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