Upon arriving the darker bird was foraging below the bridge and after gathering food it flew up to the nest. This happened a few times with approximately 3 feeding per 5 minutes over a 15 minute period. The bird then stopped and preened for a few minutes. I could see that the other adult was in the nest when i peeked under the bridge.
About 20 minutes after I arrived the other lighter throated adult emerged from the nest carrying a fecal sack and then proceeded to fly off downstream.
The darker bird stood under the bridge for a couple of minutes and then flew up into the nest. It stayed for close to 10 minutes before emerging. It then flew some distance downstream out of sight. Upon returning about 5 minutes later it had a mouthful of food and it fed the young. It then returned to foraging near the nest feeding often over the next ten-fifteen minutes.
After all this time the lighter bird returned from downstream without any food and after a minute or so it flew up to the nest.
The darker bird went back to its feeding routine.
After another 5 minutes the lighter bird emerged from the nest and headed downstream.
The dark bird stood under the nest for an additional 5 minutes before also flying off downstream.
I waited another 10 minutes and no adults returned and then I left.