8 



NORTH AMERICAN FAUNA 66 



and white pine are occasionally encountered on the slopes and in the 

 valleys, but deciduous trees predominate. These include sweet birch, 

 sugar maple, red maple, black cherry {Prunus serotina), basswood, 

 beech, shagbark hickory {Gary a ovata)^ white oak, and northern red 

 oak. On higher ridges, northern red oak and red maple predominate, 

 with chestnut oaks, black oak, and yellow birch {Betula lutea) inter- 

 spersed. Scattered red spruce {Picea ruhens) is sometimes also found. 

 In valleys above 2,400 feet, there are some relict bogs consisting of 

 sedge meadows and bog heaths interspersed with patches of alder 

 {Alnus sp.), great laurel {Rhododendron mouxirrmm) ^ red spruce, 

 hemlock, yellow birch, and red maple. 



MARYLAND'S MAMMALIAN FAUNA 



These biotic sections of Maryland are not sufficiently differentiated 

 to support widely divergent mammalian populations. Some forms are 

 confined to one or two sections of the State, but in general the mam- 

 malian fauna does not differ greatly from section to section. The 

 average- fauna formula (Long, 1963) discussed below, reveals that 

 the most significant division in the State is between the Piedmont sec- 

 tion and the Eidge and Valley section. The most diversified mam- 

 malian fauna is in the Allegheny Mountain section, the most impov- 

 erished in the Eastern Shore section. 



Long (1963, p. 139) recommends the average- fauna formula, 2(7 

 (100)/(Ni-f-N2), for deriving a numerical expression of the faunal 

 resemblance of one area to another (in this formula, 6^= number of 

 kinds common to both faunas, = number of kinds in smaller fauna, 

 iV^2= number of kinds in larger fauna). Using this formula, and sub- 

 stituting the number of species and subspecies for each section of 

 Maryland, the following comparisons were obtained : 



Western Piedmont Ridge and Allegheny 

 Shore Valley Mountain 



Eastern Shore 



Western Shore 



Piedmont 



Ridge and Valley. 



90 83 73 62 



92 77 67 



83 68 



S7 



These percentages show, as is to be expected in an area of this small 

 size, that the mammal fauna of all the sections of Maryland rather 

 closely resemble one another. Naturally, the most distant sections of 

 the State geographically and ecologically, the Allegheny Mountain 

 and the Eastern Shore, differ the most faunistically. Nevertheless 75 

 percent of the species and subspecies are common to both sections. The 



