The Fur Animals of Louisiana 369 



zone, the animals not thriving where tidal influence is too 

 .great but tolerating occasional inundation. These lands 

 are partly of alluvial origin and partly of coastal plain 

 formation. The muskrat territory east of the Atchafalaya 

 river is entirely alluvial in origin. West of the Atchafa- 

 laya it is largely of coastal plain formation traversed by 

 strips of alluvial formation adjacent to the streams of 

 that section. 



Climatic factors are, of course, similar on both sides 

 of the Atchafalaya river, as these lands lie in approxim- 

 ately the same longitude. There is relatively little differ- 

 ence in the rainfall in the different areas of south Louisi- 

 ana, although it averages slightly higher in the alluvial 

 section of southwestern Louisiana than in the coastal 

 plain section in the southwest. Periods of drought severe- 

 ly affect muskrats, particularly during the periods when 

 the marsh remains dry for long periods and marsh fires 

 take a heavy toll. These marsh fires do not seem to de- 

 stroy many of the muskrats by actual burning, since they 

 can seek refuge in the water, in their runways, or in 

 sloughs, lagoons, bayous, or canals which traverse these 

 areas, but by creating adverse alkaline conditions due to 

 potash salts from the burning of the grasses and peaty 

 humus. 



Rehabilitation After Droughts 



Subsequent to serious drought periods, it takes a 

 number of years for muskrats to rehabilitate a given area. 

 In some of the alluvial sections of Louisiana, particularly 

 near the mouths of the Atchafalaya and Mississippi 

 rivers and in St. Bernard and Plaquemines parishes, 

 where the marsh in the general vicinity of Delacroix 

 Island is kept relatively fresh by the waters from Lake 

 Pontchartrain and Lake Borgne, which acts as storage 

 reservoirs for the fresh waters of the rivers of the Florida 

 parishes, the rat areas are not as seriously affected by 

 the drought periods. 



On the other hand, in the areas between the main 

 rivers, such as in Terrebonne parish in the alluvial sec- 

 tions, or in the coastal plain areas in the western part 



