Chapters 1 - U.S. Fish and Wildlife Service

Refuge Resources
with the intent of breeding and raising their young. The most important of these is the Federally
endangered California least tern, which nests annually on NASA Island. Other summer residents
that have nested on the Refuge include the black skimmer, western kingbird, western bluebird,
and hooded oriole. In addition to nesting summer residents, the Refuge also provides late summer
habitat for post-breeding species such as California brown pelican and elegant tern. Most postbreeding
species stay for only a few weeks before moving on to their winter foraging areas (CDFG
& USFWS 1976).
Year-Round Residents
Year-round residents of the Refuge include water-dependent birds, as well as birds typically
associated with upland areas. Some of these birds breed on the Refuge, while others forage on the
Refuge, but breed in nearby areas. Still others are migratory birds represented year-round in the
marsh by nonbreeding, summering individuals (e.g., willet, black-bellied plover, long-billed curlew,
marbled godwit). Gadwall and mallard are two species of migratory ducks that are represented
year-round by those individuals that choose to nest and raise their young on the Refuge. The
Federally endangered light-footed clapper rail and State endangered Belding’s savannah sparrow
are two the Refuge’s most important year-round residents. Both spend their entire lives within the
coastal salt marsh habitat, with the rail favoring cordgrass-dominated salt marsh areas and the
sparrow generally utilizing the pickleweed-dominated salt marsh habitat.
Other species that can be observed year-round and regularly or occasionally nest on the Refuge
include great blue heron, red-tailed hawk, American kestrel, killdeer, black-necked stilt, American
avocet, northern mockingbird, loggerhead shrike, and song sparrow.
4.3.4.2 Mammals
A comprehensive mammal survey has not been conducted for the Refuge; therefore, information
about the mammalian populations on the Refuge must be derived from data obtained during
monthly night mammal surveys conducted throughout NWSSB and observations made during
general Refuge management activities and monthly bird surveys. Nineteen species of mammals
were listed as present or potentially present on NWSSB, including Refuge lands, in 1990. Since
then, the red fox ((Vulpes vulpes regalis or macroura), a native of North America but not of
southern California, is believed to have been extirpated from the site. In addition, no evidence of
badger or gray fox activity has been observed in the area for many years, although both species
historically occurred on the site. Based on this information and the limited amount of upland
habitat located within the Refuge boundary, it is likely that fewer than 17 species of mammals are
currently present on the Refuge. This includes two potential bat species, Brazilian free-tailed bat
(Tadarida brasiliensis) and big brown bat (Eptesicus fiscus) (USFWS and U.S. Navy 1990),
however, no survey data for bats are available to verify the presence or absence of specific bat
species. Finally, this figure does not include feral cats, which may be present on the Refuge from
time to time.
Some of the species known to be present on the Refuge include: San Diego black-tailed jackrabbit
(Lepus californicus bennettii), a California Species of Concern, California ground squirrel
(Spermophilus beecheyi), and coyote (Canis latrans). The burrowing habits of the ground squirrel
have contributed to erosion problems along the artificial slopes of the Refuge’s restored ponds,
particularly Forrestal Pond and Case Road Pond. Coyote, which generally prey on smaller
mammals such as mice, squirrels, and rabbits, also pose a threat to the light-footed clapper rail and
California least tern because of their appetite for chicks and eggs.
Draft Comprehensive Conservation Plan/Environmental Assessment 4-49