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ABSTRACT The southern range limit of the invasive Asian shore crab,Hemigrapsus sanguineus,along the United States East coast is further north than expected based on its native distribution. We investigated potential factors that may limit the southward spread of this species along the Mid‐Atlantic and South Atlantic bights from Virginia to South Carolina, including metabolic constraints, food availability, and habitat limitation. We searched sites identified as potential habitat forH. sanguineusto verify the presence/absence of the crab, measured the metabolic rates of crabs at their current southern range edge for comparison with previous measurements made further north on the New Hampshire coast, used digital images captured at each site to determine whether the availability of potential food decreases south of the current range limit, and used Google Earth to measure distances between suitable habitat patches north and south of the current range limit to determine whether habitat availability limits the range expansion toward the south. We encountered the species ~64 km further south than the documented range limit at Oregon Inlet, North Carolina. We found no difference in metabolism between crabs at the southern range edge compared to crabs from New Hampshire, and no consistent difference in the abundance of available food between sites north and south of the current range limit. However, we found greater distances between suitable hard‐substrate sites south of the current range limit than between sites found within the current range. We suggest that the availability of suitable habitat is the primary driver limiting the further southward range expansion ofH. sanguineus.
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Muskrat Island: Behavioral Shifts of an Insular Muskrat ( Ondatra zibethicus ) Population in the Gulf of Maine
ABSTRACT The aftermath of the North American fur trade resulted in the depletion of many furbearing mammal populations in their native North American range while simultaneously creating invasive populations of these species through translocations worldwide. Here, we document the ongoing results of this mass ecological experiment by describing the natural history of a remnant fur colony of muskrats (Ondatra zibethicus) putatively introduced to the Isles of Shoals archipelago in the Gulf of Maine in the early 20th century. Through a combination of intensive surveys and camera trapping, we document how muskrats have been influenced by insular conditions under expectations of island biogeographic theory. Unlike other translocated muskrats that have produced successful wetland‐restricted populations in continental Europe and Asia, the Shoals muskrats appear to have shifted their habitat use and lodge building behavior and have encountered a new predator: gulls (Laridae). This Nature Note formalizes decades of anecdotal observations and provides important insight into the ecological flexibility of muskrats given the paradox of a species that is apparently now declining in its native range but expanding outside of it.
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- Award ID(s):
- 2109168
- PAR ID:
- 10596101
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Ecology and Evolution
- Volume:
- 15
- Issue:
- 6
- ISSN:
- 2045-7758
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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