Fawn Production, Mortality, and Recruitment 



General Patterns in the Population 



1975-1986 



Fetal rate for 38 pregnant females collected in spring 

 1958, 1963, 1984, and 1985 was 1.55 fetuses : female. We 

 consider that rate to be below average because 64% of the 

 sample was from 1984 and 1985, the lowest years of production 

 on record. 



Initial production of fawns was also recorded each year 

 during 1976 - 1986 as fawn-at-heel ratios during June (Table 

 5.1). Those data did not account for females that were not 

 pregnant. They also underestimated initial litter size to 

 some degree because fawn mortality was ongoing at the time the 

 data were collected. Additionally, during 4 of 11 years, a 

 radio-collared fawn originally classified as a single, was 

 later determined to be a twin. Undoubtedly, some non-radio- 

 collared litters included in the sample may have also had an 

 additional fawn. That likelihood was verified by comparing 

 litter size during 1976-1983 between the population as a whole 

 and radio-collared females that were reobserved often. Single 

 fawns comprised 43.8%, twins 54.8%, and triplets 1.4% of 292 

 litters recorded in initial fawn-at-heel surveys (Table 5.1). 

 Singles were 31.6%, twins 65.6%, and triplets 2.8% of 177 

 litters for radio-collared females. Most of this difference 

 occurred because reobservations of radio-collared females 

 detected a larger litter size than recorded for the initial 

 observation. 



The mean litter size for aggregate data during 1976-1986 

 was 1.58 fawns per productive female. The highest was 1.76 

 and the lowest was 1.25 fawns per productive female in 1979 

 and 1985, respectively. The lowest ratio was 71% of the 

 highest, indicating the range in adjustment of litter size 

 under the extremes in conditions experienced during this 

 period. 



During 1979, the year of best production, 73% of litters 

 contained more than 1 fawn. A minimum of 11 sets of triplets 

 were known to have been born, 7 of which survived through 

 December. These 11 sets of triplets represented 3.6% of 

 litters for breeding age females on the study area. The fawn- 

 at-heel ratio recorded in mid-June 1979 (Table 5.1) also may 

 have been lower than the actual ratio at birth. 



Fawn-at-heel ratios were multiplied by the percentage of 

 the female population estimated to be productive (see 

 footnotes, Table 5.1) to obtain an estimate of the fawn: female 

 ratio for the population during mid- June. Those ratios were 



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