SPECIAL TECHNIQUES 



101 



By the new method the volume of all food items in the specimens examined is added 

 together and then the actual percentage of each is computed. It is as though all the items 

 from all the birds were dumped together and then each kind of food separated and the per- 

 centage of its volume in relation to the whole computed. On this basis, the four beechnuts 

 now equal but 18.18 per cent of the total volume eaten by the two birds. By using this system, 

 a given amount of a single item has the same relationship in all instances. 



As will be seen by the accompanying table, the differences tend to cancel out where large 

 numbers of examinations are involved. But even with 1,093 grouse analyses, the differences 

 with some food species, figured by both methods were substantial. On the basis of use, four 

 of the species classed among the first 1.5 by the old method were replaced under the new 

 method of computation. Lastly, the "volume" method is quite as easy as the old one. 



TABLE 98. COMPARISON OF THE "AVERAGING PERCENTAGES" AND "AVERAGING 

 VOLUME" METHODS OF SUMMARIZING GROUSE FOODS 



Fowls 



Aspen 



Cherry 



Birch 



Hdspberry 



Hui>-hurnbeani 



Thortmpple 



.Struwberry 



\pple 



Beech 



.Sumach 



"Based on 1.093 birds. 

 .^Based un :I0R birds. 



All seasons* 



Averaffe by 

 volumes 



Per cent 



12.4 

 10.6 

 9.2 

 8.8 

 .1.7 

 4.S 

 .3.8 

 .1.8 

 .1.0 

 2.S 



Average by 

 percentages 



Per cent 



10.3 

 10.4 

 7.0 

 8.8 

 4.2 

 6.1 

 3.8 



4i5 

 3.3 



FallA 



Average by 

 volumes 



Per cent 



6.6 

 7.4 

 1.2 

 6.0 

 11.8 

 3.5 

 6.9 

 8.8 

 3.3 



Average by 

 percentages 



Per cent 



1.8 

 6.4 

 3.3 

 2.3 

 3.9 



15.9 

 1.7 

 4.6 



10.3 

 3.1 



It was not always practical, however, to take advantage of the greater accuracy permitted 

 by the use of volumes. For example, the amount of food eaten by a 3-week-old chick is many 

 times greater than the capacity of a chick less than a week in age. Obviously, one must expect 

 an increase in capacity as the bird matures. Since it is impractical to collect, each day, 

 sufficient specimens representative of each successive stage of growth, it becomes necessary to 

 consider larger groupings witli the less desirable, but none the less unavoidable, difference 

 in capacity. For this reason the discussion of the juvenile diet is based upon averaged 

 percentages, otherwise the quantity of food eaten the last half of June would so far outweigh 

 that of the first half as to cause the former to lose all significance. 



Determining Weather Rel.'VTIonships 



It has been contended in the literature that adverse weather has been related to some periods 

 of grouse scarcity that have occurred. The weather, however, was not described in other than 

 general terms, such as long hard winters or cold wet springs. Tlie task of specifically relat- 

 ing the various weather constituents to ruffed grouse was therefore attempted along two lines. 



One series of problems was attacked with data from daily records of temperature, wind, 

 humidity and precipitation ( snow and rain ) taken at the Ithaca station of the U. S. Weather 

 Bureau, 15 miles from the study area at Connecticut Hill. Supplemental information was 

 also secured from readings taken from time to time on the area itself. The minor uncon- 



