Number of fledglings?

It seems that the number of young herons present at the rookery has dropped. So I asked Susan, who lives a block away, for this first-hand account:

"On July 11th my brother and niece came to visit. We decided to walk over to the heron rookery just around the corner from my house. Sierra had never seen anything like it before and was excited to see a heron way up in the alders and maples. It was a little hard for her to see them so high above. Along the dirt road near the open clearing we discovered grey feathers, feet and a beak; the remnants of an unlucky heron that had been a predator's meal. Then, as we were peering into the trees to see the wide gray areas on the ground as clues to which trees have nests, we spotted a heron standing on the ground. What a discovery for an 8 year old! It was staying very still, probably trying not to be noticed. We started speculating as to what it might be doing. Could it have survived a fall from the nest? Possibly. Did it land and walk down there on purpose? It didn't seem likely. We had questions. Would it learn to fly? Was there enough room between the trees for those big wings to spread out? How long had it been there? Was it hungry? We wondered if it needed some urging to get out in the open where it might be possible for it to try flying. We decided to go into the woods to get a better look, even with the risk of being covered in those fishy smelling gray droppings that cover the ground under each nest. We didn't get too close to the heron, but we made our way through ivy and fallen limbs past the heron. It certainly watched us and started to move away if it felt we were headed towards it. Once we were past, we started moving in its direction to herd it out to the cleared area next to the rookery. Watching those long legs from 20 to 30 feet away was amazing. They have an awkward grace when on the ground. At one point the bird opened its wings and lifted about a foot off the ground, but went back to walking. Once it was out in the open we stopped to see what it would do. It moved away from us in the open, then went back into the cover of the trees. Oh, well. I guess it wasn't going to fly that day. We went home. There, a neighbor showed us the heron shells she had collected under the nests when the chicks were hatching as the pieces were kicked out of the nest. They are a light blue and seemed to be just slightly larger than a chicken egg. We all wondered about that heron for the next week. How was it doing? Would it survive? The next Saturday, July 18th, my brother's whole family came for a visit. Both my nieces this time. We walked to the rookery to see if our grounded heron was still there. We didn't see it. Jessica was disappointed that she didn't get to see it after listening to Sierra's stories all week long. We did see some herons in their nests in the trees. We got to hear their odd, prehistoric sounding calls. We talked about the predators that they have to contend with. From the sky they are attacked by eagles, hawks, and at night, owls. From the ground there are raccoons. As we walked further along the dirt road Sierra noticed something out in the open clearing, "Look! I think something got a heron!" She was right. Up ahead we could see the blue feathers and something bright red. We wondered if it had been our heron in the woods from last week. The girls wanted to see it, even though it might 'gross them out.' Most of the bird was eaten, just feathers, feet, head, beak, and a little muscle tissue still attached to some bones remained. We could tell that this happened just recently. The muscle tissue wasn't even dried out. We had heard quite a ruckus from while still at my house a little earlier that same afternoon. We decided that was probably when the attack occurred. We all felt sad for the herons, but we knew that what ever ate it (possibly an eagle) probably had young to feed, too. Living a block away from a heron rookery can be quite loud at times. As I learn more about them I can predict what may be occurring as I hear the varuous sounds from my backyard. Early in the breeding season I see herons landing in the fir trees near my house to pick out branches an twigs for nest building. When they fly in low it seems I can almost feel the wind move as they beat their huge wings. After a few weeks we start to hear a sound like ducks quacking and we know that the chicks are starting to hatch. When it sounds like a lot of ducks are talking all at once we think a parent must be approaching with food. As the weeks continue to pass the quacking sound becomes more prehistoric sounding. (I like to pretend I live in "Land of the Lost" with pteradactyls flying over regularly.) Every few days I hear all the herons start making noise at once. It can be quite loud and any time of the day or night. I now know that indicates a predator attacking. Luckily the population seems to grow inspite of the predators. About 5 years ago when we moved to this house there was only a couple of nests. Now the trees are full of them."