Of the mammalian species of interest, the raccoon is the most abundant 

 (USDI, 1976b^,£). Two other common brackish marsh associates are the niuskrat 

 and nutria. Less commonly encountered is the river otter. The coyote is 

 common to both refuges and is most frequently associated with the grasslands 

 where it subsists on a diet of cottontail, swamp rabbit, hispid cotton rat, 

 rice rat, and other small- to medium-sized prey. The bobcat has been encoun- 

 tered on the San Bernard Refuge, probably in association with the small wood- 

 land complex along Cedar Lake Creek. 



The productive tidal creeks, cuts, ponds, lakes, and other estuarine areas 

 support a very diverse biota and complex food web. The productivity of such 

 areas is well documented. Species composition and abundance is a function of 

 the season of the year, salinity regime, water depth, and accessibility from 

 Gulf areas. Cow Trap Lake contains numerous oyster ( Crassostrea virqinica ) 

 reefs. Other typical estuarine species in refuge lakes, ponds, and brackish 

 wetlands include the blue crab ( Callinectes sapidus ), young shrimp ( Peneaus 

 spp.), southern flounder ( Paralictithys 1 ethos tigma ), Atlantic croaker 

 ( Micropogon undulatus ), bay anchovy ( Anchoa mitchilli ), speckled seatrout 

 ( Cynoscion nebulosus ), and redfish ( Sciaenops ocellatus ). 



The American alligator, which occurs only on the Brazoria Refuge, is the 

 only threatened species in either refuge. This species is restricted to areas 

 of abundant surface water with well interspersed marsh vegetation. In such 

 shallow-water ponds, channels, and openings, the alligator becomes an efficient 

 predator of slower fish, turtles, nutria, muskrats, snakes, and whatever else 

 it can capture. 



Delta National Wildlife Refuge 



The Delta NWR is the site of some major oil and gas developments which 

 provide the federal government with more than one million dollars in mineral 

 revenues per year. The following is a brief description of the environmental 

 setting of the refuge. 



Location . Delta NWR is located on the east bank of the present "birdsfoot 

 delta" of the Mississippi River. The refuge lies in Plaquemines Parish, 

 Louisiana, about 121 km (75 mi) southeast of New Orleans; it occupies 19,749 

 ha (48,800 acres) of deltaic marshes, ponds, passes, and canals. Since its 

 establishment in 1935 as a sanctuary for waterfowl, it has been a popular 

 attraction for scientists and laymen; all visitors must drive to Venice, 

 Louisiana (the terminus of Louisiana State Highway 23) and proceed by boat 

 across the Mississippi River to the refuge headquarters. 



Geology, soils, and topography . The refuge lands consist of alluvium 

 deposited by the Mississippi River over the past three to four centuries. 

 Topography generally consists of low islands cut by numerous "passes," or 

 channels. The only solid ground is found on the natural levees occupying the 

 immediate banks of the passes. Land slopes downward from the top of these 



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