One of the nation’s largest and most important wading bird breeding areas—south Florida, which includes Everglades National Park—has seen wading bird nesting plummet 28 percent below 2013 levels and about 18 percent below the nine-year average for the area.
According to the South Florida Wading Bird Report from the South Florida Water Management District, an estimated 34,714 wading bird nests were initiated in south Florida during the 2014 nesting season (December 2013–July 2014), a significant drop from last year’s estimate of 48,291 nests and well below the average of the last nine years—42,782 nests.
This is the 20th edition of the wading bird report which provides a long-term, continuous record of annual nesting dynamics for south Florida and has proven essential for assessing and guiding restoration and management activities in the Everglades region.
Most wading bird species reduced nesting effort in 2014, but the extent of the decline varied.
Of particular note are the small herons, which have shown consistent declines in nest numbers in recent years. Nesting effort by Little Blue Herons, Tricolored Herons, and Snowy Egrets continued to decline, with nest numbers down 83 percent, 42 percent, and 47 percent, respectively, relative to last year, and down 91 percent, 53 percent, and 57 percent relative to the nine-year average.
These declines have been especially acute in the Everglades where numbers have steadily dropped from greater than a thousand nests per species for a typical year in the mid-2000s to only four Little Blue Heron, seven Tricolored Heron, and 122 Snowy Egret nests in 2014. Roseate Spoonbills also exhibited reduced nesting effort in 2014. In Florida Bay, Roseate Spoonbills nesting effort (126 nests) was less than half that of recent years (e.g., 367 nests in 2013) and a third of the 30-year average (479 nests). In the central Everglades, Roseate Spoonbills nesting fell from over 200 nests per year during the last three years to only 50 nests in 2014. Great Egret and White Ibis nesting effort was also reduced, but to a lesser extent than other species, down only six percent and 10 percent, respectively, from the nine-year average.
“An environmentally healthy Everglades Region is vitally important to many thousands of wading birds. Clearly, the significant declines in nesting of many of the typical species of the region tells us that much remains to be done to make it a properly functioning ecosystem,” said Kacy Ray, who directs American Bird Conservancy’s Beach Nesting Birds Program.
The only species that did not experience reduced nesting in 2014 was the Wood Stork, which produced 2,799 nests, a 26 percent improvement over the nine-year average. The report suggests that wetter than normal conditions in 2013 led to higher water levels in large areas and was conducive to greater fish production which are a key source of food for storks.
Most wading bird nesting in south Florida occurs in the Greater Everglades. During 2014, those wading birds initiated an estimated 25,529 nests (74 percent of all nests in south Florida) in the water conservation areas and Everglades National Park. This nesting effort is 28 percent lower than last year (35,580 nests) and the decadal average (35,483 nests). Lake Okeechobee, another important nesting area, produced an estimated 3,457 nests (about 10 percent of all nests in south Florida). This is fewer than half the 8,461 nests that were initiated on the lake last year and is down 32 percent relative to the nine-year average. In contrast to these declines, nesting Wood Stork returned to Corkscrew Swamp Sanctuary and produced 270 nests. Wood Stork have historically nested there in relatively large numbers, yet had not done so in six of the last seven years.
The data reveal that several nesting responses used as indicators of area restoration success have improved over the past 20 years, while others have not changed or are getting worse. For example, nest numbers of ibises, storks, and Great Egrets have increased over the past 15 years and are regularly meeting restoration targets.
The report says that the improvement in some nesting responses suggests that conditions in the Everglades have become more favorable to birds, possibly as a result of a combination of altered water management regimes, decadal shifts in climate and annual patterns of inundation within wetlands, and a reduction in mercury levels. On the other hand, the decline and stasis of other responses show that current conditions are not comparable with those prior to drainage, and in many respects are getting worse.
Ecological deterioration is occurring across all parts of the ecosystem, the report concludes, and this increases the probability of irreversible ecosystem changes that limit the possibility of recovering the essential defining characteristics of the historical Everglades. Nesting targets might become unattainable, the authors say, if ecological conditions continue to degrade and the status quo is not improved upon soon.