IME, the berries persist until eaten. It's not uncommon for early returning birds like robins or cedar waxwings to descend and strip them entirely in one day. Not being eaten probably means that there are other foods sources that are preferred nearby.

Another thing to consider is that some berries must ferment before the birds can eat them. The Hawthorn here holds the fruit until they turn black and seem inedible. Then the birds devour them.

I don't think winterberries in general need fermenting since around here they usually get eaten by Christmas. However, I don't have experience with 'Red Sprite' in particular, and so there may be something in that selection that makes it unpalatable until later in the winter.

Are the berries larger on this cultivar than usual for the species? Seems I read somewhere that this is true and may play a role with their avian consumption. No idea for sure, though. Hey, I read it on the internet so it must be true! Right?

John

Most of the winterberry hollies here in Raleigh, NC still have loads of berries. I think the birds will descend on them as soon as they are sufficently ripe, which may not be until later in the winter. I have noticed the same thing with acorns. The bluejays wait until they are soft, then show up in numbers.
I, on the other hand, have zero berries on my Red Sprites. They were at our mountain house and the deer ate every leaf of both the Red Sprites and the Jim Dandy last summer. I transplanted them in October to our Raleigh house, which, so far, has no deer. (The deer are in the neighborhood, but don't yet come as far as our street.) Hoping for berries next year!