I hadn't previously noticed birds eating the beautyberry berries, but during the first ice storm this year...the cardinals made away with them.
Sandy, I don't know....(nandina's) but the website I'm editing now states Nandina berries are poisonous to birds...so I google'd and found this:
http://www.recordonline.com/apps/pbcs.dll/article?AID=/20130914/COMM/309140307/-1/NEWS14

The jury seems to be out on the toxicity to birds. The US Forest Service says not. Other sources say yes. It seems to be evenly balanced with differenct sources saying yea or nay. I think there needs to be some more research. The birds don't eat many of them here, anyway.I think the key may be the words "excessive consumption" as cedar waxwings will sometimes strip anything red as they come through and it may be a problem for them on occasion.

Here"s one response from the U of Washington Botanic Gardens:

Here is a link that might be useful: Nandina berries

It would seem the responsible and prudent thing to consider replacing Nandina and not planting any more.
I must confess I had two at my house in Oklahoma.

I love Nandina. They remind me of big ferns that stay all winter.

I read the berries fall and the "seeds" make new Nandinas. My biggest bed of them sure doesn't need to be increased, so I routinely snap the berry clusters off. I'm forever inviting friends to dig up the smaller ones . And they do, thankfully.

Sunny

I have never seen the birds eating on mine. Also mine have never set seeds...I have a large plant about two feet from the mother bush; I thought from roots but maybe it was actually a dropped seed.

Sandy I enjoy reading your articles.
I planted a long shrub row several years ago with wildlife in mind and several different shrubs that have berries. It's too far from a window to keep an eye on the birds that are feasting, but at least when you have shrubs instead of just trees, you get bird nests at eye level occasionally which is cool.
Hope nandina isn't toxic. I have that too. The birds seem to ignore it but I bet if we have a tough winter and they get hungry enough they would eat the berries. I have never noticed any volunteers from mine.