Lying down on the grass at the edge of the pond with 1DmkIV and 500+1.4 or 2X extenders provides a great perspective on the grebes and their chicks, you just have to avoid the "landmines" left by the geese...
The primary diet of the adults is fish, and if they can catch it they will try to swallow it, although sometimes I have seen them give up after trying unsuccessfully for 10 minutes.
Most pairs have from one to three chicks, but third chick has low odds for survival. The gulls in the park have figured out that the chicks are easy pickings.. They have a much higher success rate when they have two chicks.
The young are fed insects, larvae, small fish and even feathers which supposedly line their stomachs to prevent damage from point fish parts.
The first couple of weeks the chicks spend most of their time hitchhiking on their parents back, which is the safest place to be with all the hungry gulls around.
After six weeks the young are pretty independent and the parents may even start on a second clutch of eggs if they began early enough in the spring. By September the grebes and their young have moved out to the open ocean and congregate in larger groups, without the fights over space and food they faced in the park.
Hopefully in a couple of months the first arrivals will be in place for a new season.