growing season in most years. Emergent plant cover is subdivided into 

 persistent and nonpersi stent categories. Persistent emergents remain stand- 

 ing until at least the beginning of the next growi no season. Nonpersi stent 

 emergents fall to the surface of the substrate at the end of the crowing 

 season and there is no obvious sign of vegetation during part of the year. 



Woody vegetation taller than 6 m (20 ft) is defined as forest, and 

 shorter than 6 m as scrub-shrub. Scrub-shrub includes young trees, true 

 shrubs, or trees and shrubs that have been stunted due to adverse environ- 

 mental conditions. Both forest and scrub-shrub classes are divided into five 

 subclasses: broad-leaved deciduous, needle-leaved deciduous, broad-leaved 

 evergreen, needle-leaved evergreen, and dead plants. 



Palustrine forested and scrub-shrub areas are separated on the basis of 

 the percent covered by the uppermost life form (i.e., forest). Thirty per- 

 cent coverage is considered the "threshold" for designation. In other words, 

 if an area has 40% forest canopy over 70% scrub-shrub understory, the area is 

 designated forest. If there were 20% forest over the same 70% scrub-shrub 

 understory, the area would be designated scrub-shrub. If forest and 

 scrub-shrub are less than 30* alone, but together comprise 30% or more, the 

 area is designated scrub-shrub. Palustrine and scrub-shrub areas are mapped 

 together as a single unit for the purpose of this study. 



The areal wetland data for the 1 : 100,000-scale maps provided in the Atlas 

 were derived from analysis of the 1:24,000 National Wetlands Inventory maps. 

 Acreages for each wetland category were calculated from the 1 :100,000-scale 

 atlas maps using a dot grid, which is a statistical area measurement tech- 

 nique. In Mobile and Baldwin Counties the total wetland acreage was calcu- 

 lated to be approximately 692,000 acres, or about 38% of the two counties 

 total area. Of the three categories mapped, palustrine forest and scrub-shrub 

 was predominant with 621,000 acres in this category, or about 34% of the area 

 mapped. Estuarine emergents totaled 61,000 acres and palustrine emeraents 

 only 10,000 acres. Thus, these two categories together were less than 4" of 

 the total acreage of Mobile and Baldwin Counties. 



BIRD RESOURCES 



Seabirds and Wading Birds in Coastal Alabama 



The mapped locations of nesting sites for qui Is, terns, and wading birds 

 are from Johnson (1979), Portnoy (1977), 0'Neil and Mettee (1982), and the 

 U.S. Army Corps of Engineers (1983). The most important coastal bird nesting 

 areas occur in Mississippi Sound and southwestern and southeastern or lower 

 Mobile Bay (Figure 1 and Table 1). Nesting sites tend to chanae over tine; 

 thus, those listed and mapped should be considered as only a general guide. 



The most important nesting site is Cat Island (Biloxi quadrangle), which 

 in recent years has supported colonies of the following wading birds: cattle 

 egret ( Bubulcus ibis ), great egret ( Casmerodius albus ), snowy egret ( Egretta 

 thula ) , reddi sh egret ( Egretta rufescens ) , green- backed heron ( Butorides 

 striatus ) , tricolored heron ( Egretta tricolor ) , little blue heron " TEgretta 

 caerulea) , glossy (Plegadis falcin eTTusl and/or white-faced ( P. chihi ] ibis. 



