REGULATION OF THE GROUSE HARVEST 675 



may be teeming with birds, another at or near a low point. All these characteristics com- 

 bine to make a census notably difficult. 



Yet the picture is not all dark, otherwise the Investigation could have learned little of the 

 characteristics of grouse populations. The birds are sedentary' in that the adults seem to 

 establish certain territories. When caught near the edge of these they tend to turn back. 

 The fact that individuals or groups of birds are usually scattered makes it easier to avoid 

 duplication once the extent of their territories has been learned. Furthermore the males 

 establish drumming logs which they use regularly in the spring. Likewise, the females nest 

 for the most part in predictable portions of their habitat though their numbers cannot be 

 counted at this time by such an index as the docker droppings (enlarged droppings from 

 nesting birds) of the red grouse of Scotland which commonly leaves them at the same place 

 each day along watercourses. 



Determining Grouse Populations 



Reports of interested observers, game protectors and other field workers have commonly 

 formed the basis of abundance estimates preceding the fall hunting season. If ruffed grouse 

 were as predictable in their increase as Scotch grouse we, like the British, might rather 

 estimate the fall crop from the number of breeding birds in the spring. But there are more 

 accurate ways of arriving at such an inventory, although none of the grouse census methods 

 so far developed is without serious drawbacks. 



The birds are generally too widespread to make practical the expensive direct count prac- 

 tice* used by the Investigation on its study areas. True, such complete censuses are quite 

 workable for small areas providing funds, trained man])owcr and direction are available. On 

 large tracts the time required, as well as the costs, is prohibitive. 



The next most accurate procedure is to establish a series of sample plots in representative 

 grouse habitats to be measured yearly by the complete census method. This presupposes that 

 the coverts selected have been surveyed in advance and are normally found to carry large 

 numbers of birds. The difficulty here lies in the number of such sample plots which must be 

 covered to give a balanced picture. On a 5,000-acre area, for instance, at least a dozen would 

 probably be necessary. This would make the number prohibitive if a county or a state were 

 involved. 



Because only highly productive areas are chosen, this method will yield a figure far in excess 

 of the actual population. Used as an indicator of abundance trends, however, it is appar- 

 ently fairly reliable. 



King"'* developed a somewhat different application of the sample plot method for Minne- 

 sota conditions bv dividing the area to be censused into 40-acre blocks the boundaries of 

 which are followed in making the survey. Figuring the average grouse flushing distance from 

 those recorded each day the proportion of the total area covered is computed by multiplying 

 twice this distance by the length of line covered each time the survey is carried out. The 

 amount of each type of cover over the entire area is established by a type survey. The strips 

 are "walked" at intervals and a record kept of the number of grouse flushed within each 

 type. By comparing the number of birds flushed per unit of each type within the strips to 

 the total of each on the area, an estimate of the total birds to be found in each type may 

 be secured. These added together give an estimate of total area population. 



* See Appendix, p. 699. 



