246 



NORTH AMERICAN FAUNA 68 



so that 

 or 



i=0.31 (1) 



Now let Jo=number of juveniles in their first year after dependency let n= 

 number of years in juvenile stage 

 J = Jo+Jo(.915) +. . .Jo(.915)°-^ 



Also A=:Jo(.915)'^+Jo(.915)''*'+. • • 



~ 1-.915 ^"^^ 

 so that 



J 1-(.915)'^ 



■A=T9i5r- o^f^°^(2) 



1 



0.31= 

 1.31= 



(.915)'^ 



_1 



(.915)" 



or 



(.915)°=^!^ 



Whence n = 3 years approximately. This is the estimated length of the period 

 between the end of dependence and maturity for females. 



SUMMARY AND CONCLUSIONS 



1. It is indicated that breeding activity reaches a peak in fall, 

 but breeding activity was observed in all seasons. 



2. Unimplanted gestation is estimated to last for 7 to 8 months. 



3. Implanted gestation is estimated to last for 41/2 to 51/2 

 months. 



4. The total gestation period is estimated to last 12 to 13 

 months. 



5. The period between births, i.e., total length of the reproduc- 

 tive cycle, is about 2 years. 



6. The average annual birth rate among mature females is 

 50 percent. 



7. Parturition occurs in all months, but a minority of births 

 occur in fall and winter months. Parturition reaches a peak in 

 summer, and large fetuses occur with greatest frequency in 

 summer. 



8. Dependent young occur with greatest frequency in fall and 

 with least frequency in late winter and early spring. In fall, unim- 

 planted pregnancy reaches greatest frequency. 



9. Birth normally occurs on land. 



