1918] Grinnell: A Synopsis of the Bats of California 233 
southward movements of the silvery-haired or hoary bats in the east, 
but he records the occurrence of the former species about the hght- 
house on Mt. Desert Rock, thirty miles off the coast of Maine, in 
spring and fall. On this treeless islet bats are at other times un- 
known. 
Seton (1909, p. 1175-1176) states that on the Red River at Win- 
nipeg he has found the silvery-haired bats common from the vernal 
equinox until about September 21, after which they are neither seen 
flying, nor found in their accustomed daytime haunts. 
The hoary bat breeds only in the boreal zone of North America, 
but it has never been recorded in this zone in winter. In winter it 
occurs regularly at least as far south as the southern border of the 
United States. It has been taken on the Bermudas, showing that it 
is able to cross a strip of ocean having at its narrowest extent a width 
of over six hundred miles. It is, however, as suggested by Miller, 
much more likely that the bats commence their ocean journey at 
some point much farther to the north, such as Cape Cod, the distance 
from which to the Bermudas is about seven hundred miles. Of this 
bat’s occurrence in the Bermudas, J. M. Jones (1884, pp. 145-146) 
‘ 
says that it ‘“‘is observed occasionally at dusk during the autumn 
months hawking about according to its nature in seareh of insects; 
but as it is never seen except at that particular season it is clear that 
it is not a resident, but merely blown across the ocean by those violent 
northwest gales which also usually bring numbers of birds from the 
American continent.’’ The latest date at which Seton has recorded 
hoary bats in Toronto is mid-September. Major Mearns (in Howell, 
1908, p. 37) records a diurnal flight of hoary bats at Fort Snelling, 
Minnesota, but no details are given. 
In regard to the red bat, Seton (1909, p. 1189) says that in sum- 
mer, in Manitoba, this bat roosts in trees, it is solitary, and is not 
known to frequent caves. ‘‘In winter it is known to gather in vast 
numbers in the caves of its more southerly range.’’ Seton gives no 
authority for the statement that this bat hibernates in caves, and I 
can find no confirmation of his statement in accounts by other writers. 
In southern California where the red bat is often found in evergreen 
trees in winter it has never, so far as I am aware, been found in caves. 
Writing from the Hudson Highlands of New York, where this bat is 
very common in summer, Mearns (1898, p. 345) says: ‘‘During the 
latter part of October and the first week of November, I have seen 
great flights of them during the whole day. In 1876 I noted that all 
