Updated: January 30, 2014 at 4:48 pm
MIAMI (AP) — The nesting of wading birds, a key indicator of the health of Florida's Everglades, has made modest gains, according to an annual report released Thursday.
According to the report issued by the South Florida Water Management District, wood stork, white ibis and great egret nesting significantly improved in 2013. The number of roseate spoonbill nests in Florida Bay also increased, though scientists caution that the total is still far below the historical average.
Other wading bird species that have shown steep declines in nesting in recent years did not show any improvement last year, however. Snowy egrets and tricolored and blue herons had significant declines, in particular.
Overall, last year was a relatively average year with 48,291 nests, officials said,
The best year on record for nesting since the 1940s was 2009, when officials counted 87,564 nests.
A primary goal of Everglades restoration efforts is improving natural water flows to sustain healthy wading-bird populations. Historically, large flocks of birds thrived throughout the Everglades, but their populations declined as canals and flood-control structures drained the wetlands for South Florida's development.
Most Everglades restoration projects remain delayed by funding and legal challenges. "What we're using these numbers for is as a marker for what we expect to improve in the future," said Mark Cook, lead scientist for the district's Everglades systems assessment section.
One major restoration project that started operations last year is exceeding expectations in improving wildlife habitat, which could lead to bigger increases for some wading bird nesting within the next few years, according to Audubon Florida.
The C-111 Spreader Canal was designed to plug an existing canal and keep water from seeping out of Everglades National Park. Since it came online, water has been redirected through the park into Florida Bay, where salinity levels are dropping and underwater plant communities are thriving, Audubon officials say.
"The health and quality of habitat in Florida Bay is improving — habitat that roseate spoonbills, game fish and crocodiles depend on," said Jerry Lorenz, Audubon's state director of research. "I'm hopeful that as new restoration projects come on line we will see wading birds returning in larger numbers to their historic nesting grounds in the Everglades."
Conditions were right last year for a good nesting season, Cook said. The rainy season was very wet, which was good for the fish populations that the birds eat, and the water levels fell when the birds began to nest early in the dry season.
Everglades National Park and Lake Okeechobee were more attractive to wading birds for nesting last year, but wood storks failed again to breed in Corkscrew Swamp Sanctuary, the report said. The sanctuary in Collier County was once the largest wood stork nesting site in all of North America, but the birds have not nested there for six of the past seven years.
This year, however, sanctuary officials say wood storks are returning to nesting sites they had abandoned years ago.
Cook cautioned that any gains could be undone over the next year if heavy rain events disrupt conditions where the birds are nesting now.