The Florida Index Nesting Beach Survey records sea turtle nest counts on a standardized set of index beaches. Researchers use the annual survey to determine nesting trends.
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 standardized data-collection criteria to measure seasonal nesting and allow accurate comparisons between beaches and between years. Consistent effort by location and date 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 under index-survey criteria.
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 train beach surveyors and compile data from the annual surveys.
At a core set of index beaches monitored since 1989, trained surveyors monitor 320 kilometers of nesting beach (nearly 200 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). Researchers record nests and nesting attempts by species, nest location and date. Index nest counts represent approximately 69 percent of known loggerhead nesting in Florida, 74 percent of known green turtle nesting and 34 percent of known leatherback nesting.
A loggerhead sea turtle throws sand over a nest,
concealing her eggs, on an index beach in Brevard County.
Observed loggerhead nest counts on Florida’s 26 core index beaches vary from a peak of 59,918 in 1998 to a low of 28,074 in 2007. Since 2007, there has been a general increase in nest counts. This increase includes the most recent nesting season (2012), which had 58,172 loggerhead nests counted – the second highest count in 24 years. Index beaches in the Florida Panhandle, which are not part of the set of core beaches, also had high loggerhead nest counts in 2012. Following a general decline in counts since 1997 when surveys of Panhandle index beaches began, the 2012 season had the highest number recorded in 16 years of nest counts.
From 1989 through 2012, annual loggerhead nests at the core index beaches ranged
from 28,074 to 59,918 nests. 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.
Between 1997 and 2011, there was a general decline in the annual number
of loggerhead nests counted on Panhandle Florida index beaches;
2012, however, saw the highest nest count in 16 years.
Concern over declines in annual loggerhead nest counts 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 2012.
Green Turtle Nests
Green turtle nest counts have increased approximately tenfold since counts began in 1989 – a trend that differs dramatically from that of the loggerhead. The nest count for 2012 was lower than that of the previous year, but this difference is consistent with the largely biennial nesting variation that green turtles have shown in the past.
Since 1989, green turtle nests at core index beaches have ranged from 267 to 10,701,
peaking in 2011. Numbers show a mostly biennial pattern of fluctuation.
Surveyors counted 515 leatherback nests on core index beaches in 2012. These counts do not include leatherback nesting at the beginning of the season before May 15; 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.
From 1989 through 2012, leatherback nests at core index beaches numbered from 27 to 615.