We have a beautiful cat named Leo. Whenever we brush him, we collect his hair and keep it in a zip lock bag. When spring comes, we tie it to a tree branch in our backyard so that the birds can come and collect it for their nesting material.

In our vegetable garden, we usually tie the vines with yarn because I always have some leftover yarn from my knitting projects. Once the planting season is over, while cleaning up the garden, we purposely leave some of the yarn tied to the trellis. When spring comes, the birds will come and collect these yarns. Mostly, the chickadees and goldfinches are the ones that use them a lot. I love watching them as they pull hard to collect it in their beaks and fly away happily.
And after some time, we can see them coming with their babies in the garden.

If you want to do the same thing in your garden to help these birds, the yarns and cat hair must be tied tightly as they like it that way. Here is the video on how they collect.