The 2024 shorebird nesting season began unlike any other, with the first island-wide sand placement project in Sanibel’s history. The project initially sought to fill in the large gullies and areas of standing water created by the massive storm surge of Hurricane Ian in September 2022, and also included the placement of sand and construction of a berm across much of the island.

“This sand placement seaward of the dune vegetation covered the natural sand, leading to drastic changes in the habitat for coastal wildlife, especially beach-nesting birds like the snowy plover (Anarhynchus nivosus),” said SCCF Shorebird Technician Aaron White.

The City of Sanibel deemed the project necessary after Hurricane Ian’s landfall flattened the island’s beach and dune areas. “As the storm surge from Ian receded, significant erosion occurred resulting in the creation of channeled gullies along Sanibel’s coastline,” according to the City’s website. 

Zero Snowy Plover Successes on Sanibel this Year

There were only two snowy plover nest attempts on Sanibel this year, both by a well-known banded individual White/Blue, nicknamed “super dad” for his consistent ability to successfully fledge chicks every year since his banding in 2019. Notably in 2023, he was able to successfully fledge a total of six chicks from his two broods, likely due to reduced disturbance on the beach, and increased foraging habitat in the gullies formed by Hurricane Ian.

“White/Blue’s first nest in 2024 was on the seaward side of the berm in an old wrack line, however it was exposed to repeated wash overs, and only one egg hatched. Unfortunately, the chick disappeared shortly after hatching,” White said. “After this failed nest attempt, he moved to Fort Myers Beach where he was able to hatch chicks, however they too disappeared shortly after hatching.”

White/Blue returned to Sanibel for a third and final nesting attempt in the natural sand on the dune side of the berm, with both the berm and dune vegetation blocking sight lines. Snowy plovers typically favor nesting in areas with open sight lines for easy detection of predators, White explained, and unfortunately, this nest was depredated by a coyote shortly after a hectic Fourth of July weekend.

The 2024 season marks the lowest number of snowy plover nest attempts on record, and the first time that zero chicks have fledged since SCCF began consistently monitoring in 2002.

Shorebird Impacts of Beach Renourishment

The effects of renourishment projects on snowy plovers and their habitats have been studied in the past.

• Research published in 2011, using data along the Florida Gulf Coast, found that it was 2.5 times more likely that a region was not a breeding ground (defined as 10 or more nesting sites) following a renourishment event (Convertino et al, 2011).
• Snowy plovers prefer beaches with natural debris and organic material that provides food and camouflage for themselves, their nests, and their chicks. Renourished beaches cover this natural habitat and as a result may negatively impact chick survival by reducing options to conceal themselves from predators (Pruner 2010).
• Prey availability is also impacted in that it tends to decline temporarily following renourishment (Dugan & Hubbard 2006; Peterson et al. 2006).

“Not only were the natural wrack lines covered by placed sand, but ephemeral pools created by Hurricane Ian were also filled in with new sand. Ephemeral pools positively impact chick survival, and nesting adults choose to nest near ephemeral pools because of their prey availability,” White said. “We observed this trend last season from our Sanibel snowy plovers with all three nests occurring near ephemeral pools, seven of nine chicks fledging, and six of seven in record time for chicks fledged on island.”

Decreased levels of human activity following the hurricane may have also played a role, he added.

Least Terns Fledge Young on Sanibel Causeway for First Time in 30+ Years

Least terns (Sternula antillarum) attempted to nest across multiple locations in our region this year.

For the second year in a row after a 30-year absence, least terns nested on the Sanibel Causeway. Since the causeway is an active construction site, SCCF, the Florida Fish & Wildlife Conservation Commission, and the Florida Department of Transportation worked collaboratively with the contractors to get this site monitored to ensure the safety of the birds.

According to the most recent data, least terns on the Causeway successfully fledged young for the first time in at least 30 years!

Off-island at Bunche Beach, least terns had a small colony that did surprisingly well considering its size. At least five chicks fledged from five total nests. On Sanibel, least terns attempted to nest twice but both attempts failed quickly as they were not able to grow the colony large enough to adequately defend their nests from predators.

Off-Island Shorebird Monitoring

At another off-island site, SCCF’s McGregor Preserve, various shorebird species nest, including killdeer (Charadrius vociferus), Wilson’s plovers (Anarhynchus wilsonia), and black-necked stilts (Himantopus mexicanus). 

“These three nesting species are very secretive and chicks are extremely well camouflaged in this habitat, so our team is very careful to minimize disturbance while monitoring,” White said. “While there was abundant nesting activity on the preserve, very few chicks, if any, survived to fledging after a massive rain event flooded the nesting areas.”

Wilson’s plovers were once again successful at Bunche Beach, where SCCF’s shorebird team collaborates with partners from the J.N. “Ding” Darling National Wildlife Refuge to monitor and protect beach-nesting birds.

At least six Wilson’s plovers chicks fledged before Tropical Storm Debby washed over the entire area. Wilson’s plovers have been absent from Sanibel Island since 2021.

“This season provided SCCF with valuable data about specific habitat requirements for nesting snowy plovers. Additionally, our team learned more about mudflat-nesting species after a full season of consistent monitoring at the McGregor Preserve,” White said. “Despite this season’s struggles, SCCF remains dedicated to the protection and preservation of all of the islands’ nesting and migratory bird species.”

Citations

• Convertino, M., Donoghue, J., Chu-Agor, M. et al. Anthropogenic Renourishment Feedback on Shorebirds: a Multispecies Bayesian Perspective. Nat Prec (2011). 
• Dugan, J. E., Hubbard, D. M., Marine Science Institute, & University of California. (2006). Ecological responses to coastal armoring on exposed sandy beaches. In Shore & Beach (Vols. 74–74, Issue 1, pp. 10–16).
• Peterson, C. H., Bishop, M. J., Johnson, G. A., D’Anna, L. M., & Manning, L. M. (2006). Exploiting beach filling as an unaffordable experiment: Benthic intertidal impacts propagating upwards to shorebirds. Journal of Experimental Marine Biology and Ecology, 338(2), 205–221.
• Pruner, R. A. (2010). CONSERVATION AND MANAGEMENT OF THE SNOWY PLOVER ALONG THE FLORIDA GULF COAST: HABITAT SELECTION AND THE CONSEQUENT REPRODUCTIVE PERFORMANCE. M.S. Thesis, University of Florida.