"You don't want to stand around too long without the risk of getting bombed," said Charles Pulcifer, a resident at the Empire Village Apartments.
The birds make gurgling sounds from atop the eucalyptus branches where they've built nests. And they aren't small -- the egret and heron stand 2 feet tall, on average.
Art Dunahoo, the apartments' maintenance man, has to hose down sidewalks below the nests.
"I hose it down. It comes off really easy, but the next morning it's right back again," he said.
Last year, there were only a few nests in one eucalyptus tree, but now there are about a dozen nests, and more in two other trees. The birds are protected, so the nests can't be bothered; even when chicks fall into the surrounding bushes, they have to be left alone.
The nesting season ends in about a month, and then the birds will fly off, taking their airborne bombs with them.
This article originally appeared on KCRA.com