For several months each year, just after dawn when zoologist Sue Maher arrives at the Conservancy’s Disney Wilderness Preserve (DWP), she unlocks the preserve gate, heads down the mile-long road, surrounded by tall grasses, past sandhill cranes, gopher tortoises, and beneath swallow-tailed kites, to Lake Russell. There she retrieves a green canoe, and drags it down to the waters edge. After loading in her gear she makes her way across the lake, settling in on the clear water near the rookery. She’s close enough to hear the calls of the birds though not disturb them, and far enough away to see 50 to 60 feet up to the tops of the trees, where the birds prefer to stay.
Maher, with the assistance of two other volunteers, Shannon Livingston and Chris Barth, has just finished the four month 2017 Wood Stork monitoring program at DWP. The combination of the right depths of fresh water, preferred fish and prey nearby, and no development on the shoreline brings the birds here just about every year. A population of North America’s only native stork, the Wood Stork, spends several months annually along the shore of the lake in the preserve, among branches that make perfect nesting spots. Maher knows exactly when the adult storks will arrive, and when they will depart with their fledglings. She’s been monitoring this growing population for more than 10 years!
The Wood Stork (Mycteria americana) is a long-legged wading bird that can be 50 inches tall, with a wingspan of 60 to 65 inches. The preserve colony typically makes its initial appearance each February or March, migrating from Mexico or South America. Though this population isn’t being tracked, it is likely that the same birds return each year. (There are some monitored birds known to migrate to the same rookery in Jacksonville each year.).
Initially listed under the Endangered Species Act, the stork was reclassified as threatened in 2014. The bird is part of the U.S. Fish & Wildlife Service (FWS) species recovery effort to which Maher reports each year.
A wood stork chick with its parents at Disney Wilderness Preserve in Florida. © Bob Blanchard
The wood stork monitoring program at DWP begin in 1995. Before it became The Disney Wilderness Preserve, the land was primarily a cattle ranch although slated for development. That development would have meant an end to the stork’s wetland habitat and the destruction of significant habitat for endangered plants and wildlife. Working with the Conservancy, the state and others, The Walt Disney Company purchased the property during the expansion of Disney World as part of a wetlands mitigation plan. The property was transferred to the Conservancy in 1992, with funding for restoration and wildlife monitoring
Maher recalls coming out to DWP in 2002 as a turning point. “I did basic work, helping to track the birds, learning how to record the data correctly, and I was hooked. I felt like I was making a contribution.”
In 2006 she was called back to become part of the monitoring program. “I was asked to help out once a week. We identified and marked the trees with tags in preparation for the birds’ arrival, then counted trees with nests, counted adults, then chicks, and observed their behaviors. The birds were fascinating and I was all in.” By 2007, Maher was doing the monitoring on her own, with other volunteers, and now 10 years later, it’s all hers.
DWP provides the storks with all they need. For these birds, both nesting and foraging behavior are intricately tied to freshwater levels and seasonal timing. The storks select mangrove and cypress trees along water sometimes using what is left from last season’s nest, or building a new nest, preferably where the water levels are up to three feet high so that terrestrial predators like raccoons and snakes won’t be able to swim to get access to eggs. The birds begin to nest during the time of the highest water levels, just after hurricane season. Avian predators like osprey and sometimes eagles are nearby, but are not a concern.
A wood stork brings a fish back to the nest at Disney Wilderness Preserve in Florida. © Bob Blanchard
The higher waters needed for nesting are in contrast to the shallow waters needed for foraging. The storks have a specialized feeding regimen. They favor the shallow depths in which they can sweep their partly open beak back and forth to probe for and quickly trap fish. They don’t feed at the nesting area because it is too deep, but fly to shallow lakes or swampy wetlands where prey is concentrated. Storks are known to fly several miles from the nesting colony to forage. At DWP, the storks have a relatively short commute. There are ponds onsite at the preserve that were developed specifically to provide the shallow water habitat and fishing grounds needed by wood storks. Again, timing is a factor – the water levels in these ponds drop just in time for the wood storks to begin feeding their young – as the dry season begins.
“They somehow know whether water levels will be right where they will be foraging,” said Maher. “If not, they don’t begin to nest there.” A nesting pair of storks and their young require an estimated 443 pounds of fish for the season. There have been a few instances over the years at DWP of heavy rains early in the nesting season that brought water levels up too high for feeding and caused the birds to abandon their nests.
The birds stay at the preserve for three to four months. They settle in right away to build nests and get ready to lay eggs. About four weeks later, the eggs hatch. The storks don’t have the area all to themselves.
“Last year there were 30 to 40 nests. This year, there were a total of 106 nests, 92 nests successfully fledging chicks,” exclaimed Maher. “It’s one of the most productive years ever documented.”