Feldtmann, Houghton, and Red Oak. All 
are more precipitous on the northwest 
faces, while the southeast slopes are 
usually quite gentle. The highest 
elevation is Mount Desor, 1,394 feet 
above sea level and 792 feet higher 
than Lake Superior (602 feet). 
Between the numerous ridges are 
38 named lakes and about as many un¬ 
named ponds. Siskiwit Lake, 7 miles 
long and about 140 feet deep, is the 
largest and deepest. There are five 
major streams and many intermittent 
ones. Sheltered coves and deep, 
fiordlike harbors offer good pro¬ 
tection along much of the shoreline, 
especially in the northeast and 
southwest sections. 
The climate is typical of the 
upper Great Lakes area, with cool 
summers and severe winters, although 
temperature extremes are modified by 
Lake Superior. Ice bridges sometimes 
form in winter between the island and 
the Canadian shore, and the open 
southeast side of the island is usu¬ 
ally trimmed by a shelf of ice a few 
yards to a mile wide. Snow depths 
have exceeded 3 feet, but 2 feet may 
be more normal. 
The island was completely gla¬ 
ciated, and there has been no direct 
overland access to the island since 
the glacial retreat. This has meant 
that invasion by terrestrial organisms 
has been only through circuitous means. 
Most birds, bats, and organisms dis¬ 
persed by wind and water have been 
successful colonizers. Because of 
the island's isolation, many mammals 
typical of the region are missing. 
Among these are the white-tailed 
deer, black bear, porcupine, skunk, 
raccoon, and most of the small mammals. 
The coyote was numerous in the 
1940's and early 1950's but became 
extinct about 1958, possibly because 
of competition by the timber wolf, 
which first appeared (at least in 
this century) about 1949. Woodland 
caribou were present until about Ijjj 
when they disappeared, probably be¬ 
cause of habitat changes. Marten and 
Canada lynx, both present at the be- 1 
ginning of the century, disappear®! * 
for unknown reasons. Last reporta &f J 
marten were about 1905, of lynx about c 
1935. Recent reports suggest the f 
possibility that lynx may have estafc* l 
lished themselves during the 1962-61 1 
winter. ’j 
Mammals present now include the 
moose, beaver, mink, otter, and musk* ( 
rat, which may have reached the is* 1 
land by swimming. The moose has alio 1 
been reported to have reached Isle J 
Royale via an ice bridge between the 1 
island and the north shore of Lake 1 
Superior during the winter of 1912-13 1 
(12). The timber wolf, red fox, and 
snowshoe hare probably crossed on an 1 
ice bridge. The red squirrel, whit#* 
footed mouse, and two species of 
weasel, whose means of access are 1 
less easy to visualize, may have used 1 : 
floating debris or possibly had help 
from man. 
* 
' 
Five species of bats, nine 
amphibians, and three reptiles have 
been recorded. Several other speci#S 
of reptiles and amphibians that occur 
around Lake Superior have not been 
found on Isle Royale. 
In the avian fauna, the only 
conspicuous absences are the ruffed 
and spruce grouse. There would 
seem to be adequate habitat for 
these birds on the island, but nei¬ 
ther species has ever been recorded 
there. The inability of these grouse 
to fly long distances probably has 
prevented their colonization of Isle 
Royale. Sharp-tailed grouse now in’* 
habit the island and are known to 
have been present for about a cen¬ 
tury. 
2 
