Size and Distance to Water of Trees Felled by Beaver in the Central Adirondacks

Jennifer Marshall

 

Introduction
Beavers leave the water to fell trees and transport them back to their ponds for eating.   By doing so, beavers act as central place foragers - animals that collect food and store it at a fixed location in the home range (Jenkins 1980).  Beaver forage more selectively at increasing distances from their “central place” (Muller-Schwarze 2003).  Identifying patterns in tree felling selection by beaver is important to understand how beaver impact forest change in the Adirondacks.  I investigated the relationship between size of trees cut by beaver and distance to the edge of the nearest water body.  

Methods
Five sites with active beaver colonies were examined on Huntington Wildlife Forest in the central Adirondacks.  I measured both felled and live tree diameter on 78 transects that were each 3 m wide and 80 m long and ran perpendicular to the shoreline.    


Results and Discussion
The maximum distance felled trees were found was 111m (354 feet). As distance from shore increased, tree diameter of beaver felled trees further decreased (Figure 1). 

Figure 1 Max Diameter of Trees and Distance to Water

For tree species preferred by beaver, such as beech, sugar maple and ash, numbers of live trees increased as distance from the shore increased.  The results are consistent with an optimal foraging model of size-distance relations in which pursuit of provisioning time depends on size of food as well as distance.  I did not find any felled or live quaking aspen, the tree that in many areas is the beaver’s favorite species.  This suggests beaver may have to resort to other tree species for food that would not normally be their first choice, because the food resources that they depend on are exhaustible. 

 

 

Literature Cited
Jenkins, S.H. 1980. A size-distance relation in food selection by beaver. Ecology 61:740-746.

Muller-Schwarze, D. 2003.  The beaver: natural history of a wetlands engineer.  Cornell University Press, Ithaca, NY. 190 pp.

Contact: Adirondack Ecological Center- aechwf@esf.edu

About The Author: Jennifer Marshall is a Junior in the Department of Natural Resources at Cornell University’s College of Agriculture and Life Sciences.