found on the dunes (Nagano 1982; Mclntire 

 1985). Both species lay their eggs in the 

 sand, and the larvae construct vertical 

 burrows approximately the same diameter as 

 the head, from which they trap food in a 

 manner similar to that described in Section 

 3.4. These beetles are found in only two or 

 three other localities in southern California. 

 Another beetle, Notoxus monodon, feeds on 

 detritus beneath dune vegetation (Figure 

 3.27). This species has glossy white hairs on 

 its body, presumably to protect it from the 

 sun. The larvae inhabit burrows beneath dune 

 plants (Mclntire, pers. comm.). 



It is evident from the above discussion that 

 the insects of the dunes are closely associated 

 with the dune vegetation, particularly native 

 species. In contrast, the birds that use the 

 dunes prefer the open sand areas. Two rare 

 species nest on the dunes of Tijuana Estuary 

 (Figure 3.28), and a variety of other species 

 feed on the sandy shores adjacent to the dunes. 

 The dunes also provide a refuge for shorebirds 

 when high tides inundate their feeding areas. 



Espinoza (in Entrix et al. 1991) found 

 three species of lizard using the dunes. The 

 San Diego coast horned lizard (Phrynosoma 

 coronatum blainvillei) was found on the 

 southern dunes. It feeds almost exclusively on 

 wood or harvest ants. The silvery legless 

 lizard (Anniella pulchra pulchra) occurred in 

 the same area and was associated with debris 



and low vegetation, which protects it from 

 desiccation. The side-blotched lizard (Uta 

 stansburiana) was very abundant on the 

 reconstructed dunes. 



The Federally endangered California least 

 tern (Figure 3.28) nests in depressions in 

 the sand along the dunes. Their eggs and 

 chicks are vulnerable to a number of 

 terrestrial and avian predators, as well as 

 accidental or intentional disturbances by 

 humans. If the first clutch fails, adult least 

 terns may attempt to nest again. The least 

 tern is a colonial nesting species that prefers 

 sandy dunes with low amounts of dune 

 vegetation and debris (less than 3%; Minsky 

 et al. 1983). Females lay an average of two 

 eggs in a small depression or scrape in the 

 substrate. Young are fed exclusively on fish 

 by both parents. Young least terns fledge at 3 

 weeks, and they gradually learn to feed on 

 their own in inland lakes and estuaries. 



Also nesting on the dunes is the relatively 

 rare snowy plover (Figure 3.28). This bird 

 is not a colonial nester but often associates 

 with colonies of California least terns (White, 

 pers. comm.). Snowy plovers lay an average 

 of three eggs. Chicks leave the nest within 24 

 hours of hatching and immediately follow the 

 parents to foraging areas along the sandy 

 shoreline and mudflats. Snowy plovers feed 

 mainly upon invertebrates along the water's 

 edge on the sandy shoreline. 



Figure 3.28. Birds that nest on the sand dunes are the California least tern and the snowy plover. 

 Mclntire collection, © 1986 by Zedler. 



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