Exploring Beaver Habitat with Google Earth

Beavers are rather interesting and very experienced managers of water. In Northa America they have a wide range of distribution, which seem to be expanding in all frontiers: the north for example and in many suburban and urban environments.

Our interest is in the most norther edge of their distribution in North America. Why the beaver? They leave a footprint on the envronment which is relatively easy to interpret from high resolution satelite and airborn imagery. Can beaver migration be an early indicator of habitat response to climate warming?

Beavers are typically boreal and temperate species living in habitat surrounded by trees which provide a good food supply. The Northern Limit of the Beavers is interesting since beavers seem to follow climate warming trends (not just the last decades, but are migrating north since the little ice age, the last period of climate cooling a few hundred years ago). With the acceleration in warming, the rate of migration into the subartcic may accellerate along the rivers and streams where they live of willow and alder.
Apparently Moose and Red Fox are also moving into the subarctic, but their "foot print" is not visible on a satellite image. Google Earth with its incredible ability to scale into high resolution detail makes beaver activity and possibly its migration north "mappable"

The range of the beaver is typically shown in map on the right. A fairly large generalized area which usually shows the maximum area of the species distribution reported. The reality is a frontier which is far more intricate and complex than the edges of the map theme suggest.

 

North American Distribution of Castor Canadensis

source: Hinterland Who's Who

The image above shows some of the sites which have been studied using high resolution imagery available through Google Earth. Some of these sites are includes in the examples below

 

This shows a typical example how beavers manage water in wetlands in Northern Canada when they are relatively undisturbed. The image below gives a simple interpretation of the area. This area is part of the northern edge of the Boreal zone. Pieces of precambrian bedrock are visible as "islands" in a large wetland area. Most of the watermovement is in the form of "ground water" flows in the wetlands, and the beavers had to build extensive dams to contain the flow. The resolution seems adequate to identify some of the possible beaver lodges. Below is a typical cross section, source: Hinterland Who's Who

Google Earth Link: Water management and beavers