I once went to a volunteer event to tag monarchs for science/migration purposes. I caught one, and was so stressed that I was going to hurt it, but it all ended up okay! It was both a lot of fun and sad that there weren't as many anymore.
I'm planning on having my backyard partially redone this summer, and I'm hoping my new garden will help the local population more; my contractor is someone who specializes in local, sustainable plant life, so he asked if he could take out a bush that's apparently an invasive species.