The last place you want creatures to nest is inside your roof, but the rooftop itself might make for a friendly compromise. These out-of-the-way compartments might make bird waste a wee bit harder to remove, but at least let fowl have free reign on that extra top ‘floor’ you do not use anyway.
These little bird homes were designed by Klass Kuiken to nest (no pun intended) within a standard system of rounded red tiles, overlapping on both sides, above, and below to fit into an existing system of modular rooftop elements and made of the same material.
While these examples show a here-or-there approach, a place with a great many birds passing through could really start to layer these on as an element within the overall design (as opposed to an aesthetic exception to the apparent rooftop rules). The big catch: can you get it to match your real vintage roof tiles? On the flip side, though, they might just be perfectly out-of-place replacements for hard-to-match antique shapes and colors.