CARCASS WEIGHT (g) 
172 
Psyche 
[Vol. 95 
TOTAL BROOD WEIGHT (g) 
Fig. I. Relationship of carcass weight to total brood weight. 
small and a reasonably narrow confidence interval was desired. 
However, it should be noted that N. americanus violates two 
assumptions common to virtually all population estimate analyses: 
1) that the population size remains constant for the duration of the 
experiment and 2) that all individuals are equally available for 
recapture. Because the estimate was made during a two month 
period, normal mortality and a pulsed recruitment of newly eclosed 
individuals could have resulted in fluctuations in the size of the 
population. In addition, at any one time, a proportion of N. ameri- 
canus in a given population will be unavailable for recapture as they 
will be underground rearing a brood. The latter factor can poten- 
tially yield an overestimate of mean abundance if the number of 
animals actually available for recapture in any one sampling interval 
is less than the total population because the number of total recap- 
tures may be underestimated. 
Maximum numbers of N. americanus were captured in pitfall 
traps in June and there was a decrease in pitfall captures in late July. 
This is a common pattern for Nicrophorus species (Anderson 1982a, 
