I watched this pair (already on eggs (4) for about 21 days). The nest was built on a nearby driveway on open gravel, as they usually do. As I’s pushed closer to the nest, the pair would go into defensive mode. The female would always come at me but stop short by 10-15 feet. The male would feign injury or death across the driveway to get my attention or draw it away from the female and nest. It seemed 30 feet was the threshold. When I moved away to further than about 30 feet; she’d nestle gingerly back onto the eggs, and he’d leave the area.
I did this 2-3 times per day for 8 days, always hoping to catch that moment when the eggs started to hatch. I missed. The hatched and the hatchlings were gone the very next morning. The long incubation period allows the chicks to fully develop and are ready to run or even fly within 1-2 hours after drying off. I did take over 1000 photos.
Pictures follow; had to use a very long lens:
Life and Wildlife along the Little Buffalo River 