The white ibis are gone, again, from the Citadel Mall pond where the hordes of them perching for the night has amazed neighbors, shoppers and visitors for more than a decade.

"It was so strange" to see the branches empty on a recent trip, said Jenny Turner, of West Ashley, who has made a point of taking visitors to watch the birds swoop in flocks to the trees in the evening. "It was so disappointing because it was such a beautiful place."

But bird specialists say it's likely nothing to be too alarmed about and the birds might return - again.

"Colonial" wading birds like ibis, egrets or heron that also roosted at the pond are nomads, specialists say. They tend to keep different summer roosts, or breeding roosts, from winter roosts. And some of the birds mini-migrate season to season, between the coast and inland, farther south to farther north.

They do like to get together at night at regular waterside roosts, where they pack the trees often in the hundreds. And they do tend to return to the same roost - unless it gets too cold or warm, or drought drains the pond or depletes their food or predators like raccoon show up. Disturbances also can spook them.

Impromptu roosts can be found above ponds all along the Lowcountry coast, and wherever they are found, people flock to watch. The roosts have become important refuges for wading bird species such as white ibis, egrets and heron. The species are considered to be in long-term decline partly because the natural roost habitats are disappearing as coastal areas like Charleston develop.

Great egrets are the slender white birds with orange beaks sweeping the skies or poised elegantly erect to spear fish in marshes across the Lowcountry. White ibises are a stork-like wading bird with a distinctive hooked orange beak and black-tipped wings. They glide with their wings gracefully curled.

They can roost by the thousands in trees surrounded by water or hanging over water, to discourage raccoons and other predators. They once roosted en masse on Drum Island beneath the old Cooper River bridges. When raccoons moved in, they moved away.

For decades at the pond tucked between Interstate 526 and the Citadel Mall Stadium 16 movie theater, the evening roosting display thrilled moviegoers, passersby and nearby residents. The birds would swoop in at dusk in rafts, flock after flock until "it looked like big flakes of snow," Turner said.

Then, in 2005, most of the birds spooked, apparently when the pond became part of a construction zone to provide more drainage for a nearby sporting goods store. But gradually they came back in numbers. For a while great egrets were the primary perchers.

There are a number of reasons why it might not be currently used, including a seasonally fluctuating availability of food in the pond, said wildlife biologist Christy Hand, with the S.C. Department of Natural Resources, and Nathan Dias, Cape Romain Bird Observatory director.

"It doesn't surprise me" the birds spooked again, Dias said. "They're not nearly as protected as they were." But it wouldn't surprise him, either, if the move turned out to be temporary.

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