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Beaver Life History & Biology
Dr. John StellaAnna Harrison
SUNY ESF19th September 2011
The Colony• Family/colony unit (6-8 related individuals)• Active colonies spaced at least 0.25 miles from other
colonies • Mark territory with scent mounds
Love of the water• Lodge is the central place for a beaver colony• Beaver more agile in water than on land• Aquatic habitat protects them from predators• Attempt to maximize time in water, minimize time on land
Food preferences• Spring/Summer diet: herbaceous, aquatic vegetation• Fall/Winter diet: trees and tubers• Beaver collect food for winter in food cache, store next to lodge
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Initial site establishment• Well established drivers (Bradt 1938) that create largest
possible pond area:– Low stream gradient– Small stream cross-sectional area
Beaver site establishment
• Dams also built as ‘safe’ transportation corridors to connect large ponds
Beaver site establishment• Ultimate purpose of dam: location for lodge
Beaver Impacts: landscape change• Beaver change landscape from terrestrial to aquatic• Most landscape change occurs in first 20 years of
occupancy
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Beaver impacts: increase wetland area
• Greater landscape diversity– Wright 2002
• Waterfowl habitat• Amphibian habitat– Karraker and Gibbs
2009
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Pond
MeadowOld Pond
Stream
Naiman 1988
New PondBeaver impacts: Possible beaver pond succession post abandonment
Beaver impacts: forest structure
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• Trees used for food and dam/lodge building resources
• Beaver can ‘clear cut’ areas with young trees
Beaver impacts: forest structure• Remove understory and canopy trees• Open areas up to shrubby species
Beaver Impacts: foragingGeneralized Central place foraging model
P
Distance from the impoundment
Sele
ctivi
ty
Non-preferred
Opportunistic
Most Preferred
Ecosystem Engineer slides
I’m not sure if/where you’ll want to use these, but they are a good example of
culvert blockage, flooding, dam removal and beaver deceiver at HWF
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Ecosystem engineer
Photo: Adirondack Ecological Center
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Ecosystem engineer
Photo: Adirondack Ecological Center
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Ecosystem engineer
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Ecosystem engineer