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Kozol, Scott, & Traniello — Nicrophorus 
175 
beetles. Because TV. americanus are the largest carrion beetles in 
North America and even the smallest TV. americanus overlap in size 
only slightly with the largest TV. orbicollis and TV. marginatus, it 
seems unlikely that TV. americanus have been outcompeted by other 
Nicrophorus species. However, factors other than size that might 
affect the outcome of competition (such as temperature or patterns 
of activity [Wilson et al. 1984]) remain to be examined. 
The decline of N. americanus then may be more likely related to 
the impact of human activity. The widespread use of pesticides has 
been cited as a potential factor in the decline of non-pest insect 
populations but there have been few documented losses caused by 
pesticide use (Pyle et al. 1981, New 1984). This hypothesis initially 
appears attractive to explain the survivorship of N. americanus on 
Block Island because the island was never sprayed heavily with 
broad spectrum insecticides such as DDT. However the evidence 
against this hypothesis includes the following. TV. americanus has 
disappeared from numerous other areas where DDT was never 
sprayed. TV. americanus was collected in the 1960’s from areas which 
had been sprayed heavily with DDT and lastly, congeners such as TV. 
orbicollis and TV. marginatus, who have a very similar reproductive 
biology, have apparently suffered no decline in population size. 
The habitat(s) occupied by TV. americanus before its decline was 
not clearly described so it is very difficult to ascertain how severe an 
impact the loss of habitat has had on this species. However, the 
increasing use of land for urbanization and commercial agriculture 
and forestry has had a demonstrated negative impact on numerous 
insect species (Pyle et al. 1981). This hypothesis, though tentative, 
appears to be the most plausible. Although there is no data from 
this research thus far to draw any significant conclusions about 
causal factors in the decline of TV. americanus it is recommended 
that the search for answers to these questions focus on factors 
related to changes in, or loss of suitable habitat, that have made it 
impossible for TV. americanus to survive today in areas where it was 
once successful. 
Acknowledgments 
This study was supported by grants from the Nature Conservancy 
and the Massachusetts Natural Heritage Program. We would like to 
thank Keith Lewis, Larry Master, Dale Schweitzer, Nancy Breaker, 
Peter Dunwiddie, and Sam Beshers. 
