thus reduces both survival of the younger animals and vigour in the older. To 

 study the effects of snow cover on survival and distribution of deer, we have 

 maintained a network of snow stations throughout the deer range since 1953. 

 Using a tentative index of severity, we have been able to predict hunting success 

 from the previous winter's snow records on several occasions. This information 

 has been put to good use by the Fish and Wildlife Branch. In future, snow studies 

 will be gradually incorporated into a general investigation of limiting factors along 

 the northern fringe of the range. 



The second major problem concerns the declining productivity of much of the 

 Ontario range. To thrive, deer need an abundant supply of palatable shrubs and 

 coniferous cover for shelter in winter. The major pine logging activity of 1850- 

 1910 resulted in residual stands that favoured deer until recently. Now, however, 

 much of the forest cover east of Lake Superior has become too mature to provide 

 good food for deer. Also, through selective removal of conifers (which have 

 always been more marketable), good winter shelter for deer has become too scarce 

 to support needs large enough to satisfy the increasing hunter demand. Since it is 

 evident that the state of the forest is the most important single factor governing 

 the welfare of our deer herds, it follows that manipulation of the forest environ- 

 ment could be our most effective management procedure. In order to learn to 

 manage our forests so as to create better deer habitat without reducing timber 

 production, the Big Game Unit is co-operating with the Forestry Section of the 

 Research Branch, the Timber Branch, and the Tweed Forest District staff in a 

 study of experimental manipulation of lowland conifers in deer yards in South 

 Canonto Township. 



Research on moose was concerned with a study of the reproductive rate in 

 a heavily hunted population along the Red Lake road. A sufficient number of 

 jaws and reproductive tracts, to determine ages and productivity, were collected 

 for analysis during the coming year. In co-operation with the Silviculture Section 

 of the Timber Branch and the staff of the Sioux Lookout Forest District, an 

 attempt was made to assess a method of aerial photography for censusing moose. 

 A known number of horses working in a pulo cutting operation were photographed 

 at 2,400, 1,800 and 1,200 feet altitude. The results were inconclusive. It was 

 apparent, however, that photographic surveys of moose populations would be 

 much more expensive than the present method of visual maoping. 



In co-operation with the staffs of northern Forest Districts, assessment 

 of the numbers and distribution of woodland caribou were completed for the most 

 important winter range. Surveys of over 107,000 square miles during January, 

 February and March showed herds of varying sizes in a discontinuous distribution. 

 Density averaged one per 3.5 square miles in some of the best winter range to one 

 per 94.5 square miles in range which had been partially destroyed by fires. 



Studies of reproductive success and mortality factors were continued. 



Upland Game and Waterfowl 



The re-organization of this unit was completed. A biologist has initiated 

 research programs on several species of grouse, which are directed toward improved 

 hunting for Upland Game. A project is now in progress to assess the characteristics 

 of pinnated and sharp-tailed grouse and their hybrids which have occurred 

 naturally on Manitoulin Island. It may be possible to extend the distribution of 

 these grouse into other areas of Ontario which are not supporting grouse or 

 pheasant populations at the present time. 



Aerial surveys of Canada Goose production in the Hudson Bay Lowlands, 



267 



