Part 11 (1/2)
Bats of this monotypic genus occur on Bougainville, Choiseul, Santa Ysabel, and Guadalca.n.a.l (see Fig. 4). These four islands probably were contiguous during the maximum lowering of sea level in the Pleistocene (see Durham, 1963:362-363). Bats of the genus _Pteralopex_ are the only kind in the Solomons having a distribution that can be correlated with former land connections between islands.
The distributions of 16 species of megachiropterans known from the Solomons are summarized in Table 5 and in Figure 16. The larger islands (in terms of surface area and elevation) in general have the highest number of species (Guadalca.n.a.l 10, Choiseul 9, and Bougainville 8). But Fauro, one of the smallest islands for which data are available, has six species of megachiropterans whereas San Cristobal and Malaita, two of the larger islands, have only three and four species, respectively.
Possibly this difference signals the need for additional collecting.
Bougainville and Choiseul, about 60 miles apart, have seven species of megachiropterans in common (Table 5). Fauro, 25 miles southeast of Bougainville and 35 miles west of Choiseul, shares five species with each of these islands (Fig. 16). _Pteralopex atrata_ and _Pteropus rayneri_ occur on Choiseul and on Bougainville, but not on Fauro.
Individuals of these species are the largest fruit bats in the Solomons, and their absence on Fauro suggests, therefore, that this small island is ecologically unsuitable, at least in some months, for the support of populations of bats that require relatively large amounts of food. The small size of the island is consistent with this hypothesis, but several other islands as small as Fauro do support populations of the large kinds of _Pteropus_, at least in some months.
TABLE 5. A Summary of Distribution of All Species of Megachiropteran Bats Known from the Solomons. Only Islands Well Known Faunistically Are Listed.
Column headings:
A: Bougainville I: Vella Lavella B: Choiseul J: Kolombangara C: Santa Ysabel K: Russell D: Ndai L: Guadalca.n.a.l E: Malaita M: San Cristobal F: Florida N: Ugi G: Fauro O: Rennell H: Shortland P: Ontong Java
===================+==+==+==+==+==+==+==+==+==+==+==+==+==+==+==+== SPECIES
A
B
C
D
E
F
G
H
I
J
K
L
M
N
O
P -------------------+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+-- R. amplexicaudatus
X
X
X
X
X
X
X
P. atrata
X
X
X
X
Pt. hypomela.n.u.s
X
Pt. admiralitatum
X
X
X
X
X
Pt. tonga.n.u.s
X
Pt. howensis
X Pt. rayneri
X
X
X
X
X
X
X
X
X
X
Pt. woodfordi
X
X
X
X
Pt. mahaga.n.u.s
X
X
D. inermis
X
X
X
X
X
X
X
X
X
X
X
X
M. lagochilus
X
X
X
X
X
X
X
M. woodfordi
X
X
X
X
X
X
M. aurantius
X
X
N. albiventer
X
X
X
X
X
X
N. major
X
X
X
X
N. malaitensis
X
+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+-- Totals
8
9
6
1
4
4
6
4
3
5
4
10
3
2
3
1 -------------------+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--