“Our task must be to free ourselves… by widening our circle of compassion to embrace all living creatures and the whole of nature and its beauty”. -Albert Einstein
The Wood Stork, Mycteria americana, is the largest wading bird and the only stork, out of 19 species worldwide, that breeds and lives in the United States.
This very conspicuous bird is broadly distributed from the southeast of the United States (South Carolina, Georgia, Florida) south to Mexico, Central America, and all South America; it received its taxonomic classification in 1785 in Brazil.
It wasn’t until last year (May 2019), when I began visiting many of the South Florida wetlands, that I had my second encounter with this curious stork, and what an encounter it was! I had read a lot about Wakodahatchee Wetlands, an artificial preserve constructed on 50 acres of previous wastewater, operated by the Palm Beach County Water Utilities Department. People raved about the place, and its wildlife, so I checked it out.
As soon as I entered the preserve, a majestic wood stork greeted me. It was standing in a branch in one of the many cypress trees that are part of those wetlands. But that was just a tiny taste of what was yet to come. I did not have to walk over 20 feet to discover hundreds of Wood Storks in almost every tree. Most of them paired in couples taking care of their hatchlings. It was an incredible and fascinating experience.
After that photo safari, I began learning more about wading birds and the wood stork colonies in South Florida. It turns out that what I witnessed is part of a revival of this species in the region.
The wood stork is an endangered species in Florida. Although it is nowhere near the historical population that foraged and nested in the Everglades and surrounding areas, it is making a slow comeback mirroring the efforts to restore the iconic River of Grass, as Marjory Stoneman Douglas used to call what is now Everglades National Park.
The breeding population of wood storks in the southeastern U.S. declined from about 15,000-20,000 pairs in the 1930s to a low of 4,500-5,700 pairs from 1977 to 1980. The lowest annual estimate occurred in 1978 when only 2,500 pairs of wood storks got together to breed.
So what happened? Well humans happened. what else?
It turns out that food availability throughout the entire breeding cycle is critical because nesting is strongly affected by caloric intake. In the wood stork’s case, its breeding cycle is carefully synchronized with the cycle of the wetlands to ensure that the maximum food supply occurs while the young are being raised. To nest successfully, the wood stork must time its reproductive cycle so that the highest fish densities happen when the food needs of the growing young are at their maximum. Also, the young must be fledged and on their own before the summer rains begin and disperse the fish. Widespread nesting failures can result from natural causes like droughts in the wet season, or heavy rains during the dry season, or human drivers like habitat disruption and inappropriate manipulation of water levels.
In the last century and a half, Florida lost most of its natural wetlands. People moving to the state saw them as a significant obstacle to settlement. Many were drained and their vegetation removed to accommodate housing developments, parking lots, highways, and many other types of construction. The Everglades that used to occupy most of South Florida was reduced to a third of its original size. What remains is what we know today as Everglades National Park.
Since everything in nature is interconnected, the significant reduction of these vital ecosystems because of alterations to the natural hydrological system in the region has resulted in several critical changes to wading bird habitats.
The wood stork is what we call a tactile feeder, and it forages by moving its open bill vertically or from side to side in the water until it touches prey. Then it uses an exceedingly rapid bill-snap reflex to capture prey, a technique that requires no sighting of the prey item (Ogden et al. 1976:324). A non-visual method of feeding is an advantage in a shallow, turbid, weed-choked marsh. However, prey must be concentrated for this method to be effective enough to provide sufficient food, especially during the breeding season. And the largest concentration of prey takes place during the dry season.
Researchers have established that the primary reason for the decline of the wood stork population in Florida is not excessive mortality but an inability to reproduce as they used to. Reproductive rates fell to almost catastrophic levels because of the lack of food resources caused by the mismanagement and the drainage of wetlands.
Things are improving for these peculiar birds
In 1984, the U.S. Population of wood storks was listed as endangered because it had declined by over 75 percent since the 1930s. The original listing recognized the relationship between the declining wood stork population, the loss of suitable foraging habitat, and colony nesting failures in the breeding colonies in South Florida, where human actions have reduced wetland areas by about 35 percent (Ogden and Nesbitt 1979). Because of this, the wood stork became a top management priority by government agencies throughout the southeastern U.S. And Florida, in particular.
In the year 2000, Florida and the federal government launched The Comprehensive Everglades Restoration Plan (CERP). A multibillion-dollar project designed to reestablish, where possible, the natural hydrologic characteristics of the Everglades and try to restore the disrupted ecosystems of the region. As part of this effort, a group of researchers developed a series of indicators to assess and communicate the success of the restoration efforts. The Science Coordination Group chose 11 ecological indicators relating to water quality, hydrology, and flood control.
One of those indicators is the breeding status of the wading birds in Florida. They chose the wood stork and the white ibis as critical biological indicators because of their unique feeding-habitat requirements that make them sensitive to water levels and changes in their prey populations. (Crozier & Gawlik 2003; Frederick et al. 2009)
In 2018, according to the May 2019 South Florida Wading Report, while all species exhibited increased nesting effort in 2018 relative to the 10-year annual average, some of the most significant increases were for the tactile foraging species, the white ibis, the wood stork, and the roseate spoonbill. The wood stork produced 5,777 nests, which is 2.4 times the 10-year average (2,448.1 nests) and the third-highest count since the late 1960s. This was also the second consecutive year of solid nesting effort for this species (3,984 nests in 2017). I guess there is hope for this peculiar funny-looking bird.
Wood storks bill-snap is one the fastest reflex actions among vertebrates (Kahl and Peacock 1963).
You can find more information about the wood stork in the Audubon Guide of North America Birds and the All About Birds section of of the Cornell Lab of Ornithology Website
2 responses to “The return of the wood stork to South Florida”
This is a great article. In 2009, I contacted the person responsible for the South Florida Wading Bird Report to inquire why Wakodahatchee Wetlands were not included in the report and it was because there were fewer than 300 nests. It’s nice to see Wakodahatchee now mentioned in the report.
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