also available from trapping and hunter-killed samples, we 

 considered the modeled estimates more accurate than those 

 derived from small samples of trapped and hunter-killed deer. 

 Given those small samples, randomness, hunter selection, and 

 misaging could significantly influence proportions assigned to 

 each age class. The general form and structure of the 2 

 estimates was similar, though age-specific differences appear 

 (Fig. 4.10). Both generally detected cohorts with poor 

 survival (1971, 1975, 1983, and 1984). 



The general age structure of the population was the same 

 during 2 different periods of population increase, 1968-1971 

 and 1979-1983 (Fig. 4.9). Age structure was also similar for 

 2 periods of decline, 1972-1974 and 1984-1986. The major 

 difference was that the population decline during 1972-1974 

 was more severe and population size was lower than during 

 1984-1986. Continued low fawn recruitment during 1975-1977 

 further reduced population size and perpetuated the small base 

 in female age structure during the earlier decline. 



It is apparent from age structural estimates (Fig. 4.9 

 and Table 4.4) that age structure alone is not a useful 

 criterion for predicting future population trends. Rather, it 

 was most useful for determining or verifying what had happened 

 in the past. Used alone, or with invalid assumptions, age 

 structural data may be potentially misleading in determining 

 population trend. Population declines during both 1971-72 and 

 1983-84 were preceded by several years in which the pyramidal 

 age structure represented the classic, "healthy and growing" 

 population. Both declines were represented by sharp, rather 

 than gradual deviations from this age structure. 



A stable age structure cannot be expected for this 

 population. Persistence of a "normal" or "stable" age 

 structure requires relatively constant natality and mortality. 

 On our study area, natality and mortality of fawns occurred as 

 periods of several years of both boom and bust. Hunting 

 mortality was variable. Although natural mortality of adults 

 appeared relatively stable during most years, it occasionally 

 occurred as a pulse of catastrophic mortality. The greatest 

 age structural stability occurred from spring 1975 through 

 spring 1978 (Fig. 4.9), when fawn survival was low, but 

 relatively stable, and adult female mortality was low and 

 stable. 



Only 16.5% of 466 adult females aged during 1960-1985 

 were 7 years or older; 40% were yearlings or 2-years-old. The 

 maximum age recorded for females was 16 1/2 years. 



98 



