

 percent of the fall population of red squir- 

 rels on the Island was composed of animals 

 2 years old or older. There appeared to be 

 a poor survival of young, for 7 out of 10 

 juveniles marked in midsummer disap- 

 peared by November. The squirrels began 

 clipping green Douglas fir cones in July and 

 continued through the fall. Clipping seemed 

 to be concentrated on thrifty, heavy seed- 

 bearing trees, and by November few cones 

 remained on the trees frequented by red 

 squirrels. 



Other mammals. --A 12-year study of a 

 Lower Michigan jack pine plantation re- 

 vealed that 22 out of 25 trees within deer 

 and hare exclosures were of crop quality, 

 whereas on unprotected plots only 1 of 7 

 made a crop tree, most of the remainder 

 being multistemmed or badly deformed. 

 The average height of the protected trees 

 was 13.5 feet, compared with 7.5 feet for 

 unprotected trees. Tree survival as re- 

 corded in 1961 was 96 percent in the 

 exclosures and only 44 percent in the un- 

 protected plots. Similar results were ob- 

 tained in a red pine plantation in the 

 Tamarack National Wildlife Refuge in 

 northwestern Minnesota and in a planted 

 jack pine stand in the Superior National 

 Forest of Minnesota. 



Among the mammals studied by the Co- 

 operative Wildlife Research Units were 



w^^r 



Severe deer browsing produced multiple-stemmed and 

 badly deformed jack pine in Lower Michigan. 



(Photo by Laurlts Krefting.) 



antelope; black, grizzly, and polar bears; 

 bison; mule and white-tailed deer; elk; 

 javelina; moose; bighorn and Dall sheep; 

 such fur animals as beaver, fisher, arctic 

 fox, marten, mink, muskrat, river otter , and 

 ringed seal; small game mammals including 

 the snowshoe hare, cottontail, and swamp 

 rabbits, and the gray squirrel; and others, 

 including bats, the bobcat, coatimundi, 

 porcupine, cotton rat, and ground squirrels. 

 Mention is made here of only a few of these 

 studies. 



Over a 3-year period, Montana Unit per- 

 sonnel have made a total of 1,809 different 

 observations of marked, and unmarked but 

 recognizable, grizzly bears. Data from 

 field observations and recaptures indicate 

 a high cub mortality during their first 

 winter. The cub -yearling ratio has been 

 91 to 53, Animals remaining with their 

 mothers as yearlings and 2-year-olds grow 

 and develop more rapidly than those that 

 are cast off as yearlings. A number of 

 marked bears have exhibited airline move- 

 ments exceeding 50 miles, and at least 7 

 bears marked within Yellowstone National 

 Park have been killed by hunters outside 

 the Park. 



14 



