498 



ARTIFICIAL PROPAGATION OF GROUSE 



always clear, that strongly influence production one way or the other. Nor should it not be 

 forgotten that the results in terms of birds produced are usually better with small numbers 

 than with mass ])roduction. 



The picture at the Research Center was further complicated because it was necessary each 

 spring to use part of the available breeding stock for one oi; another of the several experi- 

 ments then underway. If uninterrupted attention could be given to the production of grouse 

 for liberation, it now seems possible to rear from two to five birds to eight weeks of age for 

 every female placed in the breeding pens. 



Production Equations 



For the reasons just indicated, it has not yet been possible to base a grouse production 

 schedule on the record established at the Center. Each season some progress has been made 

 experimentally in reducing the effect of the items which limit production. With such a stub- 

 born problem, however, 13 years are still insufficient to learn to recognize and control all of 

 the limiting factors. 



But those who would breed grouse artificially are naturally anxious to secure some basis 

 for determining a logical production schedule. For such, the best guide at present seems to be 

 the results obtained from experiments that have proved most successful after repeated trial. 

 Given the proper conditions and supervision, it would seem quite possible to equal or to exceed 

 the production indices here set up. 



TABLE 71. INDICES OF PRODUCTION 



Factors 



Number of adults in breeding stock 



Number of breeding; females 



Number of CKKs per female 



Total number of e^K^ 



I*ercenta(,'e of fertile ep^s —fertility 



Total number of fertile epjcs 



Percentatfe of fertile etr^rs Imtdiod — 



hat^^luibility 



Total number of eKj:s hat^lie<I 



PereetitaKe of chirk survival to 8 weeks 



(liberation aRe) — livnbility 



Total number chicks surviving to 8 weeks. 

 Number of youn^ birils held over for 



breediriK stock 



Percentage of full and winter survival 



Symbol 



A 

 I) 

 e 

 E 

 f 

 F 



h 

 II 



I 

 L 



C 



S 



Normal 

 range 



80-81% 



Best 

 record 



85 % 



Using these factors, which are based on results at the Research Center, estimated produc- 

 tion of chicks and of next season's breeders may be quickly figured or a check on progress to 

 date at any period during the season, may be obtained. The optimist will use the highest 

 figures, the pessimist the lowest, while the hopeful individual will, no doubt, take the averages 

 for each factor. Comi)iitations are in simple multiplications. For example: 



Number of females (B) x Number of eggs per female (e) = Total number of eggs (E). 

 Total number of eggs (E) x Per cent of fertility (f) = Number of fertile eggs (F). 

 Using the symbols, the equations are as follows: 

 E = Be 



F = B e f or F f 

 H = Befh uv Fh 

 L = B e f h 1 or HI 

 A (next season) - (A + C) S 



