https://www.canr.msu.edu/resources/building_and_managing_bee_hotels_for_wild_bees_e3337
https://nestwatch.org/learn/all-about-birdhouses/birds/house-wren/
https://extension.okstate.edu/fact-sheets/three-designed-birdhouse-plans-for-eastern-bluebirds.html#mounting-and-placement-principles
