South Florida's wading bird population suffered during 2012, with nesting on the decline due to the return of too much water too fast for herons, Wood Storks, ibises and egrets.
The 2012 wading bird nest total was a 39 percent decline compared to the average over the past decade, according to the South Florida Water Management District.
While the 26,395 wading bird nests found were just 57 less than last year, it was also the third year in a row of poor nesting totals.
It continued the steep drop off from 2009's spike to 77,505 nests -- which was the most since the 1940s.
Back to back years of drought followed by a rainy 2012 resulted in yo-yoing water levels that caught many wading birds off guard. Also, the small prey fish that wading birds rely on to survive have yet to recover from previous droughts.
When the water is too high and prey fish aren't plentiful enough, wading birds either can't nest or they abandon their nests and leave the young to starve.
Manmade manipulations of water supplies from Lake Okeechobee to the Everglades add to the strain.
Draining more water into wetlands to keep farms and towns dry during storms and taking more water from wetlands for the public supply during droughts can throw off wading bid nesting.
"It really comes down to the water," said Terrie Bates, the district's director of water resources. "They literally live or die based on water levels."
In addition to wading bird nesting declining this year, the totals are far below targets for Everglades restoration.
In Everglades National Park and the Everglades water conservation areas that stretch across Broward and Palm Beach counties, the 346 Tricolored Heron nests found during 2012 were far from the 5,000 nests target set in the state and federal restoration plan.
The 820 Wood Stork nests were well under the 1,500 nests restoration target.
Decades of draining and development destroyed about half of the Everglades' wetlands. Wading bird populations have dropped about 90 percent from the flocks that once darkened the skies, according to Audubon of Florida.
Long-planned-but-slow-moving Everglades restoration seeks to counteract that human influence by storing and cleaning more stormwater so that it can be used to replenish Everglades wetlands instead of draining so much water out to sea for flood control. But that restoration requires building more water storage areas and pollution-filtering marshes, which remain behind schedule.
"We throw away water when it's abundant [and] then when a drought comes ... we make the drought doubly worse," Audubon scientist Paul Gray said. "The birds and the plants and the fish just can't keep up."
In 2012, the number of Snowy Egret nests dropped by 56 percent, Wood Storks nests declined 44 percent and White Ibis nests dipped 39 percent, compared to the average over the past decade, according to the water management district.
The decline in endangered Wood stork nests was particularly troubling because scientists also found that all 820 of the wading birds nests in the Everglades either failed or were abandoned, meaning no offspring survived.
This comes as federal wildlife officials this month announced that they are considering upgrading the Wood Stork's status from endangered to threatened due to rebounding populations across the Southeast.
"That's a serious issue," Drew Martin of the Sierra Club said about the Wood Stork nesting woes in South Florida. The water management district needs to make wading birds and other environmental needs a bigger priority when divvying up water supplies, according to Martin.
Wading birds typically nest during Florida's winter-to-spring dry season.
Part of the problem this year was that nesting started later than usual, which may have been due to more rain than usual during April and May, according to the district.
Also fewer eggs were laid per nest, about two to three eggs per nest this year compared to three to five, the district found.
The result of water levels at times being too high for birds to nest and prey not being plentiful enough at other times was that many nests failed to produce surviving offspring, according to the district's findings.
"They tried to nest, but there just wasn't enough food for them," Gray said. Wading birds, which can live more than 20 years, will abandon nests and their young when conditions aren't right, Gray said.
Roseate Spoonbill nesting totals did show signs of hope. While the numbers were below normal, the 348 nests were more than last year and were found in more areas than usual.
The long-term hope is that Everglades restoration makes water levels more consistent for wading birds, Gray said.
Next year is expected to be better for wading birds. While 2012's plentiful rainfall helped the dried out marshes recover, the bounce-back for small prey fish populations typically comes the following year.
"Most of the march [had] been dry for a very, very long time," Bates said.
abreid@tribune.com, 561-228-5504 or Twitter@abreidnew ___
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