Cox Island, Siuslaw Forest
Cox Island, Oregon Cox Island, Siuslaw Forest © Roy Lowe

Places We Protect


Cox Island Preserve

An island saltmarsh on Oregon's central coast supports eel grass, egret and muskrat.

Why You Should Visit    

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


187 acres

What the Conservancy Has Done/Is Doing

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 working to control the species and prevent it from spreading to other coastal marshlands.


What to See: Plants

The preserve supports several important habitats including eel grass (Zostera marina) beds in the lower estuary and Henderson’s checkermallow (Sidalcea hendersonii).

What to See: Animals

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:

  • Stay out of the old house on the property as it is no longer structurally sound.
  • No dogs. Preserves harbor ground-nesting birds and other wildlife that are extremely sensitive to disturbance.
  • No bicycles or motorized vehicles. Native plants and research sites are easily trampled.
  • No hunting, camping or campfires.
  • For groups of 10 or more, please contact us before visiting a preserve (a volunteer naturalist guide may be available).
  • Please bring a bag and carry out any trash you find.
  • Please report to us any problems you observe (e.g., camping, plant removal, hunting, off-road vehicle damage, etc).