Index Nesting Beach Survey Totals (1989-2018)
Since 1989, the Fish and Wildlife Research Institute (FWRI) has coordinated the Index Nesting Beach Survey, a detailed sea turtle nesting-trend monitoring program conducted in conjunction with the Statewide Nesting Beach Survey. The index survey uses a standardized data-collection protocol to measure seasonal nesting and allow accurate comparisons between beaches and between years. Consistent effort by location, fixed dates, and specialized annual training of beach surveyors make the index program suited to these trend assessments. Approximately 30 percent of Florida's beach length is surveyed following the index-survey protocol.
FWRI coordinates data collection through a network of surveyors, including federal, state and local park personnel; other government agency personnel; members of conservation organizations; university researchers; and private citizens. FWRI staff provide annual training to beach surveyors and compile data from the annual surveys.
At a core set of index beaches monitored since 1989, trained surveyors monitor 329 kilometers of nesting beach (204 miles) divided into zones that average 0.8 kilometers (approximately a half mile) in length. These core index beaches represent the Atlantic and Gulf coasts of peninsular Florida. Beach surveyors monitor core index zones daily during a 109-day sea turtle index-nesting season (May 15 through August 31). Surveyors record nests and nesting attempts by species, nest location and date. Index nest counts represent approximately 54 percent of known loggerhead nesting in Florida, 69 percent of known green turtle nesting and 34 percent of known leatherback nesting.
A loggerhead sea turtle nesting throws sand over a nest, concealing her eggs, on an index beach in Brevard County.
Photo credit FWC/FWRI taken with infrared camera to reduce disturbance to wildlife.
Observed loggerhead nest counts on Florida’s 27 core index beaches have varied greatly since the beginning of the program in 1989, reaching a minimum of 28,876 in 2007 and a maximum of 65,807 nests in 2016. These numbers DO NOT represent Florida’s total annual nest counts because they are collected only on a subset of Florida’s beaches (27 out of 224 beaches) and only during a 109-day time window (15 May – 31 August). The standardized data collection approach used by the INBS program is designed to examine nesting trends. Nest counts on Florida’s 27 core index beaches reveal a complex nesting pattern for the loggerhead turtle with three distinct phases. Researchers do not yet understand fully what drives fluctuations in annual nest count. The observed pattern may even be part of a long-term cycle but many more years of standardized nest counts are needed to assess this hypothesis.
Below: Annual loggerhead nest counts on core index beaches. Survey effort remained nearly identical. These data represent peninsular Florida and exclude an additional set of beaches in the Florida Panhandle and southwest coast that were added to the program in 1997 and in more recent years.
Index beaches in the Florida Panhandle, which are not part of the set of core beaches, had lower loggerhead nest counts in 2018 compared to the two previous years but nest counts were similar to 2015. This count does not include three additional beaches that joined the INBS program in the Panhandle in 2016: St. George Island State Park, St. Joseph Peninsula and Gulf Island National Seashore.
Concern over declines in annual loggerhead nest counts (observed between 1999 and 2007) prompted researchers to conduct a detailed analysis of the species’ nesting trends since 1989. Download a 2009 journal article about the research:
Decreasing Annual Nest Counts in a Globally Important Loggerhead Sea Turtle Population.
The article Trends in Nesting by Florida Loggerheads includes survey data through 2018.
Green Turtle Nests
Green turtle nest counts have increased eightyfold since counts began in 1989 – a trend that differs dramatically from that of the loggerheads that nest on the same beaches. In 2018, green turtle nest counts on the 27 core index beaches were dramatically lower than in 2017 (the record high year since the beginning of the INBS program). These numbers DO NOT represent Florida’s total annual nest counts because they are collected only on a subset of Florida’s beaches (27 out of 224 beaches) and only during a 109-day time window (15 May – 31 August). Green turtles set record highs in 2011, 2013, 2015, and 2017. The low nest numbers observed in 2018 were expected and are not cause for concern because green turtles tend to follow a two-year reproductive cycle and, typically, there are wide year-to-year fluctuations in the number of nests recorded.
Below: Annual green turtle nest counts on core index beaches. Since 1989, nest counts have ranged from less than 300 to almost 39,000 in 2017. Numbers show a mostly biennial pattern of fluctuation, with records set on 2011, 2013, 2015 and 2017.
Surveyors counted 316 leatherback nests on the 27 core index beaches in 2018. These counts do not include leatherback nesting at the beginning of the season (before May 15), nor do they represent all the beaches in Florida where leatherbacks nest; however, the index provided by these counts remains a representative reflection of trends. Similar to nest counts for green turtles, leatherback nest counts have been increasing exponentially over the period of monitoring. However, while green turtle nest numbers on Florida’s index beaches continue to rise, leatherback nest numbers have been declining since 2014. More years of standardized nest counts are needed to understand whether the fluctuation is natural or warrant concern.
Below: Annual leatherback nest counts on core Index beaches. From 1989 through 2018, leatherback nests at core index beaches varied from a minimum of 30 nests in 1990 to a maximum of 657 in 2014.