Hooks Island

As is common on large areas of ground, grass grows on Hooks Island. Specifically, several species of cord grass provide a habitat for various animals. In 1997, a study discovered that the native cord grass, Spartina foliosa, was being displaced on Hooks Island by the invasive species Spartina alterniflora, which "grows denser than the native species and makes it harder for animals to move around".[7]

The S. alterniflora, originally introduced to the area in 1973 by an Army Corps of Engineers project to control erosion and restore marshes in the Bay, hybridized with native cord grasses, forming dense growth aboveground and a dense root system, which displaced both surface dwellers and animals that lived beneath the mud.[8]

When the 1973 attempt to reverse damage to the marshes was eventually found to be harmful for wildlife, it was itself reversed—the California Coastal Conservancy's San Francisco Estuary Invasive Spartina Project was able, with the aid of the herbicide imazapyr as well as physical removal methods, to heavily reduce the overall footprint of S. alterniflora growth across a 70,000-acre "work area", from 805 acres in 2005 to 28 acres in 2016 (at which point $30 million had been spent).[8]

While this project was a "resounding success", federal officials required the conservancy to reverse part of their reversal of the initial reversal, after it was found that the (then-endangered) California clapper rail had taken up residence in thickets of the invasive species.[9][8]

Numerous birds have been known to live on Hooks Island, such as the near-threatened[10] California clapper rail. In 2011, a Point Reyes Bird Observatory Conservation Science report found that approximately 14 clapper rails had been found in the Baylands, and 19 clapper rails were "known to exist" at Palo Alto Harbor and Hooks Island.[11] Other estimates of the total Baylands population in 2011 included "approximately 15–29 individuals".[2] However, in 2010, there had been as many as 22 clapper rails.[11] In 2013, allegations were made that feral cats were living on Hooks Island and killing them.[11] While it is broadly accepted that there are many cats in the San Francisco Bay area,[12] the extent of their presence in the Palo Alto Baylands (and of their role in the killing of clapper rails) was disputed. While the city's division manager of open space, parks and golf claimed to have "personally seen feral cats hunt and catch birds in the Baylands Nature Preserve", a volunteer at the Palo Alto Humane Society offered a rejoinder to this claim, stating that "compared to people, the damage feral cats do is minor".[11]

• 
  The salt marsh harvest mouse can survive only in the vegetation of salt marshes.
• 
  The clapper rail majestic.

• List of California Department of Fish and Game protected areas
• List of islands of San Francisco Bay
• Salt marsh harvest mouse