In examining possible effects of nutrition on the 

 reproductive period of deer on our study area, we assumed that 

 birth date was most likely to vary with nutritional plane of 

 the female. Birth dates of fawns captured during 1977-1987 

 were estimated from the equations of Robinette et al . (197 3) 

 unless known to have been the day of capture. Data for 1976 

 were excluded because capture operations started later than in 

 all other years. Capture dates during 1977-1987 ranged from 

 12 June to 28 June and averaged 16 June. Only fawns estimated 

 to have been born by 14 June each year were used for 1 

 comparison, while all fawns captured were used for another. 

 Although fawns born only during the early portion of 

 parturition were included, the means and ranges in birth dates 

 should indicate relative differences among years. 



Mean birth dates (Fig. 5.1) represent conditions 

 prevailing from summer prior to conception through late winter 

 before birth. Thus, conclusions drawn about birth weight 

 during a particular year apply to nutritional conditions 

 during the year prior to birth. If early birth dates were 

 related to superior female condition, nutritional conditions 

 prevailing from summer 1978 through spring 1979 and from 

 summer 1986 through spring 1987 must have been far above 

 average, verifying other data (Chapter 4). The first period 

 coincided with very low deer density, the second with very 

 high deer density. The worst nutritional conditions must have 

 occurred from summer 1983 though winter 1984. Conditions 

 during summer 1981 through spring 1982 and summer 1976 through 

 spring 1977 may also have been poorer than average. 



Although average birth dates indicated that nutritional 

 conditions were near average during 1984-1985, that 

 interpretation must be tempered by the information on low 

 pregnancy rates of females during those years . Because about 

 20% and 17% of 2-year-old and older females were either not 

 carrying viable fetuses or had late births in 1984 and 1985, 

 nutritional conditions probably were poorer than indicated by 

 average birth date alone. Those females that gave birth to 

 viable fawns may have been in average condition, but when 

 balanced with the other females, the female population as a 

 whole was in poorer than average condition. 



Poor nutritional conditions may also have prevailed 

 during 1982-1983. Ten late-born fawns were observed during 

 the course of late summer and autumn fieldwork in 1983. The 

 highest number observed during any other year was 2 . 



Pregnancy, Ovulation, and Fertilization Rates 



Pregnancy rates were determined from females shot for 

 that purpose and from observations of marked females. Data 

 from 39 1-1/2-year-old and older females collected in the 



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