Seven miles inland from the Pacific Ocean, this island on Oregon's central coast is an excellent example of an estuarine saltmarsh ecosystem. Low elevation leads to daily floods at high tide. At low tide, the island is dissected by a maze of tidal channels, adjoined by expanses of mudflats.
East of Florence in the Siuslaw River
Volunteers help control the only known Oregon population of saltmeadow cordgrass (Spartina patens), an invasive, introduced species that threatens native wetland vegetation. Researchers believe it arrived decades ago in packing material for clams, and Conservancy ecologists and volunteers are testing methods of controlling the species to prevent it from spreading to other coastal marshlands.
The preserve supports several important habitats including eel grass (Zostera marina) beds in the lower estuary and Henderson’s checkermallow (Sidalcea hendersonii).
Abundant with softshell clams and shrimp, the nutrient-teeming mudflats provide feeding grounds for great blue herons from nearby rookeries. Over 80 species of birds and waterfowl, including great egrets, phalaropes, whimbrels and short-billed dowitchers are known to visit this largely undisturbed coastal marsh. Island residents include beaver, river otter, muskrat and mink. In addition, hawks and ospreys are commonly seen.
Due to extreme tidal fluctuations, special care is needed to ensure that boats are safely tied up and secured. Please visit the preserve during low tide only in the spring and summer. There are no official trails. Foot travel is difficult because small, but deep, tidal channels are often covered by vegetation.
Please observe the following guidelines while hiking:
Access to Cox Island is by boat. There is a boat ramp at the Siuslaw marina three miles east of Florence on Highway 126, near the small town of Cushman.
The island is one mile downstream from this point. The best places to land are on the northeast corner of the island, and near the old house on the north side.