A family of beavers has moved into our back yard and built several dams along a small ditch which runs into Mitchell Creek. Al was fine until they girdled a 20 foot willow which could cause some damage if it falls the wrong way. Its been over a week since the tree attack. Is it possible they will leave it like this or do they fall these trees later?
The beavers may or may not return to that tree. If the tree is completed girdled, it may not survive, regardless of further interaction with the beavers. It would be a good idea to upload photos so we can bring in expertise from one of our Forestry experts. For other trees you want to protect, it would be a good idea to wrap their lower trunks with welded wire mesh so that they won't also be girdled or felled.
If you're thinking of reducing the local population or altering their structures (dens, dams), you should consult with your District Biologist from Oregon Dept of Fish and Wildlife (ODFW Clackamas Office at 971-673-6000 or Sauvie Island office at 503-621-3488). Population reduction is a temporary fix at best because the habitat opportunity will be discovered by other beavers. However sometimes reductions (usually lethal but relocations rarely) can be managed to maintain a certain level of activity. Beavers on private land can be removed without a permit - Trained and licensed Wildlife Control Operators https://www.dfw.state.or.us/wildlife/license_permits_apps/wildlife_control_operator_contacts.asp#WCO...can be one option to consider. There's alot of beaver information in this document provided by ODFW https://www.dfw.state.or.us/wildlife/living_with/docs/beaver.pdf