Draft EA - San Diego International Airport

SAN DIEGO INTERNATIONAL AIRPORT – PROPOSED RUNWAY 9 DISPLACED THRESHOLD
of loss of habitat. 32
California horned larks have been eliminated as a nesting species at SDIA. Horned larks
are thought to nest at MCRD San Diego and are known to nest at Naval Air Station North Island. 33
Of the avian species discussed above, the California least tern, described in more detail below, has been
recorded to use the habitable areas of SDIA during the nesting season.
California Least Tern
California least terns breed from San Francisco Bay south to Baja California. In San Diego County, this species
is a fairly common summer resident from early April to the end of September. 34
Wintering areas are along the
Pacific coast of South America. This small migratory tern nests colonially on undisturbed, sparsely vegetated,
flat areas with loose, sandy substrate adjacent to open water foraging areas. The California least tern is
federally listed as endangered with loss of nesting habitat being the primary cause for the initial decline of the
population of the California subspecies. Few undisturbed beach nesting areas remain and California least
terns are now found in varied habitats ranging from mudflats to airports. Breeding California least terns begin
nesting in mid-May and June. California least terns abandon the nesting colonies by mid-August and migrate
south by mid-September. California least terns exhibit tenacity to the colony site where they first breed
successfully. Prey includes northern anchovy, top smelt, killifish, mosquito fish, shiner, surf perch, and mudflat
gobies.
California least terns have nested at multiple locations at SDIA with the first observations of terns thought to
be nesting at SDIA occurring in 1969. 35
It is likely, given the historic configuration of the San Diego shoreline
and the tern’s documented use of fill and airports, that nesting occurred at this site prior to 1969. 36
The site
was first monitored for tern nesting in 1970; and, in that year, SDIA supported the third largest colony in the
state. Nesting at the Airport has been documented in 28 of the last 36 years. Areas used for nesting by the
California least tern have been monitored annually by the CDFG since 1976. Figure 3-5 depicts California
least tern nesting locations on the Airport from 2003 through 2011. There is an annual fluctuation in the
number of least tern nests at SDIA; the cause of this fluctuation is not known. Table 3-3 lists the number of
least tern nests observed at SDIA from 2003 to 2012. It should be noted that some pairs of least terns may
have more than one nest.
32
33
34
35
36
Gallagher, S.R., Atlas of Breeding Birds, Orange County, California, 1997.
CH2M HILL, San Diego Unified Port District, Environmental Constraints Analysis for San Diego International Airport Master Plan 2020,
March 1999.
Unitt, P., San Diego Society of Natural History, The Birds of San Diego County, 1984.
Craig, A., Survey of California Least Tern Nesting Sites, California Department of Fish and Game Wildlife Management Branch, 1970.
Craig, A., Survey of California Least Tern Nesting Sites, California Department of Fish and Game Wildlife Management Branch, 1970.
Affected Environment
[3-26]
Draft EA