478 



ARTIFICIAL PROPAGATION OF GROUSE 



TABLE 70. SUGGESTED CONDITIONS FOR THE INCUBATION OF GROUSE EGGS 



In connection with the above table there are certain qualifications to bear in mind. Because 

 of different rates of air movement in various makes of still-air type incubators the average 

 reading of temperature may vaj;y from 102°F. to 104°F. The references given above are for 

 a room temperature of 60°F. If the room temperature is low, for example 40°F., the incu- 

 bator temperature should read about V2°F- higher; and, if the room temperature is high, for 

 example 80°F., the incubator temperature should read about •!/2°F. lower throughout. This 

 is to compensate for the current of warmer air entering through the ventilators. 



The bulb of the thermometer normally is placed about two inches from the egg tray level. 

 The temperature should be higher when the bulb is more than two inches above the tray level 

 and it should be lower when the bulb is elevated less than two inches. 



Because it is important to secure the exact temperature, it often is desirable to take a read- 

 ing on clinical thermometers, the one placed on the floor of the egg tray, the other level with 

 the top of the egg. The optimum temperature for grouse egg incubation is 99V^°F. at a 

 point one-half to two-thirds above the bottom of the egg. It is a good practice thus to check 

 the incubating temperature at the beginning of each successive hatch for, as the season 

 advances, the temperature of the incubator room likewise usually increases. 



Unless one is skilled in still-air incubator operation, it perhaps is safest to open the venti- 

 lators a quarter during the first week, one-half the second week and three-quarters from the 

 15th to the 20th day. After that the ventilation should be reduced markedly. Such sugges- 

 tions of necessity are general and subject to modifications as experience directs. 



Whenever an increase in humidity is desirable, particularly at hatching time, all moisture 

 pans should be filled to allow as great an area as possible for evaporation. Otherwise, they 

 should be kept partially covered or left dry according to the humidity in the room and the 

 condition of the eggs as indicated by the last recorded per cent of weight loss or by the mois- 

 ture gauge. It is well to remember, too, that excessively evaporated or old eggs require a higher 

 humidity than do unevaporated or fresh eggs. 



Mcasuririf^ Inruhalion Proprcss. As proficiency is attained, a need is sensed for more def- 

 inite methods of determining the progress of the hatch. Two techniques are helpful — peri- 

 odic candling of the eggs in order to check on the progress of development and tlie checking 

 of weight losses to determiiK' the rate of evaporation of moislurc from the eggs. When one 

 becomes skillful in interpreting these indices, they will provide many a cue for modifications 

 of the suggestions heretofore mentioned. For instance, too rapid development of the embryo 

 itulicalps that the iiuubalor is being run at too high a temperature. This must be lowered 

 until the normal schedule of development is resumed, else dead germs and poor hatches are 



