Wildlife

Goshawk nest in multi-top, 11” DBH pine
Goshawk nest in multi-top, 11” DBH pine
Juvenile long-eared owl perched near stick nest (used by owls but built by some other bird)
Juvenile long-eared owl perched near stick nest (used by owls but built by some other bird)
Basal hollow that extends 8-10 feet up into the bole of this 34” DBH Douglas-fir.
Basal hollow that extends 8-10 feet up into the bole of this 34” DBH Douglas-fir.

Wildlife use of damaged or deformed trees in managed forests

 By Bob Carey, Certified Wildlife Biologist, US Fish and Wildlife Service, Yreka CA.  Bob spent 15 years as staff Wildlife Biologist for a private forest management firm covering 300,000 acres in northeast CA and several years as a consulting wildlife biologist. 

Trees with deformities or other defects often provide important structure for wildlife.  Even trees that are not large can support raptors such as goshawks or Cooper’s hawks that often build stick nests in crooks or re-formed tops.  This is especially true when large old trees are uncommon in the remainder of the stand.  Forest- dwelling hawks may use several nest structures within one territory over a number of years.  Therefore, it is important to have an adequate number of potential trees available.  Owls do not build their own nests and often use platform nests constructed by other species.  Again, this is especially true in stands that lack large old snags with flat tops or large cavities that owls may use for nesting.  An “adequate number” depends on the landowner’s objectives regarding the balance between growing space and high quality wildlife habitat.  Each individual animal requires multiple sites (trees) within their home range and competition for sites among individuals may be high.  Mistletoe brooms also provide structure and many birds and mammals use mistletoe brooms as resting/nesting sites. 

The best option for wildlife is to retain all trees with indications of previous use (nest structures, excavated cavities, etc.), and work up from there.  Trees with candelabra tops, crooks, or witches brooms all provide important structure for wildlife.  Hollow trees and trees with cavities are also widely used and may be rare within the landscape.  The fungi that create heart-rot in trees that leads to the hollowing of the bole infects only live trees.  One of several indications of heart rot are large, black, hoof-shaped conks on tree boles.  Hollow logs will never form once the tree has died.  Fungi must enter the living tree through an opening in the outer bark that exposes the cambium.  Therefore, “skin ups” created during logging or trees damaged by windthrow can be retained to try to recruit more hollow trees (and logs once they fall) into managed stands. 

Defective, diseased, or deformed trees in intensively managed stands can act as a surrogate for the decadence that results over long periods of time in unmanaged stands.  These features are important to primary and secondary cavity nesters.  Primary cavity nesters actually excavate cavities (woodpeckers), secondary cavity nesters (swallows, wrens, other birds and small mammals) occupy holes formed by other species.  While “bigger is better” in most instances, small diameter trees also serve as a substrate for many arthropods and other animals that provide the base of trophic webs.  Decaying wood is fed on and inhabited by many insects and other small organisms.  These are fed on by amphibians and reptiles, birds and small mammals which in turn are prey for larger animals.  Generally, forest ecosystems are dynamic complexes that continually change through growth, death, decay and renewal.  All of the forest’s organisms rely on the other components to one degree or another.  Maintaining a balanced abundance and spatial distribution of all of the naturally occurring forest elements helps maintain the diverse array of organisms that comprise a healthy and ecologically functioning forest.   

 

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