EXPLORING
BEAVER HABITAT WITH GOOGLE EARTH:
BEAVER ENGINEERED LANDSACPES- THE HIGHEST DENSITIES OF BEAVERS IN CANADA
Beavers played a key role in the settlement and development of Canada. Beaver
pelts drove the economy and formed the "currency" for the trade between
the Hudson Bay Company and the aboriginal nations in Canada.
The beaver population steeply declined under the pressures of over trapping and
reached a threatened species status. Presently beavers are reclaiming
much of their original habitat, at least what is left of it. In many
areas this recovery is rather spectacular. This recovery is captured
by comparison of old Aerial Photography with recent high resolution
Google Earth imagery
The north american beaver, with its beaver dams, beaver lodges and ponds is unique
in the sense that it provides a clearly visible footprint on satellite
images, particularly the high resolution imagery accessible through
Google Earth ( i.e. Digital Globe, SPOT et.)
Using extensive photo interpretation of Google Earth and Aerial Photo images
(See the National Air Photo Library on-line site), I have identified a number of unique perspectives, superlatives related
to the lengths of beaver dams, unusual high densities of beaver populations.
This page report on the highest beaver concentration in Saskatchewan
and possibly the world.
Pakwaw
Lake Beaver Community,
Saskatchewan , Canada
. This high resolution Google Earth (Digital Globe) shows an unusually high
concentration of the beaver dams. The highest I have observed
in
Canada
(in
the
world?).
Over
20
dams
and
lodges
per Km2. The
beaver lodges are clearly visible as light dots (actual size
on the ground is 7-8
meters
in size) in the inundated areas. It is typical to find high densities
of dams in streams (10 - 25 dams per linear Km) but is is rather
unusual to find them evenly spread out over a wetland like this.
This image shows a portion of a large beaver community near Pakwaw
Lake (see below)
Figure 1 (larger version+)
|
| |
Figures
2 and 3
This NASA World Wind Pseudo Colour Landsat Image (2000) shows the broader landscape
setting of this high density beaver area. The near infrared enhances
the beaver ponds (small dark blue spots creating a loosely knitted
landscape impression. The white square represents the approximate
location of the Google Earth image above. The thin red lines
outline the concentrations of beaver dams in the landscape. The
Pakwaw Lake first nation's community is to the left of the square. 
|
| |
 |
|
| |
Figure 4
The image below is a 1990 NASA Landsat Image.
There are no major differences with the Landsat 2000 image. In
1990 the water levels are higher. The dark blue bog areas have become
marginally smaller in some areas (pink on the 2000 Landsat). In some
areas there appear to be more beaver dams in 2000, but some of this
may be the result of the slightly better resolution of the 2000 Landsat
image. |
 |
| |
Figure
5 a and b
There is a dramatic difference between the
1945 air photo (right) of the same area as the Google Earth image
(left). There is certainly no larges scale presence of beaver
in 1945. Tree cover
at
that
time was
probably
birch
and aspen with alder and willow shrubs and some open wetlands.
In the surrounding area some signs of beaver activity were seen. |
 |
 |
| |
Figure
6
This
topographic map shows the Northern Woods and Water Route which
crossects this beaver landscape. The this Highway follows one
of the glacial lake Agassiz beach lines, which are quite prominently
on the Landsat images as a series of parallel linear landscape
features, similar to the countour lines on the topographic map.
|
