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Psyche 
[Vol. 95 
Table 1. Nicrophorus spp. captured on Block Island 
Dates 
Na 
No 
Nm 
Nt 
5/26-5/30 
2 
16 
10 
0 
6/9-6/12 
15(2) 
20 
0 
0 
6/24-6/28 
43(5) 
68 
14 
2 
7/14-7/18 
80(8) 
35 
8 
17 
7/28-8/1 
26(4) 
34 
24 
13 
Na = TV. americanus, No = TV. orbicollis 
Nm = TV. marginatus, Nt = TV. tomentosus 
The numbers in parentheses indicate the number of total captures which had 
previously been captured and marked. Recapture information is available only for 
TV. americanus. 
original capture and 15 of 19 recaptures were made in the same 
location where the individual was originally marked. The popula- 
tion estimate was based on 19 recapture events in five sampling 
intervals and yielded a mean estimated total population size of 391 .4 
individuals. The 95% confidence intervals for the estimated mean 
were 258, 600. 
N. americanus showed no significant preference for avian or 
mammalian carcasses (G = 1.061 < x 2 . 05 ( 2 ) = 5.99). In our experi- 
mental choice situation, the male and female did not always cooper- 
ate in burial. The mammalian carcass was chosen by 44% of the 
individuals and the avian carcass was chosen by 25% (N = 16). In 
the laboratory, N. americanus buried both avian and mammalian 
carcasses and successfully reared broods on both types of carrion. 
In three trials, N. americanus outcompeted N. orbicollis for prey. 
In one trial, the male and female N. americanus buried the carcass 
together, and in the other two the male buried the carcass alone 
while the female remained in the enclosure but was not found with 
the male in the burial chamber. These results are not surprising, as 
in Nicrophorus species, size has been shown to be the single most 
important determinant of success in interspecific competition (Wil- 
son and Fudge 1984; personal observation) and there is almost no 
overlap in size between N. americanus and N. orbicollis. 
In the field, of 44 carcasses provided for burial, nine were buried 
by N. americanus (20%), four by N. orbicollis (9%) and three by N. 
marginatus (7%). The remaining carcasses were not buried. N. orbi- 
collis primarily buried carcasses ranging from 20-25 grams on Block 
