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Photo © Illinois Natural History Survey
Elephant Ear (Elliptio crassidens), listed as Endangered in Wisconsin, is found in large rivers in the western part of the state. Only very old relic individuals have been found since 1920. The only known host is the skipjack herring, which only very rarely occurs in the Upper Mississippi River and its tributaries.
The table below provides information about the protected status - both state and federal - and the rank (S and G Ranks) for Elephant Ear (Elliptio crassidens). See the Working List Key for more information about abbreviations. Counties shaded blue have documented occurrences for this species in the Wisconsin Natural Heritage Inventory database. The map is provided as a general reference of where occurrences of this species meet NHI data standards and is not meant as a comprehensive map of all observations.
Note: Species recently added to the NHI Working List may temporarily have blank occurrence maps.
| Summary Information | |
|---|---|
| State Status | END |
| Federal Status in Wisconsin | none |
| State Rank | S1 |
| Global Rank | G5 |
| Tracked by NHI | Y |
| WWAP | SGCN |
Note: a species guidance document is not available at this time. Information below was compiled from publication PUB-ER-085-99 (now out-of-print).
Identification: The black to brown shell is moderately compressed and elongated. Anterior end is rounded and the posterior end is obliquely truncated and sharp. The ventral margin is almost straight and the beak is slightly elevated. The nacre color ranges from salmon to purple. Length to 6 inches (15.2 cm).
Habitat: The black to brown shell is moderately compressed and elongated. Anterior end is rounded and the posterior end is obliquely truncated and sharp. The ventral margin is almost straight and the beak is slightly elevated. The nacre color ranges from salmon to purple. Length to 6 inches (15.2 cm).
State Distribution: Occurs in the Mississippi River and the St.Croix River.
Phenology: The only known host fish is the skipjack herring (Alosa chrysochloris). Breeding season is from April through July.
Management Guidelines: The primary host fish for this species, the skipjack herring, has nearly been eliminated in the upper Mississippi due to locks and dams restricting migration from the Gulf of Mexico. Habitat destruction and river pollution have resulted in mussel declines. Protection of habitat and improvements in water quality along with restriction of dredging, impoundments, sand and gravel mining, and navigational improvements would benefit this species. The development of fish runways to facilitate the movement of host species through or around locks and dams would help to protect the elephant ear. Without a suitable host fish, extirpation is inevitable in Wisconsin and other upper Mississippi states.
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Photo © Illinois Natural History Survey.
The table below lists the natural communities that are associated with Elephant Ear. Only natural communities for which Elephant Ear is "high" (score=3) or "moderate" (score=2) associated are shown. See the key to association scores for complete definitions. Please see the Wildlife Action Plan to learn how this information was developed.
| Natural community | Score |
|---|---|
| Warmwater rivers | 3 |
| Warmwater streams | 2 |
The table below lists the ecological landscape association scores for Elephant Ear. The scores correspond to the map (3=High, 2=Moderate, 1=Low, 0=None). For more information, please see the Wildlife Action Plan.
| Ecological landscape | score |
|---|---|
| Western Coulee and Ridges | 3 |
| Forest Transition | 2 |
| Western Prairie | 2 |
| Central Sand Hills | 1 |
| Central Sand Plains | 1 |
Ecological priorities are the combinations of natural communities and ecological landscapes that provide Wisconsin's best opportunities to conserve important habitats for a given Species of Greatest Conservation Need. The 10 highest scoring combinations are considered ecological priorities and are listed below. More than 10 combinations are listed if multiple combinations tied for 10th place. For more information, please see the Wildlife Action Plan.
* Ecological priority score is a relative measure that is not meant for comparison between species. This score does not consider socio-economical factors that may dictate protection and/or management priorities differently than those determined solely by ecological analysis. Further, a low ecological priority score does not imply that management or preservation should not occur on a site if there are important reasons for doing so locally.
Conservation actions respond to issues or threats, which adversely affect species of greatest conservation need (SGCN) or their habitats. Besides actions such as restoring wetlands or planting resilient tree species in northern communities, research, surveys and monitoring are also among conservation actions described in the WWAP because lack of information can threaten our ability to successfully preserve and care for natural resources.