In April 2009, dozens of cedar waxwings were found dead in a single yard in Thomas County, Georgia. Their stomachs were packed with one thing: small, red berries.
The birds had hemorrhaged into their lungs, tracheas, hearts and brains. It was cyanide poisoning.
A decade later the curator of the UNC Chapel Hill Herbarium found dead waxwings on campus, in sight of a large nandina planting. That's what finally prompted somebody to test the berries.
Nandina, sold as heavenly bamboo, is from China and Japan, it's invasive across the Southeast, and it's still sold at garden centers.
Most birds can detoxify small amounts of cyanide. Eat one or two nandina berries and you'll be sick for a day. Cedar waxwings don't eat one or two. They gorge on them. A flock strips a bush in minutes.
And the ripe berries release cyanide slowly as they digest. There's no warning, no bad taste, nothing that says stop. By the time it's hitting, the bird has a crop full of them.
Worse, nandina berries hang on all winter, when almost nothing else is fruiting. It's most attractive exactly when the birds have the fewest options.
If you have one, cut the berry clusters off before they ripen. That solves the problem this year.
Then dig it out. Get under the root crown and pry it up, or it comes back. Alternatively, a cut stump with a dab of herbicide will usually kill it for good.
Replace it with winterberry holly, American holly, or eastern red cedar. Red berries all winter, and waxwings are supposed to eat those.