Table 16. Breeding pairs of Belding's 

 savannah sparrows in southern Calif. From 

 Massey 1979. 



No. of Pairs 



Location 



Tijuana Estuary 

 South Bay Marine Reserve 

 South Bay salt ponds 

 E Street Marsh 

 Sweetwater Marsh 

 Paradise Creek Marsh 

 Beacon Island (in Mission 

 San Diego River Marsh 

 Mission Bay Marsh 

 Los Penasquitos Lagoon 

 San Dieguito Lagoon 

 San Elijo Lagoon 

 Batiquitos Lagoon 

 Agua Hedionda Lagoon 

 Buena Vista Lagoon 

 Santa Margarita River 

 Upper Newport Bay 

 Huntington Beach 

 Bolsa Chica 

 Huntington Harbor & 



Sunset Aquatic Park 

 Anaheim Bay 



Los Cerritos Wetland Chanr 

 Playa del Rey 

 Mugu Lagoon 

 Ormond Beach 



McGrath Beach State Park 

 Carpinteria Marsh 

 Goleta Slough 



meadow mouse ( Microtus call f ornicus 

 stephensi ) and feral house mouse ( Mus 

 musculus ) populations in detail. All 

 three were frequently trapped at Ballona 

 Creek, while feral house mice were only 

 found in areas adjacent the marsh study 

 site at Mugu Lagoon. Absence of Mus 

 musculus was suggested as being important 

 to the occurrence of the deer mouse 

 ( Peromyscus maniculatus ) at Mugu Lagoon, 

 since others have shown feral house mice 

 to be aggressive competitors Coulombe 

 (1965) found that the feral mice at 

 Ballona Creek underwent radical changes in 



population size, from a peak in December 



1962 to a crash by April 1963; a much 

 smaller peak population occurred in 

 October 1963 with another decline by 

 February 1964. These data may bear on the 

 question about drowning — perhaps the 

 exotic species cannot avoid the problems 

 posed by high spring tides. The native 

 meadow mice also increased in December 



1963 and crashed by July 1964. However, 

 the western harvest mouse apparently copes 

 very well with its intertidal environment; 

 its populations were remarkably stable at 

 both sites. This in turn raises the 

 question of how they maintain their 

 densities while other species fluctuate 

 widely. Coulombe (1965) suggests only 

 that social interactions may be important, 

 since he could not establish causes of 

 mortality for either young or adults. 

 The diets of the two native species differ 

 somewhat. Meadow mice are primarily 

 herbivorous, while harvest mice are 

 granivorous. Coulombe's feeding 

 experiments indicated that neither species 

 can feed on pickleweed. Mortality may 

 have been due to the high chlorine (1.8 x 

 sea water) or other ion concentrations, or 

 to toxic substances such as oxalates 

 Coulombe (1965). This also means that 

 mice cannot use pickleweed as a source of 

 moisture, although MacMillen (1964) found 

 that the western harvest mouse could drink 

 sea water and release highly concentrated 

 urine. Coulombe (1965) suggested that dew 

 provides a water source, but that 

 long-term survival may be due to the 

 mice's ability to tolerate periods of 

 moisture stress; the meadow mouse by 

 tolerating dehydration and the western 

 harvest mouse by going into torpor (a 

 temporary period of low metabolic rate) . 



5.6 SUMMARY OF CHAPTER 5 



This chapter describes a number of 

 animals which are uniquely adapted to life 

 in a fluctuating environment. Although we 

 do not understand fully how they cope with 

 the salt marsh habitat, we realize that a 

 number of species are dependent on the 

 marsh and several have neared extinction 

 as marsh habitats have been eliminated. 



83 



