It's hard to get a sense of the size of these hawks from the camera feed. When you see them live, however, you realize how big they are. They are twice the size of a crow.
The formel (female) weighs generally in the range of 1250 to 1350 grams, which is between 44 and 48 ounces. The tiercel (male) probably weighs in the range of 1050 to 1150 grams, between 37 and 41 ounces.
The formel's length, head to tail, is usually about 18 to 20 inches. The tiercel is a bit smaller, from 16 to 18 inches or so.
Here are some pictures from last Sunday, kindness of Kay, from inside the Boardroom at the Franklin Institute. Although the trees look fall colored, it was indeed April!
This is the tiercel on the nest.
The following photos show his dark face and bib.
The tiercel left the nest which gave us a chance to closely inspect the eggs....
... before the formel flew in to resume incubation duties.
A close-up of her face clearly shows the pale bib under her beak.
When one is at eye or beak level with these hawks, it is really easy to tell them apart. The camera angle of the Ustream feed gives us a terrific view of what happening on the nest, but makes it a little tough to see their faces when they are sitting on the eggs.
In a couple of weeks, however, all being well when the eggs hatch, we will have ample opportunities to see the hawks together on the nest, as the tiercel brings food in, and we watch them feeding the newly hatched eyasses.