The Ecology of Tijuana Estuary, California: An Estuarine Profile

Figure 48. Birds that nest on the sand dunes are the California least tern and the snowy plover. Mclntire collection,
copyright 1988 by Zedler.
Table 15. California least tern nesting data, 1982- abundant species on his beach site. The beach
1985 (from Least Tern Recovery Team, unpubl.). was most heavily used during July-August and
least during December-January.
Tijuana Estuary
Cal~fornia
-.__l-__.ll- -- I__-_ _
Year Nest~ng Pairs Fledglings Nest~ng Pars
Belding's Savannah sparrows often forage on
the dunes, especially when an abundance of kelp
has washed ashore. The decaying kelp harbors
large numbers of insects, especially flies. At
Tijuana Estuary, several sparrows nest in small
patches of pickleweed and saltgrass that are
1982 21 -30 17 1015-1245
1983 60-65 50+ 1196-1321
1984 66 1 2-20 931 -1 002
1985 32 1 8-20 1100-1112 surrounded by dunes and dune vegetation (White,
pers. comm.).
The dunes and beach habitats are dynam~c, and
recent storm damage has altered the native
communities. In order to open the estuary to tidal
Boland (1981) found that six species of flushing, the sand that had blown and washed into
shorebirds were abundant in his beach study site. the estuarine channels was dredged and replaced
These included sanderling, willet, marbled godwit, on the dunes in December 1984. A revegetation
whimbrei, snowy plover, and black-bellied plover. program designed to stabilize the dunes and
Additional species that were not present on his prevent recurrence of mouth closure has been
beach site but are commonly observed feeding in initiated (Jorgensen, pers. comm.; B. Fink, SDSU, in
the intertidal beach areas include the least prog.). This program will examine the response of
sandpiper, western sandpiper, and dowitcher. three native species, primrose, sand verbena, and
Boland characterized the partitioning of beach dune ragweed, transplanted to the foredune, dune
habitats on the basis of the depth of sediment that ridge, and backdune A complementary study on
the prey organisms occupy and the depth of water ~nteractions between native (sand verbena) and
in which the birds would forage. The results non-native (sea rocket, Cak~le maritrma) species is
(Figure 49) describe feeding strategies of the six also in progress (Wood, in prog.)