Last Year’s Everglades Breeding Bonanza Was the Biggest in More Than 80 Years

A year ago, Everglades scientists and environmentalists were ecstatic about what looked like a blockbuster breeding season for South Florida’s wading birds. Turns out, it was far better than those early estimates indicated. New data show that the region hosted its biggest colonies of waders in more than 80 years, offering a flashback to the historical Everglades and a glimpse of how the ecosystem again could look once restored.

All told, wading birds built 138,834 nests throughout South Florida, with 122,571 of them in the Everglades, according to an annual report released last week by the South Florida Water Management District. That’s about three and a half times the average for the past 10 years, making it the strongest nesting season since before the region’s hydrology was transformed with engineering projects that made development possible but also contributed to steep declines in wading bird numbers.

When Audubon spoke last spring with Mark Cook, an avian ecologist and lead author of the report, he estimated from helicopter surveys that one massive colony contained around 18,000 White Ibis nests. But after a thorough count using drone photography, Cook now says the birds built more than 56,000 nests at that site alone, making it by far the region’s largest wading bird colony since the 1930s. There were more than 100,000 White Ibis nests throughout South Florida, more than five times the average count over the past 10 years. “That’s unbelievable,” Cook says. “They’re kind of off the charts.”

White Ibises were by far the most numerous wading birds last year, but Great Egrets, Roseate Spoonbills, and Wood Storks also flourished, with each species building more than twice its 10-year average number of nests during the nesting period that ran from December 2017 to July of 2018.

Because their nesting success is tied closely to the way water moves through the Everglades, scientists look to wading birds as indicators of the ecosystem’s health and the impact of the massive effort to restore its historic hydrology. Last year’s breeding explosion doesn’t mean all is well with the system, however. It was basically a fluke: An extremely rainy 2017 filled wetlands and fueled production of small fish and crayfish. Then, a dry period gradually drew down the water level, stranding fish in crowded pools, where they offered a smorgasbord for waders and their nestlings. Those lucky conditions mimicked pre-settlement Everglades hydrology, and offered a glimpse of what restoring that historic water flow could yield.

The report provides “a bit of hope for those of us who have read those historical accounts of clouds of wading birds in the Everglades so big that they blocked out the sun,” says Julie Wraithmell, executive director of Audubon Florida, which provides some of the data used in the report. “Having never seen it, you start to think, maybe it’s apocryphal. Maybe it’s like my dad with his fishing stories. But last summer’s supercolonies proved that it was not an exaggeration."

Not all of the numbers in the report are encouraging, however. Little Blue Heron nesting was in line with average numbers over the past decade, but in this case, average is cause for concern. Those birds and other small herons—including Snowy Egrets and Tricolored Herons, which each showed moderate improvements over the 10-year average—“have been declining like crazy over the past 10 or 15 years,” Cook says. “We’re not entirely sure why.” 

The good news also wasn’t uniform across the region. While the federally threatened Wood Stork had a banner year overall, the colony in Audubon’s Corkscrew Swamp Sanctuary remained relatively small at 328 nests. It could be much worse; in 8 of the past 10 years, there have been no stork nests there at all. And unlike many recent years in which they've begun nesting in February—which is dangerously late, since prey fish become unavailable by the time their chicks fledge—the birds last year built their nests in early December, in keeping with their historical patterns. Still, last year’s colony was nothing compared to the 7,000 nests built there annually in the 1960s. Wraithmell says that drainage canals and significant consumption for drinking water and agriculture dried up the state’s southwest corner, where Corkscrew is located, more quickly than the central and southern Everglades, where the breeding bonanza was biggest.

Unfortunately, despite the phenomenal success of last year, 2019 productivity is already shaping up to be a letdown, Cook says. Last year’s rainy season wasn’t as severe as in 2017, so wetlands didn’t get a strong recharge of water and prey. Then, heavy rains arrived this past January, when in an ideal breeding year the wetlands would be slowly drawing down. Still, even the undisturbed Everglades had good years and bad years, and last year’s explosion showed that extremely good years can still happen when water conditions are right.

That proof of South Florida's potential to support supercolonies has Wraithmell hopeful about the future for wading birds and the ecosystem they represent. Ron DeSantis, the state’s new Republican governor, has made environmental protection a priority, with a focus on accelerating Everglades restoration. And earlier this month, President Donald Trump updated his 2020 budget plan and called on Congress to provide $200 million for Everglades restoration, after initially proposing $63 million. Those funds would support projects that increase the flow of water south through the system and replenish the wetlands that waders need. If these long-legged birds herald what the Everglades once were and can be again, it seems their message is beginning to hit home.