Figure 48. Belding's savannah sparrow 

 ( Passerculus sandwlchensis beldlngl ) . 

 Illustration by J. DeWald. 



Barbara Massey's long-term study of 

 this species' breeding habits and her 

 surveys of its distribution provide a 

 thorough description of its natural 

 history. Other investigators (e.g. 

 Poulson and Bartholomew 1962) have been 

 intrigued by the bird's physiological 

 mechanisms which allow it to live in 

 saline habitats. Its highly efficient 

 urinary system concentrates chlorides up 

 to five., times levels in the serum; thus 

 the bird can drink and process sea water, 

 even though it lacks nasal glands which 

 are the usual mechanism of salt excretion 

 in marine birds. 



Males of the species are easiest to 

 see because they set up breeding 

 territories in December or January and 

 maintain them until mid-August. 

 Territories are not necessarily large, 

 perhaps because they are not relied upon 

 for feeding, but mainly for attracting a 

 mate and protecting the nest. Feeding 

 often takes place away from the pickleweed 

 habitat, which may explain the birds' 

 ability to use non-tidal areas for 

 breeding. Boland (pers. comm. ; graduate 

 student, UCLA) has commonly observed the 

 sparrows taking insects along the sand 



dunes and intertidal flats at Tijuana 

 Estuary, and Massey (1979) has documented 

 feeding on insects in several habitats, 

 and Salicornia tips and Atriplex seeds 

 within the marsh. Massey's densest 

 breeding area, at Anaheim Bay (Table 16), 

 had 1^ territories within an area of about 

 1 acre, and the^smallest territory 

 measured about 250 m . 



Females build their first nests in 

 March, using Sal icornia twigs for the 

 shell and usually anchoring the nest above 

 the ground in dense vegetation. Two to 

 four eggs are laid, one per day. However, 

 if disturbed before the final egg is laid, 

 the female commonly deserts the nest. 

 Incubation seems to require about two 

 weeks. Chicks are fed by the adults for 

 another week or two, after which time the 

 pair may establish a second and possibly a 

 third brood. The latest date when parents 

 were seen feeding young was 12 August 

 (Massey 1979). This very long active 

 breeding season, coupled with the species' 

 sensitivity to disturbance, means that 

 human activities in the upper marsh must 

 be restricted for most of the year in 

 order to avoid further declines in 

 Belding's savannah sparrow populations. 



5.5 MAMMALS 



The study of salt marsh mammals in 

 southern California has not progressed 

 much beyond development of species lists. 

 Yet there are a number of very interesting 

 questions raised by the presence of mice, 

 rabbits, and other small mammals in an 

 intertidal habitat. For example, how many 

 rodents can tolerate the salt marsh 

 environment? How do they avoid drowning? 

 Can they use salt marsh plants as food? 

 Where do they obtain their drinking water? 



Some of these questions are answered 

 in Coulombe's (1965) study of Mugu Lagoon 

 and Ballona Creek marshes. During an 

 extensive trapping period in the early 

 1960's he found several residents of the 

 intertidal marsh (Table 17). Of these, he 

 studied the western harvest mouse 

 ( Reithrodontomys megalotis limicola ) , 



82 



