Woodstork nesting success in 2020 in the Everglades region was down/Audubon Photography Awards, Lorraine Minns

Editor's note: Erika Zambello is the communications director for Audubon Florida, and a member of National Parks Traveler's board of directors. Audubon Florida staff contributed data and analysis to the report and Audubon’s summary.

How did nesting wading birds do in the greater Everglades region during the 2020 nesting season? According to a report released by the South Florida Water Management District, the season proved to be a mixed bag.

Each year, researchers from nonprofits, agencies, universities, and more work together to combine wading bird survey results from across the Everglades. Unsurprisingly, data collection efforts in 2020 had to be altered as a result of COVID-19 protocols. As a result, some data are incomplete compared to previous wading bird reports.

System-wide Nesting Numbers

Nesting numbers in 2020 were an order of magnitude higher than those seen in historically low nesting years in the 1980s and '90s. However, 2020 nesting still fell short of the historically high nest numbers of the 1930s and '40s. This suggests that restoration efforts since the 1990s have improved the foraging conditions that lead to increased nesting, but significant room for improvement remains as Everglades restoration continues.

Overall, Great Egret, Wood Stork, and White Ibis nesting has been increasing steadily since 1986, meeting restoration targets in most years since 2000, including 2020. Roseate Spoonbills also did well, while the early arrival of the rainy season spelled disaster for some populations of wading birds, especially Wood Storks in Southwest Florida.

"This latest reporting year is about an average year for nesting activity. This is expected to happen some years because of climatic conditions. Drier than average conditions for most of the nesting season followed by a large rain event in May created unfavorable conditions for nesting," said SFWMD Dr. Mark Cook, lead editor of the SFWMD Wading Bird Report. "In past years these conditions could have led to a very poor nesting year but this was average. Things have improved over the past decades because we are improving water management and building additional restoration projects.” 

A Closer Look at Everglades National Park

Numbers from Everglades National Park in particular looked promising. Twenty-five percent of nests were in coastal areas of the park - in the 1990s and 2000s, only 2-10 percent of all nests occurred in these habitats. This has improved in recent years, ranging from 15-41 percent. The restoration target is 50 percent.

Last year's nesting season marked only the sixth time in the past 20 years that wading birds made more than 10,000 nests in this region, continuing the positive trend seen in recent years. Despite high nesting effort, nesting success – defined by the number of fledged chicks – varied, based on the timing of nesting in relation to the high rainfall events in May.

Only three colonies had greater than 1,000 nests, and all three were in the coastal mangrove habitat, which may be in response to ongoing restoration activities inland. This area historically hosted the large supercolonies observed in the 1930s and '40s, but was largely abandoned from 1980 to 2000.

Birds of Concern

Wood Stork nesting has been trending upwards in the Everglades system in recent years, but 2020 nest numbers were 28 percent lower than the ten-year average. This demonstrates the vulnerability of South Florida Wood Stork colonies to variations in annual rainfall patterns and sporadic water levels. Unfortunately, as the impacts of climate change become more intense, these patterns could become the norm.

Researchers at Audubon’s Everglades Science Center are also documenting the difficulties faced by Roseate Spoonbills in Florida Bay. Nesting efforts of this iconic pink species in Florida Bay are still lagging, and the birds continue to initiate nesting more than a month later than they did historically. While Florida Bay is seeing hydrological benefits of Everglades restoration, sea level rise is counteracting these gains.

Spoonbill success in Florida Bay was moderate in 2020, with young fledged from 47 percent of nests. Audubon has found that low water levels at the time of hatching are the greatest determinant of spoonbill nest success. This data suggests that in order to best protect spoonbills, rising sea levels should continue to be incorporated into the planning and operation of Everglades restoration projects.

Why do we watch the wading bird numbers so carefully?

Super colonies of wading birds once nested in the Everglades. Hundreds of thousands of birds could form these giant groups; as just one example, the Wood Stork colony at Audubon’s Corkscrew Swamp Sanctuary alone was estimated at 100,000 birds.  Adapted to the historic water conditions in South Florida, the mind-boggling nesting seasons of these birds first faced decimation by humans during the hat-plume craze at the turn of the 20th century, and then by the massive draining and reshaping of the Everglades after World War II.

Today, the nesting success of wading birds as well as their overall population numbers are a critical barometer of Everglades ecosystem health, and the birds tell us if restoration efforts farther up in the watershed are successful.