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| The amount of energy consumed within an average city block is an order of
magnitude higher than that consumed in any other ecosystem over a similar
area. This is driven by human food inputs, but the consequence of these
resources for urban animal populations is poorly understood. We investigated
the role of human foods in ant diets across an urbanization gradient in Manhattan
using carbon and nitrogen stable isotopes. We found that some—but
not all—ant species living in Manhattan’s most urbanized habitats had d13C
signatures associated with processed human foods. In particular, pavement
ants (Tetramorium sp. E) had increased levels of d13C similar to d13C levels in
human fast foods. The magnitude of this effect was positively correlated
with urbanization. By contrast, we detected no differences in d15N, suggesting
Tetramorium feeds at the same trophic level despite shifting to human foods.
This pattern persisted across the broader ant community; species in traffic
islands used human resources more than park species. Our results demonstrate
that the degree urban ants exploit human resources changes across the city and
among species, and this variation could play a key role in community structure
and ecosystem processes where human and animal food webs intersect. | |
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