Can you help with these worms/caterpillars on our tree
Thanks for your question about the caterpillars on your tree. (It appears to be a madrone.) The insects appear to be tent caterpillars, although they don't look like either of the two species most common in the Pacific Northwest (including Central Oregon.) Here's a link to an OSU article about them and their life cycle. Note that the outbreak doesn't occur every year, and that their damage to your tree is only aesthetic. Having said that, I can't tell from the photograph of the tree, nor your description, whether other problems plague your tree. The caterpillars will soon become moths and leave, and another egg mass will not be laid for a year. If your tree was denuded of foliage before the eggs matured into caterpillars, and began eating, you should research other issues.
Hope this is helpful. Good luck!