Speaking of Killdeer (1 Viewer)

I was sent a pic of a Killdeer on nest on top of a commercial building that has a gravel roof. Being Killdeer prefer nesting in gravel it seems natural they would build a nest on a roof top. I've also observed it's natural for the brood to be taken away from the nest area as soon as possible after the last chick has hatched to search for insects through the prairie grass and weeds.

Now for the question. How do the hatch-lings get down to ground level, or do they before flight feathers have developed?

Not sure how they'd climb over that parapet, but the newly hatched chicks are so lightweight they'd be able to jump down without any risk, even though they don't have any wings yet.

The advantage of the roof nest is the freedom from ground predators (dogs cats, etc.), the disadvantage the lack of food (if the chicks can't get over the parapet), and a slightly higher risk of avian predators (crows, etc.).

Agree, the problem is the parapet which I don’t see how the chicks could possibly surmount until fully flighted, leaving them, as you say, subject to starvation or death by avian predator. Crows in particular would be a problem. In places where they’re common, as they are in many North American towns and cities nowadays, mortality would likely approach 100%.