We have lived in our house for nine years. The only wildlife that deigned to live on our back porch were these bees or wasps, who would actually drill into the wood of the porch.
So when my wife complained that I had tracked some grass onto the back porch back in May, I had no idea what the heck she was talking about. It turns out that there was a couple birds, male and female, building a nest on a narrow rail above the front porch. I should restate: actually, they were building three or four nests. But all but one were ultimately abandoned, but the vacated nests were eventually used to fortify the chosen dwelling. This rail is only about three inches (7.5 cm) wide, though the nest itself is about five inches (12.5 cm) in diameter; very well designed, I'd say.
Eventually, eggs must have been laid, although I couldn't see from that angle; there's only about a half foot (15 cm) from the top of the post to ceiling of the porch. Generally, one or the other bird would be hanging out at the nest the vast majority of the time. Although when I would open the back door and the smaller adult bird was awake, sometimes he or she would fly away for a time, but not too far.
Ultimately, we saw three baby birds being fed by their parents. But before too long, the birds were gone, leaving behind only the nest and purple poop on the porch. We're still unclear as to why they chose our home as their temporary residence, but it was fun while it lasted.