is absent. Recent population dynamics are 

 presented in Section 3.9.2. 



Jorgensen (1975) suggested several 

 advantages of cordgrass-dominated marshes 

 for the rails. The tall grass provides cover 

 for protection against predators and the birds 

 weave a canopy of live stems over their nests 

 (Figure 3.12). Both the egg and brood nests 

 are woven of dead cordgrass stems. The nests 

 that are anchored to vertical cordgrass stems 

 can float, thereby preventing submergence; 

 the nests in cordgrass can be more firmly 

 anchored than elsewhere; the lower marsh 



areas are wetter and less accessible to 

 terrestrial predators, and the black-colored 

 chicks are camouflaged against the black 

 substrate of the lower marsh. Finally, their 

 most common foods occur in or near areas 

 where cordgrass is abundant. Yellow shore 

 crabs and lined shore crabs were the dominant 

 items in regurgitated pellets analyzed by 

 Jorgensen (1975). Further evidence of the 

 species' relationship with tidal cordgrass 

 marshes developed in 1984 when cordgrass 

 died and the Tijuana Estuary population of 

 rails dropped to zero (Chapter 5). 



Figure 3.12. The light-footed clapper rail finds cover, food, 

 and nesting material in the cordgrass marsh. Its nest is a 

 masterpiece of construction, with a floating platform and 

 protective arch, commonly made of cordgrass. Mclntire 

 collection, © 1986 by Zedler. 



38 



