Not the Brightest Bulb in the Box

This is mama Eastern phoebe. She's sitting on eggs - a second clutch, I think - on a different nest than usual. This nest is almost three stories up. Three stories. Atop the drainpipe that runs from the roof down past the garage door. The last time they tried this the ending wasn't pretty. Two nestlings ended up dead on the cement step below. We're wondering if we could put something underneath the nest that would catch anything that fell rather than flew out... Difficult to say what we'd do or how we'd do it. At the moment the eggs aren't hatched, so there's still time to figure something out. But of course, if we mess around too much she might just abandon the eggs and nest.