As cold air blasted through the open window of the Cessna 172 Tuesday, Jason Lauritsen photographed seemingly insignificant white spots in Corkscrew Swamp Sanctuary’s bald cypress forest 1,000 feet below.

The spots were wood storks; they’re significant because the endangered species is nesting for the first time in three years at Corkscrew, the largest wood stork breeding colony in North America.                                 

Stork nests in Corkscrew are good news, said Lauritsen, a sanctuary resource manager.

“Some nesting colonies pop up and blink out, disappear after a few years, and some, like Corkscrew, go on for decades,” Lauritsen said. “It’s not out of the realm of possibility that the Corkscrew colony could blink out if we go several years in a row without any nesting.

“After two years without nests, we’re breathing a sigh of relief, and maybe a good nesting year will recalibrate Corkscrew as a hot shot in the stork’s dim reptilian brain.”

Storks started nesting in the northernmost point of the sanctuary’s bald cypress forest Dec. 12 — the nests cannot be seen from the boardwalk.

Two days later, Lauritsen counted 16 nests during an aerial survey; on Tuesday, the count was up to 19.

“I’m disappointed that there aren’t more nests after a week,” Lauritsen said. “I was hoping we’d have 30 or so.

“If the fish hold out, I think we’ll have a good season.”

Fish are key: The wood stork’s diet is mostly fish, and no fish in area wetlands means the birds won’t nest.

And the key to wetland fish populations is hydrology: How much water is in the wetlands and when it’s there.

For everything to work right, rains in the summer fill the wetlands, allowing fish to reproduce in huge numbers.

After the rainy season, the wetlands “dry down,” so fish become concentrated in shallow pools, which makes them easy to catch; easy prey is important because each chick requires about 440 pounds of food while in the nest.

When not enough rain falls during the summer, fish reproduction is too low to support a breeding colony, so the birds don’t nest at all — since 1958, dry conditions have kept wood storks from building nests at Corkscrew eight times, including the last two years.

With heavy rains returning to Southwest Florida this summer, area wetlands filled up and are now drying down to concentrate fish.

Typically, wood storks don’t start nesting at Corkscrew until after the first of the year; this is only the second time in 15 years nesting has started in December — the last time was 2002, when 1,240 nesting pairs produced 3,162 fledglings, the highest number since 4,100 storks fledged in 1976.

“We’re hoping that early nesting in Corkscrew is an indication of a good year, but it’s too early to know for certain,” said Chuck Underwood, spokesman for the U.S. Fish and Wildlife Service. “The early nesting in Corkscrew and with all the rain we’ve gotten, we’re hoping to hear the same thing in Everglades National Park.”

Florida is the wood stork’s primary breeding location, but the drought has prompted some storks to breed in Georgia and South Carolina.

“They’ve adapted to the drought and moved north, which is a good thing,” he said. “But it’s good to see them in their traditional nesting areas in South Florida.”
Although conditions indicate a successful wood stork nesting season, Lauritsen said the drought might have a lingering effect.

“Coming off two years of drought, some of the fish populations haven’t recovered,” he said. “So I don’t know if the fish will come back enough to support the storks.
“One species, the marsh killifish, has a fast life cycle and might be able to make up for the lack of other fish. It’s a nice, big fish, 3 to 4 inches, round and meaty, and it’s one of the fishes storks target.”

Tuesday’s flight also checked out Lenore Island in the Caloosahatchee River just upstream from the Edison Bridge, where wood storks sometime nest; none was present.

“I’m not surprised there’s nothing at Lenore yet,” Lauritsen said. “Without getting into the storks’ heads, I think they’re looking for the best place first.

“Why do they prefer Corkscrew? Their little stork brains are processing that it’s the access to high-quality freshwater wetlands. If things go well at Corkscrew, it will spill over to other nesting areas.”

In addition to counting wood stork nests Tuesday, Lauritsen continued a project to determine where wood storks eat before and during nesting season.

So far, the study has shown storks tend to forage in artificial habitats such as golf course ponds and edges of canals early in the season.

On each flight, pilot Shawn Homoky of Beaver Aviation circles the nesting colony and follows any stork that leaves it.

On Tuesday, he followed a stork that spent 27 minutes flying about two miles before settling in a tree.

“Once they have chicks in the nest, I don’t think they’ll be lollygagging like that,” Lauritsen said. “The food demand is smaller until the chicks hatch. That’s when you should see them differentiate between OK foraging habitat and high-quality habitat: More meat and potatoes, less McDonald’s.”

Wood stork facts

Scientific name: Mycteria americana

Other common names: Flinthead, ironhead, wood ibis

Status: Endangered

Range: They nest from coastal South Carolina, southeast Georgia, Florida, Mexico, Central and South America to northern Argentina.
Habitat: Tidal waters, marshes, streams, mangroves

Size: 3.3 feet tall with a wingspan of 5 feet

Description: Black bill, scaly-looking featherless head, white plumage except for short black tail and black feathers bordering the wing.

By Kevin Lollar • klollar@news-press.com • December 26, 2008