 A pair of Swallow-tailed Kites. Photo by FWC.
It wasn’t long ago that Swallow-tailed Kites were in trouble. In the late 19th and early 20th century their populations had declined significantly. Today their numbers are rebounding, but they are still considered a species of conservation concern in the southeastern United States. FWC researchers recently located 132 Swallow-tailed Kite nests in and around the Corkscrew Regional Ecosystem Watershed WEA in southwest Florida. They monitored these nests to determine how characteristics of the nesting site affected the nest survival rate (the percentage of nests that survive to fledging).
Of these nests, 49 percent successfully fledged young. Researchers identified two key characteristics correlated with nest survival: nesting date and tree diameter. Nests started early in the nesting season (mid-March) were more than three times as likely to fledge young as nests started later in the season (mid-May). Additionally, nests in larger-diameter trees were more likely to be successful than nests in younger, smaller-diameter trees. These findings suggest that the large pine and cypress trees formerly found in old growth bottomland hardwood and lowland pine forests in the U.S. could have provided superior nesting opportunities for the kites.
Information for this article was provided by Karl Miller, Avian Research Scientist at the Florida Fish and Wildlife Conservation Commission.
 Least Tern adult feeding a chick. Notice the Least Tern adults incubating nests and the chicks shading underneath chick shelters. Photo by FWC.
Cameron Pressey, Rooftop Nesting Biologist at the Florida Fish and Wildlife Conservation Commission, answers some questions about this phenomenon for the Great Florida Birding and Wildlife Trail.
Which shorebirds nest on rooftops and why?
The primary shorebird species we monitor on rooftops are Least Terns, Black Skimmers and American Oystercatchers. All three of these species are state-threatened, but Killdeer, Roseate Terns and Gull-billed Terns will occasionally nest on rooftops as well. Roseate Terns are federally listed as endangered.
These are all shorebirds and seabirds that evolved to nest on beaches. There are a few reasons they are nesting on rooftops, including loss of beach habitat due to coastal development, rising sea levels and beach erosion, and pressures from the large number of people, vehicles and predators such as dogs on Florida’s beaches. Tar-and-gravel rooftops replicate sandy beach habitat and may offer the benefit of fewer people and fewer non-avian predators.
Why is it important to monitor rooftop nesting birds?
Rooftops are important nesting habitat for Florida’s threatened shorebirds and seabirds since nearly 50% of Least Terns, over a dozen American Oystercatcher pairs, and less than 1% of Black Skimmers are known to nest on rooftops in the state. Shorebirds have been recorded on rooftops in Florida since the 1950s, and FWC and Audubon Florida have been monitoring rooftop nesting birds for more than 20 years to maintain these populations.
The Florida Shorebird Alliance (FSA) is a statewide partnership of government and non-government organizations committed to advancing shorebird and seabird conservation in Florida. The FSA is integral to rooftop monitoring, and includes FWC and Audubon Florida staff and volunteers. You can get involved, learn more, and access resources at flshorebirdalliance.org.
What threats do rooftop nesting shorebirds face?
One main threat is the loss of the rooftops. Tar-and-gravel rooftops are being phased out, so we're losing viable rooftop habitat every year. Another major threat is human disturbance. Many folks simply don’t know these birds nest on rooftops, and that eggs or chicks can be injured from rooftop access. There are also predators, mainly Fish Crows and Laughing Gulls as well as Loggerhead Shrikes, Great-Horned Owls and other raptors, and rats.
Is there anything people can do to make their tar-and-gravel rooftops more friendly to nesting shorebirds?
Folks should coordinate with the Florida Shorebird Alliance to manage rooftops during non-nesting season, which is between September 1 and April 1. Conservation measures include completing routine rooftop and HVAC maintenance and repairs, installing chick fencing to prevent chicks from falling off rooftop edges or down drains and gutters, removing potential perches for avian predators, monitoring for fallen chicks and safely returning chicks to rooftops.
People should contact FWC if they need to access their rooftops during nesting season from April 1 until September 1. The reason for this is it’s important for folks to apply for an Incidental Take Permit when rooftop actions may result in “incidental take,” meaning any harm or harassment of rooftop-nesting birds during otherwise legal activities. Starting in 2024, there will be a course available to become a Qualified Rooftop Monitor at MyFWC.com. Qualified Rooftop Monitors will be able to assist rooftop activities and avoid take.
To learn more, you can review the Imperiled Beach Nesting Birds Conservation Measures and Permitting Guidelines.
What is the success rate of rooftop nests compared to beach nests?
That's a good question! The FWC’s Fish and Wildlife Research Institute (FWRI) staff are working on a productivity study to assess this, so we'll have more answers soon. What we know so far is that Least Tern productivity rates vary widely on rooftops, and rooftop productivity is comparable to that of beach nesting pairs.
Do the birds exhibit site fidelity?
Rooftop-nesting species often return to rooftops where they nested or hatched in previous years. However, we’ve also observed birds moving to new sites if the old rooftop is no longer viable or if the birds are losing a lot of eggs or chicks. Rooftops become unviable when tar-and-gravel is replaced, making the substrate not suitable for nesting. Also, when birds lose their young to predation or disturbance they may hesitate to return and try again. Interestingly, we’ve documented some young hatched from rooftops nesting at beach sites in future seasons, indicating that they aren’t always tied to the site where they hatched.
Is there anything that you would like people to know about the shorebirds or this project?
Many folks are unaware that threatened shorebirds nest on rooftops, and when they learn about birds on their building they may be concerned. These species are here for a relatively short amount of time to raise their young, and they don’t damage rooftops. Birds want to successfully fledge their chicks and return to the beach as soon as possible.
FWC and our partners are here to assist you and the birds through a successful nesting season. If you're interested in helping FWC survey rooftop colonies, contact your local FSA partnership for volunteer opportunities. You can reach us at Shorebird@MyFWC.com and access rooftop resources here. Thank you for helping future generations of birds and people!
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